EVOLUTION IN MODERN

 THOUGHT

 BY HAECKEL, THOMSON, WEISMANN

 AND OTHERS

 THE MODERN LIBRARY

 PUBLISHERS :: :: NEW YORK

 * * * * *

CONTENTS

I DARWIN'S PREDECESSORS

 J. Arthur Thomson, Professor of Natural History in the University of Aberdeen

II _The Selection Theory_

 August Weismann, Professor of Zoology in the University of Freiburg (Baden)

III HEREDITY AND VARIATION IN MODERN LIGHTS

 W. Bateson, Professor of Biology in the University of Cambridge

IV "THE DESCENT OF MAN"

 G. Schwalbe, Professor of Anatomy in the University of Strassburg

V CHARLES DARWIN AS AN ANTHROPOLOGIST

 Ernst Haeckel, Professor of Zoology in the University of Jena

VI MENTAL FACTORS IN EVOLUTION

 C. Lloyd Morgan, Professor of Psychology at University College, Bristol

VII THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY

 H. Höffding, Professor of Philosophy in the University of Copenhagen

VIII THE INFLUENCE OF DARWIN UPON RELIGIOUS THOUGHT

 Rev. P. H. Waggett

IX DARWINISM AND HISTORY

 J. B. Bury, Regious Professor of Modern History in the University of Cambridge

X DARWINISM AND SOCIOLOGY

 C. Bouglé, Professor of Social Philosophy in the University of Toulouse, and Deputy-Professor at the Sorbonne, Paris

 * * * * *

EVOLUTION IN MODERN THOUGHT

I

DARWIN'S PREDECESSORS

BY J. ARTHUR THOMSON

_Professor of Natural History in the University of Aberdeen_

In seeking to discover Darwin's relation to his predecessors it isuseful to distinguish the various services which he rendered to thetheory of organic evolution. 

(I) As everyone knows, the general idea of the Doctrine of Descent isthat the plants and animals of the present day are the linealdescendants of ancestors on the whole somewhat simpler, that theseagain are descended from yet simpler forms, and so on backwardstowards the literal "Protozoa" and "Protophyta" about which weunfortunately know nothing. Now no one supposes that Darwin originatedthis idea, which in rudiment at least is as old as Aristotle. WhatDarwin did was to make it current intellectual coin. He gave it a formthat commended itself to the scientific and public intelligence of theday, and he won widespread conviction by showing with consummate skillthat it was an effective formula to work with, a key which no lockrefused. In a scholarly, critical, and pre-eminently fair-minded way, admitting difficulties and removing them, foreseeing objections andforestalling them, he showed that the doctrine of descent supplied amodal interpretation of how our present-day fauna and flora have cometo be. 

(II) In the second place, Darwin applied the evolution-idea toparticular problems, such as the descent of man, and showed what apowerful organon it is, introducing order into masses of uncorrelatedfacts, interpreting enigmas both of structure and function, bothbodily and mental, and, best of all, stimulating and guiding furtherinvestigation. But here again it cannot be claimed that Darwin wasoriginal. The problem of the descent or ascent of man, and otherparticular cases of evolution, had attracted not a few naturalistsbefore Darwin's day, though no one [except Herbert Spencer in thepsychological domain (1855)] had come near him in precision andthoroughness of inquiry. 

(III) In the third place, Darwin contributed largely to a knowledge ofthe factors in the evolution-process, especially by his analysis ofwhat occurs in the case of domestic animals and cultivated plants, andby his elaboration of the theory of Natural Selection which AlfredRussel Wallace independently stated at the same time, and of whichthere had been a few previous suggestions of a more or less vaguedescription. It was here that Darwin's originality was greatest, forhe revealed to naturalists the many different forms--often verysubtle--which natural selection takes, and with the insight of adisciplined scientific imagination he realised what a mighty engine ofprogress it has been and is. 

(IV) As an epoch-marking contribution, not only to Ætiology but toNatural History in the widest sense, we rank the picture which Darwingave to the world of the web of life, that is to say, of theinter-relations and linkages in Nature. For the Biology of theindividual--if that be not a contradiction in terms--no idea is morefundamental than that of the correlation of organs, but Darwin's mostcharacteristic contribution was not less fundamental, --it was the ideaof the correlation of organisms. This, again, was not novel; we findit in the works of naturalists like Christian Conrad Sprengel, Gilbert White, and Alexander von Humboldt, but the realisation of itsfull import was distinctly Darwinian. 

_As Regards the General Idea of Organic Evolution_

While it is true, as Prof. H. F. Osborn puts it, that "'Before andafter Darwin' will always be the _ante et post urbem conditam_ ofbiological history, " it is also true that the general idea of organicevolution is very ancient. In his admirable sketch _From the Greeks toDarwin_, [1] Prof. Osborn has shown that several of the ancientphilosophers looked upon Nature as a gradual development and as stillin process of change. In the suggestions of Empedocles, to take thebest instance, there were "four sparks of truth, --first, that thedevelopment of life was a gradual process; second, that plants wereevolved before animals; third, that imperfect forms were graduallyreplaced (not succeeded) by perfect forms; fourth, that the naturalcause of the production of perfect forms was the extinction of theimperfect. "[2] But the fundamental idea of one stage giving origin toanother was absent. As the blue Ægean teemed with treasures of beautyand threw many upon its shores, so did Nature produce like a fertileartist what had to be rejected as well as what was able to survive, but the idea of one species emerging out of another was not yetconceived. 

Aristotle's views of Nature[3] seem to have been more definitelyevolutionist than those of his predecessors, in this sense, at least, that he recognised not only an ascending scale, but a genetic seriesfrom polyp to man and an age-long movement towards perfection. "It isdue to the resistance of matter to form that Nature can only rise bydegrees from lower to higher types. " "Nature produces those thingswhich, being continually moved by a certain principle contained inthemselves, arrive at a certain end. "

To discern the outcrop of evolution-doctrine in the long intervalbetween Aristotle and Bacon seems to be very difficult, and some ofthe instances that have been cited strike one as forced. Epicurus andLucretius, often called poets of evolution, both pictured animals asarising directly out of the earth, very much as Milton's lion longafterwards pawed its way out. Even when we come to Bruno who wrotethat "to the sound of the harp of the Universal Apollo (the WorldSpirit), the lower organisms are called by stages to higher, and thelower stages are connected by intermediate forms with the higher, "there is great room, as Prof. Osborn points out, [4] for difference ofopinion as to how far he was an evolutionist in our sense of the term. 

The awakening of natural science in the sixteenth century brought thepossibility of a concrete evolution theory nearer, and in the earlyseventeenth century we find evidences of a new spirit--in theembryology of Harvey and the classifications of Ray. Besides sobernaturalists there were speculative dreamers in the sixteenth andseventeenth centuries who had at least got beyond static formulae, but, as Professor Osborn points out, [5] "it is a very striking fact, that the basis of our modern methods of studying the Evolution problemwas established not by the early naturalists nor by the speculativewriters, but by the Philosophers. " He refers to Bacon, Descartes, Leibnitz, Hume, Kant, Lessing, Herder, and Schelling. "They alone wereupon the main track of modern thought. It is evident that they weregroping in the dark for a working theory of the Evolution of life, andit is remarkable that they clearly perceived from the outset that thepoint to which observation should be directed was not the past but thepresent mutability of species, and further, that this mutability wassimply the variation of individuals on an extended scale. "

Bacon seems to have been one of the first to think definitely aboutthe mutability of species, and he was far ahead of his age in hissuggestion of what we now call a Station of Experimental Evolution. Leibnitz discusses in so many words how the species of animals may bechanged and how intermediate species may once have linked those thatnow seem discontinuous. "All natural orders of beings present but asingle chain". .. . "All advances by degrees in Nature, and nothing byleaps. " Similar evolutionist statements are to be found in the worksof the other "philosophers, " to whom Prof. Osborn refers, who were, indeed, more scientific than the naturalists of their day. It must beborne in mind that the general idea of organic evolution--that thepresent is the child of the past--is in great part just the idea ofhuman history projected upon the natural world, differentiated by thequalification that the continuous "Becoming" has been wrought out byforces inherent in the organisms themselves and in their environment. 

A reference to Kant[6] should come in historical order after Buffon, with whose writings he was acquainted, but he seems, along with Herderand Schelling, to be best regarded as the culmination of theevolutionist philosophers--of those at least who interested themselvesin scientific problems. In a famous passage he speaks of "theagreement of so many kinds of animals in a certain common plan ofstructure" . .. An "analogy of forms" which "strengthens thesupposition that they have an actual blood-relationship, due toderivation from a common parent. " He speaks of "the great Family ofcreatures, for as a Family we must conceive it, if the above-mentionedcontinuous and connected relationship has a real foundation. " Prof. Osborn alludes to the scientific caution which led Kant, biology beingwhat it was, to refuse to entertain the hope "that a Newton may oneday arise even to make the production of a blade of grasscomprehensible, according to natural laws ordained by no intention. "As Prof. Haeckel finely observes, Darwin rose up as Kant's Newton. [7]

The scientific renaissance brought a wealth of fresh impressions andsome freedom from the tyranny of tradition, and the twofold stimulusstirred the speculative activity of a great variety of men from oldClaude Duret of Moulins, of whose weird transformism (1609) Dr. Henryde Varigny[8] gives us a glimpse, to Lorenz Oken (1779-1851) whosewritings are such mixtures of sense and nonsense that some regard himas a far-seeing prophet and others as a fatuous follower ofintellectual will-o'-the-wisps. Similarly, for De Maillet, Maupertuis, Diderot, Bonnet, and others, we must agree with Professor Osborn thatthey were not actually in the main Evolution movement. Some have beenincluded in the roll of honour on very slender evidence, Robinet forinstance, whose evolutionism seems to us extremely dubious. [9]

The first naturalist to give a broad and concrete expression to theevolutionist doctrine of descent was Buffon (1707-1788), but it isinteresting to recall the fact that his contemporary Linnæus(1707-1778), protagonist of the counter-doctrine of the fixity ofspecies, [10] went the length of admitting (in 1762) that new speciesmight arise by inter-crossing. Buffon's position among the pioneers ofthe evolution-doctrine is weakened by his habit of vacillating betweenhis own conclusions and the orthodoxy of the Sorbonne, but there is nodoubt that he had firm grasp of the general idea of "l'enchaînment desêtres. "

Erasmus Darwin (1731-1802), probably influenced by Buffon, was anotherfirm evolutionist, and the outline of his argument in the_Zoonomia_[11] might serve in part at least to-day. "When we revolvein our minds the metamorphoses of animals, as from the tadpole to thefrog; secondly, the changes produced by artificial cultivation, as inthe breeds of horses, dogs, and sheep; thirdly, the changes producedby conditions of climate and of season, as in the sheep of warmclimates being covered with hair instead of wool, and the hares andpartridges of northern climates becoming white in winter: when, further, we observe the changes of structure produced by habit, asseen especially in men of different occupations; or the changesproduced by artificial mutilation and prenatal influences, as in thecrossing of species and production of monsters; fourth, when weobserve the essential unity of plan in all warm-blooded animals, --weare led to conclude that they have been alike produced from a similarliving filament". .. . "From thus meditating upon the minute portion oftime in which many of the above changes have been produced, would itbe too bold to imagine, in the great length of time since the earthbegan to exist, perhaps millions of years before the commencement ofthe history of mankind, that all warm-blooded animals have arisen fromone living filament?". .. "This idea of the gradual generation of allthings seems to have been as familiar to the ancient philosophers asto the modern ones, and to have given rise to the beautifulhieroglyphic figure of the πρω̃τον ὠὁν, or first great egg, produced by night, that is, whose origin is involved in obscurity, andanimated by Ἔρωσ, that is, by Divine Love; from whenceproceeded all things which exist. "

Lamarck (1744-1829) seems to have become an evolutionistindependently of Erasmus Darwin's influence, though the parallelismbetween them is striking. He probably owed something to Buffon, but hedeveloped his theory along a different line. Whatever view be held inregard to that theory there is no doubt that Lamarck was athorough-going evolutionist. Professor Haeckel speaks of the_Philosophie Zoologique_ as "the first connected and thoroughlylogical exposition of the theory of descent. "[12]

Besides the three old masters, as we may call them, Buffon, ErasmusDarwin, and Lamarck, there were other quite convinced pre-Darwinianevolutionists. The historian of the theory of descent must takeaccount of Treviranus whose _Biology or Philosophy of Animate Nature_is full of evolutionary suggestions; of Etienne Geoffroy St. Hilaire, who in 1830, before the French Academy of Sciences, fought withCuvier, the fellow-worker of his youth, an intellectual duel on thequestion of descent; of Goethe, one of the founders of morphology andthe greatest poet of Evolution--who, in his eighty-first year, heardthe tidings of Geoffrey St. Hilaire's defeat with an interest whichtranscended the political anxieties of the time; and of many otherswho had gained with more or less confidence and clearness a newoutlook on Nature. It will be remembered that Darwin refers tothirty-four more or less evolutionist authors in his HistoricalSketch, and the list might be added to. Especially when we come nearto 1858 do the numbers increase, and one of the most remarkable, asalso most independent champions of the evolution-idea before that datewas Herbert Spencer, who not only marshalled the arguments in a veryforcible way in 1852, but applied the formula in detail in his_Principles of Psychology_ in 1855. [13]

It is right and proper that we should shake ourselves free from allcreationist appreciations of Darwin, and that we should recognise theservices of pre-Darwinian evolutionists who helped to make the timeripe, yet one cannot help feeling that the citation of them is apt tosuggest two fallacies. It may suggest that Darwin simply entered intothe labours of his predecessors, whereas, as a matter of fact, he knewvery little about them till after he had been for years at work. Towrite, as Samuel Butler did, "Buffon planted, Erasmus Darwin andLamarck watered, but it was Mr. Darwin who said 'That fruit is ripe, 'and shook it into his lap" . .. Seems to us a quite misleading versionof the facts of the case. The second fallacy which the historicalcitation is a little apt to suggest is that the filiation of ideas isa simple problem. On the contrary, the history of an idea, like thepedigree of an organism, is often very intricate, and the evolution ofthe evolution-idea is bound up with the whole progress of the world. Thus in order to interpret Darwin's clear formulation of the idea oforganic evolution and his convincing presentation of it, we have to domore than go back to his immediate predecessors, such as Buffon, Erasmus Darwin, and Lamarck; we have to inquire into the acceptance ofevolutionary conceptions in regard to other orders of facts, such asthe earth and the solar system;[14] we have to realise how the growingsuccess of scientific interpretation along other lines gave confidenceto those who refused to admit that there was any domain from whichscience could be excluded as a trespasser; we have to take account ofthe development of philosophical thought, and even of theological andreligious movements; we should also, if we are wise enough, considersocial changes. In short, we must abandon the idea that we canunderstand the history of any science as such, without reference tocontemporary evolution in other departments of activity. 

While there were many evolutionists before Darwin, few of them wereexpert naturalists and few were known outside a small circle; what wasof much more importance was that the genetic view of Nature wasinsinuating itself in regard to other than biological orders of facts, here a little and there a little, and that the scientific spirit hadripened since the days when Cuvier laughed Lamarck out of court. Howwas it that Darwin succeeded where others had failed? Because, in thefirst place, he had clear visions--"pensées de la jeunesse, executéespar l'âge mûr"--which a University curriculum had not made impossible, which the _Beagle voyage_ made vivid, which an unrivalled Britishdoggedness made real--visions of the web of life, of the fountain ofchange within the organism, of the struggle for existence and itswinnowing, and of the spreading genealogical tree. Because, in thesecond place, he put so much grit into the verification of hisvisions, putting them to the proof in an argument which is of itskind--direct demonstration being out of the question--quiteunequalled. Because, in the third place, he broke down the oppositionwhich the most scientific had felt to the seductive modal formula ofevolution by bringing forward a more plausible theory of the processthan had been previously suggested. Nor can one forget, sincequestions of this magnitude are human and not merely academic, that hewrote so that all men could understand. 

_As Regards the Factors of Evolution_

It is admitted by all who are acquainted with the history of biologythat the general idea of organic evolution as expressed in theDoctrine of Descent was quite familiar to Darwin's grandfather and toothers before and after him, as we have briefly indicated. It mustalso be admitted that some of these pioneers of evolutionism did morethan apply the evolution-idea as a modal formula of becoming, theybegan to inquire into the factors in the process. Thus there werepre-Darwinian theories of evolution, and to these we must now brieflyrefer. [15]

In all biological thinking we have to work with the categoriesOrganism--Function--Environment, and theories of evolution may beclassified in relation to these. To some it has always seemed that thefundamental fact is the living organism, --a creative agent, a strivingwill, a changeful Proteus, selecting its environment, adjusting itselfto it, self-differentiating and self-adaptive. The necessity ofrecognising the importance of the organism is admitted by allDarwinians who start with inborn variations, but it is open toquestion whether the whole truth of what we might call the Goethianposition is exhausted in the postulate of inherent variability. 

To others it has always seemed that the emphasis should be laid onFunction, --on use and disuse, on doing and not doing. Practice makesperfect; _c'est à force de forger qu'on devient forgeron_. This is oneof the fundamental ideas of Lamarckism; to some extent it met withDarwin's approval; and it finds many supporters to-day. One of theablest of these--Mr. Francis Darwin--has recently given strong reasonsfor combining a modernised Lamarckism with what we usually regard assound Darwinism. [16]

To others it has always seemed that the emphasis should be laid on theEnvironment, which wakes the organism to action, prompts it to change, makes dints upon it, moulds it, prunes it, and finally, perhaps, kills it. It is again impossible to doubt that there is truth in this view, for evenif environmentally induced "modifications" be not transmissible, environmentally induced "variations" are; and even if the direct influenceof the environment be less important than many enthusiastic supporters ofthis view--may we call them Buffonians--think, there remains the indirectinfluence which Darwinians in part rely on, --the eliminative process. Evenif the extreme view be held that the only form of discriminate eliminationthat counts is inter-organismal competition, this might be included underthe rubric of the animate environment. 

In many passages Buffon[17] definitely suggested that environmentalinfluences--especially of climate and food--were directly productiveof changes in organisms, but he did not discuss the question of thetransmissibility of the modifications so induced, and it is difficultto gather from his inconsistent writings what extent of transformationhe really believed in. Prof. Osborn says of Buffon: "The struggle forexistence, the elimination of the least-perfected species, the contestbetween the fecundity of certain species and their constantdestruction, are all clearly expressed in various passages. " He quotestwo of these:[18]

"Le cours ordinaire de la nature vivante, est en général toujoursconstant, toujours le même; son mouvement, toujours régulier, roulesur deux points inébranlables: l'un, la fécondité sans bornes donnée àtoutes les espèces; l'autre, les obstacles sans nombre qui réduisentcette fécondité à une mesure déterminée et ne laissent en tout tempsqu'à peu près la même quantité d'individus de chaque espèce" . .. "Lesespèces les moins parfaites, les plus délicates, les plus pesantes, les moins agissantes, les moins armées, etc. , ont déjà disparu oudisparaîtront. ". 

Erasmus Darwin[19] had a firm grip of the "idea of the gradualformation and improvement of the Animal world, " and he had his theoryof the process. No sentence is more characteristic than this: "Allanimals undergo transformations which are in part produced by theirown exertions, in response to pleasures and pains, and many of theseacquired forms or propensities are transmitted to their posterity. "This is Lamarckism before Lamarck, as his grandson pointed out. Hiscentral idea is that wants stimulate efforts and that these result inimprovements which subsequent generations make better still. Herealised something of the struggle for existence and even pointed outthat this advantageously checks the rapid multiplication. "As Dr. Krause points out, Darwin just misses the connection between thisstruggle and the Survival of the Fittest. "[20]

Lamarck[21] (1744-1829) seems to have thought out his theory ofevolution without any knowledge of Erasmus Darwin's which it closelyresembled. The central idea of his theory was the cumulativeinheritance of functional modifications. "Changes in environment bringabout changes in the habits of animals. Changes in their wantsnecessarily bring about parallel changes in their habits. If new wantsbecome constant or very lasting, they form new habits, the new habitsinvolve the use of new parts, or a different use of old parts, whichresults finally in the production of new organs and the modificationof old ones. " He differed from Buffon in not attaching importance, asfar as animals are concerned, to the direct influence of theenvironment, "for environment can effect no direct change whateverupon the organisation of animals, " but in regard to plants he agreedwith Buffon that external conditions directly moulded them. 

Treviranus[22] (1776-1837), whom Huxley ranked beside Lamarck, was onthe whole Buffonian, attaching chief importance to the influence of achangeful environment both in modifying and in eliminating, but he wasalso Goethian, for instance in his idea that species like individualspass through periods of growth, full bloom, and decline. "Thus, it isnot only the great catastrophes of Nature which have causedextinction, but the completion of cycles of existence, out of whichnew cycles have begun. " A characteristic sentence is quoted by Prof. Osborn: "In every living being there exists a capability of an endlessvariety of form-assumption; each possesses the power to adapt itsorganisation to the changes of the outer world, and it is this power, put into action by the change of the universe, that has raised thesimple zoophytes of the primitive world to continually higher stagesof organisation, and has introduced a countless variety of speciesinto animate Nature. "

Goethe[23] (1749-1832), who knew Buffon's work but not Lamarck's, ispeculiarly interesting as one of the first to use the evolution-ideaas a guiding hypothesis, e. G. In the interpretation of vestigialstructures in man, and to realise that organisms express an attempt tomake a compromise between specific inertia and individual change. Hegave the finest expression that science has yet known--if it has knownit--of the kernel-idea of what is called "bathmism, " the idea of an"inherent growth-force"--and at the same time he held that "the way oflife powerfully reacts upon all form" and that the orderly growth ofform "yields to change from externally acting causes. "

Besides Buffon, Erasmus Darwin, Lamarck, Treviranus, and Goethe, there were other "pioneers of evolution, " whose views have been oftendiscussed and appraised. Étienne Geoffroy Saint-Hilaire (1772-1884), whose work Goethe so much admired, was on the whole Buffonian, emphasising the direct action of the changeful _milieu_. "Species varywith their environment, and existing species have descended bymodification from earlier and somewhat simpler species. " He had aglimpse of the selection idea, and believed in mutations or suddenleaps--induced in the embryonic condition by external influences. Thecomplete history of evolution-theories will include many instances ofguesses at truth which were afterwards substantiated, thus thegeographer von Buch (1773-1853) detected the importance of theIsolation factor on which Wagner, Romanes, Gulick and others have laidgreat stress, but we must content ourselves with recalling one otherpioneer, the author of the _Vestiges of Creation_ (1844), a work whichpassed through ten editions in nine years and certainly helped toharrow the soil for Darwin's sowing. As Darwin said, "it did excellentservice in this country in calling attention to the subject, inremoving prejudice, and in thus preparing the ground for the receptionof analogous views. "[24] Its author, Robert Chambers (1802-1871) wasin part a Buffonian--maintaining that environment moulded organismsadaptively, and in part a Goethian--believing in an inherentprogressive impulse which lifted organisms from one grade oforganisation to another. 

_As Regards Natural Selection_

The only thinker to whom Darwin was directly indebted, so far as thetheory of Natural Selection is concerned, was Malthus, and we may oncemore quote the well-known passage in the Autobiography: "In October, 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement 'Malthus on Population, ' and beingwell prepared to appreciate the struggle for existence whicheverywhere goes on from long-continued observation of the habits ofanimals and plants, it at once struck me that under thesecircumstances favourable variations would tend to be preserved, andunfavourable ones to be destroyed. The result of this would be theformation of new species. "[25]

Although Malthus gives no adumbration of the idea of Natural Selectionin his exposition of the eliminative processes which go on in mankind, the suggestive value of his essay is undeniable, as is strikinglyborne out by the fact that it gave to Alfred Russel Wallace also "thelong-sought clue to the effective agent in the evolution of organicspecies. "[26] One day in Ternate when he was resting between fits offever, something brought to his recollection the work of Malthus whichhe had read twelve years before. "I thought of his clear exposition of'the positive checks to increase'--disease, accidents, war, andfamine--which keep down the population of savage races to so muchlower an average than that of more civilized peoples. It then occurredto me that these causes or their equivalents are continually acting inthe case of animals also; and as animals usually breed much morerapidly than does mankind, the destruction every year from thesecauses must be enormous in order to keep down the numbers of eachspecies, since they evidently do not increase regularly from year toyear, as otherwise the world would long ago have been densely crowdedwith those that breed most quickly. Vaguely thinking over the enormousand constant destruction which this implied, it occurred to me to askthe question, Why do some die and some live? And the answer wasclearly, that on the whole the best fitted live. From the effects ofdisease the most healthy escaped; from enemies the strongest, theswiftest, or the most cunning; from famine the best hunters or thosewith the best digestion; and so on. Then it suddenly flashed upon methat this self-acting process would necessarily _improve the race_, because in every generation the inferior would inevitably be killedoff and the superior would remain--that is, _the fittest wouldsurvive_. "[27] We need not apologise for this long quotation, it is atribute to Darwin's magnanimous colleague, the Nestor of theevolutionist camp, --and it probably indicates the line of thoughtwhich Darwin himself followed. It is interesting also to recall thefact that in 1852, when Herbert Spencer wrote his famous _Leader_article on "The Development Hypothesis" in which he argued powerfullyfor the thesis that the whole animate world is the result of anage-long process of natural transformation, he wrote for _TheWestminster Review_ another important essay, "A Theory of Populationdeduced from the General Law of Animal Fertility, " towards the closeof which he came within an ace of recognising that the struggle forexistence was a factor in organic evolution. At a time when pressureof population was practically interesting men's minds, Darwin, Wallace, and Spencer were being independently led from a socialproblem to a biological theory. There could be no better illustration, as Prof. Patrick Geddes has pointed out, of the Comtian thesis thatscience is a "social phenomenon. "

Therefore, as far more important than any further ferreting out ofvague hints of Natural Selection in books which Darwin never read, wewould indicate by a quotation the view that the central idea inDarwinism is correlated with contemporary social evolution. "Thesubstitution of Darwin for Paley as the chief interpreter of the orderof nature is currently regarded as the displacement of ananthropomorphic view by a purely scientific one: a little reflection, however, will show that what has actually happened has been merely thereplacement of the anthropomorphism of the eighteenth century by thatof the nineteenth. For the place vacated by Paley's theological andmetaphysical explanation has simply been occupied by that suggested toDarwin and Wallace by Malthus in terms of the prevalent severity ofindustrial competition, and those phenomena of the struggle forexistence which the light of contemporary economic theory has enabledus to discern, have thus come to be temporarily exalted into acomplete explanation of organic progress. "[28] It goes without sayingthat the idea suggested by Malthus was developed by Darwin into abiological theory which was then painstakingly verified by being usedas an interpretative formula, and that the validity of a theory soestablished is not affected by what suggested it, but the practicalquestion which this line of thought raises in the mind is this: ifBiology did thus borrow with such splendid results from social theory, why should we not more deliberately repeat the experiment?

Darwin was characteristically frank and generous in admitting that theprinciple of Natural Selection had been independently recognised byDr. W. C. Wells in 1813 and by Mr. Patrick Matthew in 1831, but he hadno knowledge of these anticipations when he published the firstedition of _The Origin of Species_. Wells, whose "Essay on Dew" isstill remembered, read in 1813 before the Royal Society a short paperentitled "An Account of a White Female, part of whose skin resemblesthat of a Negro" (published in 1818). In this communication, as Darwinsaid, "he observes, firstly, that all animals tend to vary in somedegree, and, secondly, that agriculturists improve their domesticatedanimals by selection; and then, he adds, but what is done in thislatter case 'by art, seems to be done with equal efficacy, though moreslowly, by nature, in the formation of varieties of mankind, fittedfor the country which they inhabit. '"[29] Thus Wells had the clearidea of survival dependent upon a favourable variation, but he makesno more use of the idea and applies it only to man. There is not inthe paper the least hint that the author ever thought of generalisingthe remarkable sentence quoted above. 

Of Mr. Patrick Matthew, who buried his treasure in an appendix to awork on _Naval Timber and Arboriculture_, Darwin said that "he clearlysaw the full force of the principle of natural selection. " In 1860Darwin wrote--very characteristically--about this to Lyell: "Mr. Patrick Matthew publishes a long extract from his work on _NavalTimber and Arboriculture_, published in 1831, in which he briefly butcompletely anticipates the theory of Natural Selection. I have orderedthe book, as some passages are rather obscure, but it is certainly, Ithink, a complete but not developed anticipation. Erasmus always saidthat surely this would be shown to be the case some day. Anyhow, onemay be excused in not having discovered the fact in a work on NavalTimber. "[30]

De Quatrefages and De Varigny have maintained that the botanist Naudinstated the theory of evolution by natural selection in 1852. Heexplains very clearly the process of artificial selection, and saysthat in the garden we are following Nature's method. "We do not thinkthat Nature has made her species in a different fashion from that inwhich we proceed ourselves in order to make our variations. " But, asDarwin said, "he does not show how selection acts under nature. "Similarly it must be noted in regard to several pre-Darwinian picturesof the struggle for existence (such as Herder's, who wrote in 1790"All is in struggle . .. Each one for himself" and so on), that arecognition of this is only the first step in Darwinism. 

Profs. E. Perrier and H. F. Osborn have called attention to aremarkable anticipation of the selection-idea which is to be found inthe speculations of Étienne Geoffroy Saint-Hilaire (1825-1828) on theevolution of modern Crocodilians from the ancient Teleosaurs. Changingenvironment induced changes in the respiratory system and far-reachingconsequences followed. The atmosphere, acting upon the pulmonarycells, brings about "modifications which are favourable or destructive('funestes'); these are inherited, and they influence all the rest ofthe organisation of the animal because if these modifications lead toinjurious effects the animals which exhibit them perish and arereplaced by others of a somewhat different form, a form changed so asto be adapted to (à la convenance) the new environment. "

Prof. E. B. Poulton[31] has shown that the anthropologist James CowlesPrichard (1786-1848) must be included even in spite of himself amongthe precursors of Darwin. In some passages of the second edition ofhis _Researches into the Physical History of Mankind_ (1826), hecertainly talks evolution and anticipates Prof. Weismann in denyingthe transmission of acquired characters. He is, however, sadlyself-contradictory and his evolutionism weakens in subsequenteditions--the only ones that Darwin saw. Prof. Poulton finds inPrichard's work a recognition of the operation of Natural Selection. "After inquiring how it is that 'these varieties are developed andpreserved in connexion with particular climates and differences oflocal situation, ' he gives the following very significant answer: 'Onecause which tends to maintain this relation is obvious. Individualsand families, and even whole colonies perish and disappear in climatesfor which they are, by peculiarity of constitution, not adapted. Ofthis fact proofs have been already mentioned. '" Mr. Francis Darwin andProf. A. C. Seward discuss Prichard's "anticipations" in _More Lettersof Charles Darwin_, Vol. _I. _ p. 43, and come to the conclusion thatthe evolutionary passages are entirely neutralised by others of anopposite trend. There is the same difficulty with Buffon. 

Hints of the idea of Natural Selection have been detected elsewhere. James Watt, [32] for instance, has been reported as one of theanticipators (1851). But we need not prolong the inquiry further, since Darwin did not know of any anticipations until after he hadpublished the immortal work of 1859, and since none of those who gothold of the idea made any use of it. What Darwin did was to follow theclue which Malthus gave him, to realise, first by genius andafterwards by patience, how the complex and subtle struggle forexistence works out a natural selection of those organisms which varyin the direction of fitter adaptation to the conditions of their life. So much success attended his application of the Selection-formula thatfor a time he regarded Natural Selection as almost the sole factor inevolution, variations being pre-supposed; gradually, however, he cameto recognise that there was some validity in the factors which hadbeen emphasised by Lamarck and by Buffon, and in his well knownsumming up in the sixth edition of the _Origin_ he says of thetransformation of species: "This has been effected chiefly through thenatural selection of numerous successive, slight, favourablevariations; aided in an important manner by the inherited effects ofthe use and disuse of parts; and in an unimportant manner, that is, inrelation to adaptive structures, whether past or present, by thedirect action of external conditions, and by variations which seem tous in our ignorance to arise spontaneously. "

To sum up: the idea of organic evolution, older than Aristotle, slowlydeveloped from the stage of suggestion to the stage of verification, and the first convincing verification was Darwin's; from being an _apriori_ anticipation it has become an interpretation of nature, andDarwin is still the chief interpreter; from being a modalinterpretation it has advanced to the rank of a causal theory, themost convincing part of which men will never cease to call Darwinism. 

FOOTNOTES:

[Footnote 1: _Columbia University Biological Series_, Vol. I. New Yorkand London, 1894. We must acknowledge our great indebtedness to thisfine piece of work. ]

[Footnote 2: _op. Cit. _ p. 41. ]

[Footnote 3: See G. J. Romanes, "Aristotle as a Naturalist, "_Contemporary Review_, Vol. Lix. P. 275, 1891; G. Pouchet, _LaBiologie Aristotélique_, Paris, 1885; E. Zeller, _A History of GreekPhilosophy_, London, 1881, and "Ueber die griechischen VorgängerDarwin's, " _Abhandl. Berlin Akad. _ 1878, pp. 111-124. ]

[Footnote 4: _op. Cit. _ p. 81. ]

[Footnote 5: _op. Cit. _ p. 87. ]

[Footnote 6: See Brock, "Die Stellung Kant's zur Deszendenztheorie, "_Biol. Centralbl. _ viii. 1889, pp. 641-648. Fritz Schultze, _Kant undDarwin_, Jena, 1875. ]

[Footnote 7: Mr. Alfred Russel Wallace writes: "We claim for Darwinthat he is the Newton of natural history, and that, just so surely asthat the discovery and demonstration by Newton of the law ofgravitation established order in place of chaos and laid a surefoundation for all future study of the starry heavens, so surely hasDarwin, by his discovery of the law of natural selection and hisdemonstration of the great principle of the preservation of usefulvariations in the struggle for life, not only thrown a flood of lighton the process of development of the whole organic world, but alsoestablished a firm foundation for all future study of nature"(_Darwinism_, London, 1889, p. 9). See also Prof. Karl Pearson's_Grammar of Science_ (2nd edit. ), London, 1900, p. 32. See Osborn, _op. Cit. _ p. 100. ]

[Footnote 8: _Experimental Evolution_. London, 1892. Chap. I. P. 14. ]

[Footnote 9: See J. Arthur Thomson, _The Science of Life_. London, 1899, Chap. XVI. "Evolution of Evolution Theory. "]

[Footnote 10: See Carus Sterne (Ernst Krause), _Die allgemeineWeltanschauung in ihrer historischen Entwickelung_. Stuttgart, 1889. Chapter entitled "Beständigkeit oder Veränderlichkeit derNaturwesen. "]

[Footnote 11: _Zoonomia, or the Laws of Organic Life_, 2 vols. London, 1794; Osborn, _op. Cit. _ p. 145. ]

[Footnote 12: See Alpheus S. Packard, _Lamarck, the Founder ofEvolution, His Life and Work, with Translations of his writings onOrganic Evolution_. London, 1901. ]

[Footnote 13: See Edward Clodd, _Pioneers of Evolution_, London, p. 161, 1897. ]

[Footnote 14: See Chapter ix. "The Genetic View of Nature" in J. T. Merz's _History of European Thought in the Nineteenth Century_, Vol. 2, Edinburgh and London, 1903. ]

[Footnote 15: See Prof. W. A. Locy's _Biology and its Makers_. NewYork, 1908. Part II. "The Doctrine of Organic Evolution. "]

[Footnote 16: Presidential Address to the British Association meetingat Dublin in 1908. ]

[Footnote 17: See in particular Samuel Butler, _Evolution Old andNew_, London, 1879; J. L. De Lanessan, "Buffon et Darwin, " _RevueScientifique_, XLIII. Pp. 385-391, 425-432, 1889. ]

[Footnote 18: _op. Cit. _ p. 136. ]

[Footnote 19: See Ernest Krause and Charles Darwin, _Erasmus Darwin_, London, 1879. ]

[Footnote 20: Osborn, _op. Cit. _ p. 142. ]

[Footnote 21: See E. Perrier, _La Philosophie Zoologique avantDarwin_, Paris, 1884; A. De Quatrefages, _Darwin et ses PrécurseursFrançais_, Paris, 1870; Packard, _op. Cit. _; also Claus, _Lamarck alsBegründer der Descendenzlehre_, Wien, 1888; Haeckel, _Natural Historyof Creation_, Eng. Transl. London, 1879; Lang, _Zur Charakteristik derForschungswege von Lamarck und Darwin_, Jena, 1889. ]

[Footnote 22: See Huxley's article "Evolution in Biology, "_Encyclopaedia Britannica_ (9th edit. ), 1879, pp. 744-751, and Sully'sarticle, "Evolution in Philosophy, " _ibid. _ pp. 751-772. ]

[Footnote 23: See Haeckel, _Die Naturanschauung von Darwin, Goethe undLamarck_, Jena, 1882. ]

[Footnote 24: _Origin of Species_ (6th edit. ), p. Xvii. ]

[Footnote 25: _The Life and Letters of Charles Darwin_, Vol. 1. P. 83. London, 1887. ]

[Footnote 26: A. R. Wallace, _My Life, a Record of Events andOpinions_, London, 1905, Vol. 1, p. 232. ]

[Footnote 27: _My Life_, Vol. 1. P. 361. ]

[Footnote 28: P. Geddes. Article "Biology. " _Chambers'sEncyclopaedia. _]

[Footnote 29: _Origin of Species_ (6th edit. ), p. Xv. ]

[Footnote 30: _Life and Letters_, II, p. 301. ]

[Footnote 31: _Science Progress_, New Series, Vol. 1. 1897. "ARemarkable Anticipation of Modern Views on Evolution. " See also Chap. VI. In _Essays on Evolution_, Oxford, 1908. ]

[Footnote 32: See Prof. Patrick Geddes's article "Variation andSelection, " _Encyclopaedia Britannica_ (9th edit. ) 1888. ]

II

THE SELECTION THEORY

BY AUGUST WEISMANN

_Professor of Zoology in the University of Freiburg_ (_Baden_)

I. THE IDEA OF SELECTION

Many and diverse were the discoveries made by Charles Darwin in thecourse of a long and strenuous life, but none of them has had sofar-reaching an influence on the science and thought of his time asthe theory of selection. I do not believe that the theory of evolutionwould have made its way so easily and so quickly after Darwin took upthe cudgels in favour of it if he had not been able to support it by aprinciple which was capable of solving, in a simple manner, thegreatest riddle that living nature presents to us, --I mean thepurposiveness of every living form relative to the conditions of itslife and its marvellously exact adaptation to these. 

Everyone knows that Darwin was not alone in discovering the principleof selection, and that the same idea occurred simultaneously andindependently to Alfred Russel Wallace. At the memorable meeting ofthe Linnean Society on 1st July, 1858, two papers were read(communicated by Lyell and Hooker) both setting forth the same idea ofselection. One was written by Charles Darwin in Kent, the other byAlfred Wallace in Ternate, in the Malay Archipelago. It was a splendidproof of the magnanimity of these two investigators, that they thus inall friendliness and without envy, united in laying their ideasbefore a scientific tribunal: their names will always shine side byside as two of the brightest stars in the scientific sky. 

The idea of selection set forth by the two naturalists was at the timeabsolutely new, but it was also so simple that Huxley could say of itlater, "How extremely stupid not to have thought of that. " As Darwinwas led to the general doctrine of descent, not through the labours ofhis predecessors in the early years of the century, but by his ownobservations, so it was in regard to the principle of selection. Hewas struck by the innumerable cases of adaptation, as, for instance, that of the woodpeckers and tree-frogs to climbing, or the hooks andfeather-like appendages of seeds, which aid in the distribution ofplants, and he said to himself that an explanation of adaptations wasthe first thing to be sought for in attempting to formulate a theoryof evolution. 

But since adaptations point to _changes_ which have been undergone bythe ancestral forms of existing species, it is necessary, first ofall, to inquire how far species in general are _variable_. ThusDarwin's attention was directed in the first place to the phenomenonof variability, and the use man has made of this, from very earlytimes, in the breeding of his domesticated animals and cultivatedplants. He inquired carefully how breeders set to work, when theywished to modify the structure and appearance of a species to theirown ends, and it was soon clear to him that _selection for breedingpurposes_ played the chief part. 

But how was it possible that such processes should occur in freenature? Who is here the breeder, making the selection, choosing outone individual to bring forth offspring and rejecting others? That wasthe problem that for a long time remained a riddle to him. 

Darwin himself relates how illumination suddenly came to him. He hadbeen reading, for his own pleasure, Malthus' book on Population, and, as he had long known from numerous observations, that every speciesgives rise to many more descendants than ever attain to maturity, andthat, therefore, the greater number of the descendants of a speciesperish without reproducing, the idea came to him that the decision asto which member of a species was to perish and which was to attain tomaturity and reproduction might not be a matter of chance, but mightbe determined by the constitution of the individuals themselves, according as they were more or less fitted for survival. With thisidea the foundation of the theory of selection was laid. 

In _artificial selection_ the breeder chooses out for pairing onlysuch individuals as possess the character desired by him in a somewhathigher degree than the rest of the race. Some of the descendantsinherit this character, often in a still higher degree, and if thismethod be pursued throughout several generations, the race istransformed in respect of that particular character. 

_Natural selection_ depends on the same three factors as _artificialselection_: on _variability_, _inheritance_, and _selection forbreeding_, but this last is here carried out not by a breeder but bywhat Darwin called the "struggle for existence. " This last factor isone of the special features of the Darwinian conception of nature. That there are carnivorous animals which take heavy toll in everygeneration of the progeny of the animals on which they prey, and thatthere are herbivores which decimate the plants in every generation hadlong been known, but it is only since Darwin's time that sufficientattention has been paid to the facts that, in addition to this regulardestruction, there exists between the members of a species a keencompetition for space and food, which limits multiplication, and thatnumerous individuals of each species perish because of unfavourableclimatic conditions. The "struggle for existence, " which Darwinregarded as taking the place of the human breeder in free nature, isnot a direct struggle between carnivores and their prey, but is theassumed competition for survival between individuals _of the same_species, of which, on an average, only those survive to reproducewhich have the greatest power of resistance, while the others, lessfavourably constituted, perish early. This struggle is so keen, that, within a limited area, where the conditions of life have long remainedunchanged, of every species, whatever be the degree of fertility, onlytwo, _on an average_, of the descendants of each pair survive; theothers succumb either to enemies, or to disadvantages of climate, orto accident. A high degree of fertility is thus not an indication ofthe special success of a species, but of the numerous dangers thathave attended its evolution. Of the six young brought forth by a pairof elephants in the course of their lives only two survive in a givenarea; similarly, of the millions of eggs which two thread-worms leavebehind them only two survive. It is thus possible to estimate thedangers which threaten a species by its ratio of elimination, or, since this cannot be done directly, by its fertility. 

Although a great number of the descendants of each generation fallvictims to accident, among those that remain it is still the greateror less fitness of the organism that determines the "selection forbreeding purposes, " and it would be incomprehensible if, in thiscompetition, it were not ultimately, that is, on an average, the bestequipped which survive, in the sense of living long enough toreproduce. 

Thus the principle of natural selection is _the selection of the bestfor reproduction_, whether the "best" refers to the wholeconstitution, to one or more parts of the organism, or to one or morestages of development. Every organ, every part, every character of ananimal, fertility and intelligence included, must be improved in thismanner, and be gradually brought up in the course of generations toits highest attainable state of perfection. And not only mayimprovement of parts be brought about in this way, but new parts andorgans may arise, since, through the slow and minute steps ofindividual or "fluctuating" variations, a part may be added here ordropped out there, and thus something new is produced. 

The principle of selection solved the riddle as to how what waspurposive could conceivably be brought about without the interventionof a directing power, the riddle which animate nature presents to ourintelligence at every turn, and in face of which the mind of a Kantcould find no way out, for he regarded a solution of it as not to behoped for. For, even if we were to assume an evolutionary force thatis continually transforming the most primitive and the simplest formsof life into ever higher forms, and the homogeneity of primitive timesinto the infinite variety of the present, we should still be unable toinfer from this alone how each of the numberless forms adapted toparticular conditions of life should have appeared _precisely at theright moment in the history of the earth_ to which their adaptationswere appropriate, and precisely at the proper place in which all theconditions of life to which they were adapted occurred: thehumming-birds at the same time as the flowers; the trichina at thesame time as the pig; the bark-coloured moth at the same time as theoak, and the wasp-like moth at the same time as the wasp whichprotects it. Without processes of selection we should be obliged toassume a "pre-established harmony" after the famous Leibnitzian model, by means of which the clock of the evolution of organisms is soregulated as to strike in exact synchronism with that of the historyof the earth! All forms of life are strictly adapted to the conditionsof their life, and can persist under these conditions alone. 

There must therefore be an intrinsic connection between the conditionsand the structural adaptations of the organism, and, _since theconditions of life cannot be determined by the animal itself, theadaptations must be called forth by the conditions_. 

The selection theory teaches us how this is conceivable, since itenables us to understand that there is a continual production of whatis non-purposive as well as of what is purposive, but the purposivealone survives, while the non-purposive perishes in the very act ofarising. This is the old wisdom taught long ago by Empedocles. 

II. THE LAMARCKIAN PRINCIPLE

Lamarck, as is well known, formulated a definite theory of evolutionat the beginning of the nineteenth century, exactly fifty years beforethe Darwin-Wallace principle of selection was given to the world. Thisbrilliant investigator also endeavoured to support his theory bydemonstrating forces which might have brought about thetransformations of the organic world in the course of the ages. Inaddition to other factors, he laid special emphasis on the increasedor diminished use of the parts of the body, assuming that thestrengthening or weakening which takes place from this cause duringthe individual life, could be handed on to the offspring, and thusintensified and raised to the rank of a specific character. Darwinalso regarded this _Lamarckian principle_, as it is now generallycalled, as a factor in evolution, but he was not fully convinced ofthe transmissibility of acquired characters. 

As I have here to deal only with the theory of selection, I need notdiscuss the Lamarckian hypothesis, but I must express my opinion thatthere is room for much doubt as to the coöperation of this principlein evolution. Not only is it difficult to imagine how the transmissionof functional modifications could take place, but, up to the presenttime, notwithstanding the endeavours of many excellent investigators, not a single actual proof of such inheritance has been broughtforward. Semon's experiments on plants are, according to the botanistPfeffer, not to be relied on, and even the recent, beautifulexperiments made by Dr. Kammerer on salamanders, cannot, as I hope toshow elsewhere, be regarded as proof, if only because they do not dealat all with functional modifications, that is, with modificationsbrought about by use, and it is to these _alone_ that the Lamarckianprinciple refers. 

III. OBJECTIONS TO THE THEORY OF SELECTION

(_a_) _Saltatory evolution_

The Darwinian doctrine of evolution depends essentially on _thecumulative augmentation_ of minute variations in the direction ofutility. But can such minute variations, which are undoubtedlycontinually appearing among the individuals of the same species, possess any selection-value; can they determine which individuals areto survive, and which are to succumb; can they be increased by naturalselection till they attain to the highest development of a purposivevariation?

To many this seems so improbable that they have urged a theory ofevolution by leaps from species to species. Kölliker, in 1872, compared the evolution of species with the processes which we canobserve in the individual life in cases of alternation of generations. But a polyp only gives rise to a medusa because it has itself arisenfrom one, and there can be no question of a medusa ever having arisensuddenly and _de novo_ from a polyp-bud, if only because both formsare adapted in their structure as a whole, and in every detail to theconditions of their life. A sudden origin, in a natural way, ofnumerous adaptations is inconceivable. Even the degeneration of amedusoid from a free-swimming animal to a mere brood-sac (gonophore)is not sudden and saltatory, but occurs by imperceptible modificationsthroughout hundreds of years, as we can learn from the numerous stagesof the process of degeneration persisting at the same time indifferent species. 

If, then, the degeneration to a simple brood-sac takes place only byvery slow transitions, each stage of which may last for centuries, howcould the much more complex _ascending_ evolution possibly have takenplace by sudden leaps? I regard this argument as capable of furtherextension, for wherever in nature we come upon degeneration, it istaking place by minute steps and with a slowness that makes it notdirectly perceptible, and I believe that this in itself justifies usin concluding that _the same must be true of ascending_ evolution. Butin the latter case the goal can seldom be distinctly recognised whilein cases of degeneration the starting-point of the process can oftenbe inferred, because several nearly related species may representdifferent stages. 

In recent years Bateson in particular has championed the idea ofsaltatory, or so-called discontinuous evolution, and has collected anumber of cases in which more or less marked variations have suddenlyappeared. These are taken for the most part from among domesticatedanimals which have been bred and crossed for a long time, and it ishardly to be wondered at that their much mixed and much influencedgerm-plasm should, under certain conditions, give rise to remarkablephenomena, often indeed producing forms which are strongly suggestiveof monstrosities, and which would undoubtedly not survive in freenature, unprotected by man. I should regard such cases as due to anintensified germinal selection--though this is to anticipate alittle--and from this point of view it cannot be denied that they havea special interest. But they seem to me to have no significance as faras the transformation of species is concerned, if only because of theextreme rarity of their occurrence. 

There are, however, many variations which have appeared in a suddenand saltatory manner, and some of these Darwin pointed out anddiscussed in detail: the copper beech, the weeping trees, the oak with"fern-like leaves, " certain garden-flowers, etc. But none of them havepersisted in free nature, or evolved into permanent types. 

On the other hand, wherever enduring types have arisen, we find tracesof a gradual origin by successive stages, even if, at first sight, their origin may appear to have been sudden. This is the case with_seasonal Dimorphism_, the first known cases of which exhibited markeddifferences between the two generations, the winter and the summerbrood. Take for instance the much discussed and studied form_Vanessa_ (_Araschnia_) _levana-prorsa_. Here the differences betweenthe two forms are so great and so apparently disconnected, that onemight almost believe it to be a sudden mutation, were it not that oldtransition-stages can be called forth by particular temperatures, andwe know other butterflies, as for instance our Garden Whites, in whichthe differences between the two generations are not nearly so marked;indeed, they are so little apparent that they are scarcely likely tobe noticed except by experts. Thus here again there are small initialsteps, some of which, indeed, must be regarded as adaptations, such asthe green-sprinkled or lightly tinted under-surface which gives them adeceptive resemblance to parsley or to Cardamine leaves. 

Even if saltatory variations do occur, we cannot assume that these_have ever led to forms which are capable of survival under theconditions of wild life_. Experience has shown that in plants whichhave suddenly varied the power of persistence is diminished. Korschinsky attributes to them weaknesses of organisation in general;"they bloom late, ripen few of their seeds, and show greatsensitiveness to cold. " These are not the characters which make forsuccess in the struggle for existence. 

We must briefly refer here to the views--much discussed in the lastdecade--of H. De Vries, who believes that the roots of transformationmust be sought for in _saltatory variations arising from internalcauses_, and distinguishes such _mutations_, as he has called them, from ordinary individual variations, in that they breed true, that is, with strict in-breeding they are handed on pure to the nextgeneration. I have elsewhere endeavoured to point out the weaknessesof this theory, [33] and I am the less inclined to return to it herethat it now appears[34] that the far-reaching conclusions drawn by deVries from his observations on the Evening Primrose, _Oenotheralamarckiana_, rest upon a very insecure foundation. The plant fromwhich de Vries saw numerous "species"--his "mutations"--arise was not, as he assumed, a _wild species_ that had been introduced to Europefrom America, but was probably a hybrid form which was firstdiscovered in the Jardin des Plantes in Paris, and which does notappear to exist anywhere in America as a wild species. 

This gives a severe shock to the "Mutation theory, " for the other_actually wild_ species with which de Vries experimented showed no"mutations" but yielded only negative results. 

Thus we come to the conclusion that Darwin[35] was right in regardingtransformations as taking place by minute steps, which, if useful, areaugmented in the course of innumerable generations, because theirpossessors more frequently survive in the struggle for existence. 

(_b_) _Selection-value of the initial steps_

Is it possible that the insignificant deviations which we know as"individual variations" can form the beginning of a process ofselection? Can they decide which is to perish and which to survive? Touse a phrase of Romanes, can they have _selection-value_?

Darwin himself answered this question, and brought together manyexcellent examples to show that differences, apparently insignificantbecause very small, might be of decisive importance for the life ofthe possessor. But it is by no means enough to bring forward cases ofthis kind, for the question is not merely whether finished adaptationshave selection-value, but whether the first beginnings of these, andwhether the small, I might almost say minimal increments, which haveled up from these beginnings to the perfect adaptation, have also hadselection-value. To this question even one who, like myself, has beenfor many years a convinced adherent of the theory of selection, canonly reply: _We must assume so, but we cannot prove it in any case_. It is not upon demonstrative evidence that we rely when we championthe doctrine of selection as a scientific truth; we base our argumenton quite other grounds. Undoubtedly there are many apparentlyinsignificant features, which can nevertheless be shown to beadaptations--for instance, the thickness of the basin-shaped shell ofthe limpets that live among the breakers on the shore. There can be nodoubt that the thickness of these shells, combined with their flatforms, protects the animals from the force of the waves breaking uponthem, --but how have they become so thick? What proportion of thicknesswas sufficient to decide that of two variants of a limpet one shouldsurvive, the other be eliminated? We can say nothing more than that weinfer from the present state of the shell, that it must have varied inregard to differences in shell-thickness, and that these differencesmust have had selection-value, --no proof therefore, but an assumptionwhich we must show to be convincing. 

For a long time the marvellously complex _radiate_ and _lattice-work_skeletons of Radiolarians were regarded as a mere outflow of "Nature'sinfinite wealth of form, " as an instance of a purely morphologicalcharacter with no biological significance. But recent investigationshave shown that these, too, have an adaptive significance (Häcker). The same thing has been shown by Schütt in regard to the lowlyunicellular plants, the Peridineae, which abound alike on the surfaceof the ocean and in its depths. It has been shown that the longskeletal processes which grow out from these organisms havesignificance not merely as a supporting skeleton, but also as anextension of the superficial area, which increases the contact withthe water-particles, and prevents the floating organisms from sinking. It has been established that the processes are considerably shorter inthe colder layers of the ocean, and that they may be twelve times aslong[36] in the warmer layers, thus corresponding to the greater orsmaller amount of friction which takes place in the denser and lessdense layers of the water. 

The Peridineae of the warmer ocean layers have thus become long-rayed, those of the colder layers short-rayed, not through the direct effectof friction on the protoplasm, but through processes of selection, which favoured the longer rays in warm water, since they kept theorganism afloat, while those with short rays sank and were eliminated. If we put the question as to selection-value in this case, and ask howgreat the variations in the length of processes must be in order topossess selection-value; what can we answer except that thesevariations must have been minimal, and yet sufficient to prevent toorapid sinking and consequent elimination? Yet this very case wouldgive the ideal opportunity for a mathematical calculation of theminimal selection-value, although of course it is not feasible fromlack of data to carry out the actual calculation. 

But even in organisms of more than microscopic size there mustfrequently be minute, even microscopic differences which set going theprocess of selection, and regulate its progress to the highestpossible perfection. 

Many tropical trees possess thick, leathery leaves, as a protectionagainst the force of the tropical raindrops. The _direct_ influence ofthe rain cannot be the cause of this power of resistance, for theleaves, while they were still thin, would simply have been torn topieces. Their toughness must therefore be referred to selection, whichwould favour the trees with slightly thicker leaves, though we cannotcalculate with any exactness how great the first stages of increase inthickness must have been. Our hypothesis receives further support fromthe fact that, in many such trees, the leaves are drawn out into abeak-like prolongation (Stahl and Haberlandt) which facilitates therapid falling off of the rain water, and also from the fact that theleaves, while they are still young, hang limply down in bunches whichoffer the least possible resistance to the rain. Thus there are herethree adaptations which can only be interpreted as due to selection. The initial stages of these adaptations must undoubtedly have hadselection-value. 

But even in regard to this case we are reasoning in a circle, notgiving "proofs, " and no one who does not wish to believe in theselection-value of the initial stages can be forced to do so. Amongthe many pieces of presumptive evidence a particularly weighty oneseems to me to be _the smallness of the steps of progress_ which wecan observe in certain cases, as for instance in leaf-imitation amongbutterflies, and in mimicry generally. The resemblance to a leaf, forinstance of a particular Kallima, seems to us so close as to bedeceptive, and yet we find in another individual, or it may be in manyothers, a spot added which increases the resemblance, and which couldnot have become fixed unless the increased deceptiveness so producedhad frequently led to the overlooking of its much persecutedpossessor. But if we take the selection-value of the initial stagesfor granted, we are confronted with the further question which Imyself formulated many years ago: How does it happen _that thenecessary beginnings of a useful variation are always present_? Howcould insects which live upon or among green leaves become all green, while those that live on bark become brown? How have the desertanimals become yellow and the Arctic animals white? Why were thenecessary variations always present? How could the green locust laybrown eggs, or the privet caterpillar develop white and lilac-colouredlines on its green skin?

It is of no use answering to this that the question is wronglyformulated[37] and that it is the converse that is true; that theprocess of selection takes place in accordance with the variationsthat present themselves. This proposition is undeniably true, but soalso is another, which apparently negatives it: the variation requiredhas in the majority of cases actually presented itself. Selectioncannot solve this contradiction; it does not call forth the usefulvariation, but simply works upon it. The ultimate reason why one andthe same insect should occur in green and in brown, as often happensin caterpillars and locusts, lies in the fact that variations towardsbrown presented themselves, and so also did variations towards green:_the kernel of the riddle lies in the varying_, and for the present wecan only say, that small variations in different directions presentthemselves in every species. Otherwise so many different kinds ofvariations could not have arisen. I have endeavoured to explain thisremarkable fact by means of the intimate processes that must takeplace within the germ-plasm, and I shall return to the problem whendealing with "germinal selection. "

We have, however, to make still greater demands on variation, for itis not enough that the necessary variation should occur in isolatedindividuals, because in that case there would be small prospect of itsbeing preserved, notwithstanding its utility. Darwin at firstbelieved, that even single variations might lead to transformation ofthe species, but later he became convinced that this was impossible, at least without the coöperation of other factors, such as isolationand sexual selection. 

In the case of the _green caterpillars with bright longitudinalstripes_, numerous individuals exhibiting this useful variation musthave been produced to start with. In all higher, that is, multicellular organisms, the germ-substance is the source of alltransmissible variations, and this germ-plasm is not a simplesubstance but is made up of many primary constituents. The questioncan therefore be more precisely stated thus: How does it come aboutthat in so many cases the useful variations present themselves innumbers just where they are required, the white oblique lines in theleaf-caterpillar on the under surface of the body, the accompanyingcoloured stripes just above them? And, further, how has it come aboutthat in grass caterpillars, not oblique but longitudinal stripes, which are more effective for concealment among grass and plants, havebeen evolved? And finally, how is it that the same Hawk-mothcaterpillars, which to-day show oblique stripes, possessedlongitudinal stripes in Tertiary times? We can read this fact from thehistory of their development, and I have before attempted to show thebiological significance of this change of colour. [38]

For the present I need only draw the conclusion that one and the samecaterpillar may exhibit the initial stages of both, and that itdepends on the manner in which these marking elements are_intensified_ and _combined_ by natural selection whether whitishlongitudinal or oblique stripes should result. In this case then the"useful variations" were actually "always there, " and we see that inthe same group of Lepidoptera, e. G. Species of Sphingidae, evolutionhas occurred in both directions according to whether the form livedamong grass or on broad leaves with oblique lateral veins, and we canobserve even now that the species with oblique stripes havelongitudinal stripes when young, that is to say, while the stripeshave no biological significance. The white places in the skin whichgave rise, probably first as small spots, to this protective markingcould be combined in one way or another according to the requirementsof the species. They must therefore either have possessedselection-value from the first, or, if this was not the case at theirearliest occurrence, there must have been _some other factors_ whichraised them to the point of selection-value. I shall return to this indiscussing germinal selection. But the case may be followed stillfarther, and leads us to the same alternative on a still more securebasis. 

Many years ago I observed in caterpillars of _Smerinthus populi_ (thepoplar hawk-moth), which also possess white oblique stripes, thatcertain individuals showed _red spots_ above these stripes; thesespots occurred only on certain segments, and never flowed together toform continuous stripes. In another species (_Smerinthus tiliae_)similar blood-red spots unite to form a line-like coloured seam in thelast stage of larval life, while in _S. Ocellata_ rust-red spotsappear in individual caterpillars, but more rarely than in _S. Populi_, and they show no tendency to flow together. 

Thus we have here the origin of a new character, arising from smallbeginnings, at least in _S. Tiliae_, in which species the colouredstripes are a normal specific character. In the other species, _S. Populi_ and _S. Ocellata_, we find the beginnings of the samevariation, in one more rarely than in the other, and we can imaginethat, in the course of time, in these two species, coloured lines overthe oblique stripes will arise. In any case these spots are theelements of variation, out of which coloured lines _may_ be evolved, if they are combined in this direction through the agency of naturalselection. In _S. Populi_ the spots are often small, but sometimes itseems as though several had united to form large spots. Whether aprocess of selection in this direction will arise in _S. Populi_ and_S. Ocellata_, or whether it is now going on cannot be determined, since we cannot tell in advance what biological value the markingmight have for these two species. It is conceivable that the spots mayhave no selection-value as far as these species are concerned, and maytherefore disappear again in the course of phylogeny, or, on the otherhand, that they may be changed in another direction, for instancetowards imitation of the rust-red fungoid patches on poplar and willowleaves. In any case we may regard the smallest spots as the initialstages of variation, the larger as a cumulative summation of these. Therefore either these initial stages must already possessselection-value, or, as I said before: _There must be some otherreason for their cumulative summation_. I should like to give one moreexample, in which we can infer, though we cannot directly observe, theinitial stages. 

All the Holothurians or sea-cucumbers have in the skin calcereousbodies of different forms, usually thick and irregular, which make theskin tough and resistant. In a small group of them--the species ofSynapta--the calcareous bodies occur in the form of delicate anchorsof microscopic size. Up till 1897 these anchors, like many otherdelicate microscopic structures, were regarded as curiosities, asnatural marvels. But a Swedish observer, Oestergren, has recentlyshown that they have a biological significance: they serve thefootless Synapta as auxiliary organs of locomotion, since, when thebody swells up in the act of creeping, they press firmly with theirtips, which are embedded in the skin, against the substratum on whichthe animal creeps, and thus prevent slipping backwards. In otherHolothurians this slipping is made impossible by the fixing of thetube-feet. The anchors act automatically, sinking their tips towardsthe ground when the corresponding part of the body thickens, andreturning to the original position at an angle of 45 degrees to theupper surface when the part becomes thin again. The arms of the anchordo not lie in the same plane as the shaft, and thus the curve of thearms forms the outermost part of the anchor, and offers no furtherresistance to the gliding of the animal. Every detail of the anchor, the curved portion, the little teeth at the head, the arms, etc. , canbe interpreted in the most beautiful way, above all the form of theanchor itself, for the two arms prevent it from swaying round to theside. The position of the anchors, too, is definite and significant;they lie obliquely to the longitudinal axis of the animal, andtherefore they act alike whether the animal is creeping backwards orforwards. Moreover, the tips would pierce through the skin if theanchors lay in the longitudinal direction. Synapta burrows in thesand; it first pushes in the thin anterior end, and thickens thisagain, thus enlarging the hole, then the anterior tentacles displacemore sand, the body is worked in a little farther, and the processbegins anew. In the first act the anchors are passive, but they beginto take an active share in the forward movement when the body iscontracted again. Frequently the animal retains only the posterior endburied in the sand, and then the anchors keep it in position, and makerapid withdrawal possible. 

Thus we have in these apparently random forms of the calcereousbodies, complex adaptations in which every little detail as todirection, curve, and pointing is exactly determined. That they haveselection-value in their present perfected form is beyond all doubt, since the animals are enabled by means of them to bore rapidly intothe ground and so to escape from enemies. We do not know what theinitial stages were, but we cannot doubt that the little improvements, which occurred as variations of the originally simple slimy bodies ofthe Holothurians, were preserved because they already possessedselection-value for the Synaptidae. For such minute microscopicstructures whose form is so delicately adapted to the rôle they haveto play in the life of the animal, cannot have arisen suddenly and asa whole, and every new variation of the anchor, that is, in thedirection of the development of the two arms, and every curving of theshaft which prevented the tips from projecting at the wrong time, inshort, every little adaptation in the modelling of the anchor musthave possessed selection-value. And that such minute changes of formfall within the sphere of fluctuating variations, that is to say, _that they occur_ is beyond all doubt. 

In many of the Synaptidae the anchors are replaced by calcareous rodsbent in the form of an S, which are said to act in the same way. Others, such as those of the genus Ankyroderma, have anchors whichproject considerably beyond the skin, and, according to Oestergren, serve "to catch plant-particles and other substances" and so mask theanimal. Thus we see that in the Synaptidae the thick and irregularcalcareous bodies of the Holothurians have been modified andtransformed in various ways in adaptation to the footlessness of theseanimals, and to the peculiar conditions of their life, and we mustconclude that the earlier stages of these changes presented themselvesto the processes of selection in the form of microscopic variations. For it is as impossible to think of any origin other than throughselection in this case as in the case of the toughness, and the"drip-tips" of tropical leaves. And as these last could not have beenproduced directly by the beating of the heavy raindrops upon them, sothe calcareous anchors of Synapta cannot have been produced directlyby the friction of the sand and mud at the bottom of the sea, and, since they are parts whose function is _passive_ the Lamarckian factorof use and disuse does not come into question. The conclusion isunavoidable, that the microscopically small variations of thecalcareous bodies in the ancestral forms have been intensified andaccumulated in a particular direction, till they have led to theformation of the anchor. Whether this has taken place by the action ofnatural selection alone, or whether the laws of variation and theintimate processes within the germ-plasm have coöperated will becomeclear in the discussion of germinal selection. This whole process ofadaptation has obviously taken place within the time that has elapsedsince this group of sea-cucumbers lost their tube-feet, thosecharacteristic organs of locomotion which occur in no group except theEchinoderms, and yet have totally disappeared in the Synaptidae. Andafter all what would animals that live in sand and mud do withtube-feet?

(_c_) _Coadaptation_

Darwin pointed out that one of the essential differences betweenartificial and natural selection lies in the fact that the former canmodify only a few characters, usually only one at a time, while Naturepreserves in the struggle for existence all the variations of aspecies, at the same time and in a purely mechanical way, if theypossess selection-value. 

Herbert Spencer, though himself an adherent of the theory of selection, declared in the beginning of the nineties that in his opinion the range ofthis principle was greatly over-estimated, if the great changes which havetaken place in so many organisms in the course of ages are to beinterpreted as due to this process of selection alone, since notransformation of any importance can be evolved by itself; it is alwaysaccompanied by a host of secondary changes. He gives the familiar exampleof the Giant Stag of the Irish peat, the enormous antlers of which requirednot only a much stronger skull cap, but also greater strength of thesinews, muscles, nerves and bones of the whole anterior half of the animal, if their mass was not to weigh down the animal altogether. It isinconceivable, he says, that so many processes of selection should takeplace _simultaneously_, and we are therefore forced to fall back on theLamarckian factor of the use and disuse of functional parts. And how, heasks, could natural selection follow two opposite directions of evolutionin different parts of the body at the same time, as for instance in thecase of the kangaroo, in which the forelegs must have become shorter, whilethe hind legs and the tail were becoming longer and stronger?

Spencer's main object was to substantiate the validity of theLamarckian principle, the coöperation of which with selection had beendoubted by many. And it does seem as though this principle, if itoperates in nature at all, offers a ready and simple explanation ofall such secondary variations. Not only muscles, but nerves, bones, sinews, in short all tissues which function actively, increase instrength in proportion as they are used, and conversely they decreasewhen the claims on them diminish. All the parts, therefore, whichdepend on the part that varied first, as for instance the enlargedantlers of the Irish Elk, must have been increased or decreased instrength, in exact proportion to the claims made upon them, --just asis actually the case. 

But beautiful as this explanation would be, I regard it as untenable, because it assumes the _transmissibility of functional modifications_(so-called "acquired" characters), and this is not onlyundemonstrable, but is scarcely theoretically conceivable, for thesecondary variations which accompany or follow the first ascorrelative variations, occur also in cases in which the animalsconcerned are sterile and _therefore cannot transmit anything to theirdescendants_. This is true of _worker bees_, and particularly of_ants_, and I shall here give a brief survey of the present state ofthe problem as it appears to me. 

Much has been written on both sides of this question since thepublished controversy on the subject in the nineties between HerbertSpencer and myself. I should like to return to the matter in detail, if the space at my disposal permitted, because it seems to me that thearguments I advanced at that time are equally cogent to-day, notwithstanding all the objections that have since been urged againstthem. Moreover, the matter is by no means one of subordinate interest;it is the very kernel of the whole question of the reality and valueof the principle of selection. For if selection alone does not sufficeto explain "_harmonious adaptation_" as I have called Spencer's_Coadaptation_, and if we require to call in the aid of the Lamarckianfactor it would be questionable whether selection would explain anyadaptations whatever. In this particular case--of worker bees--theLamarckian factor may be excluded altogether, for it can bedemonstrated that here at any rate the effects of use and disusecannot be transmitted. 

But if it be asked why we are unwilling to admit the coöperation ofthe Darwinian factor of selection and the Lamarckian factor, sincethis would afford us an easy and satisfactory explanation of thephenomena, I answer: _Because the Lamarckian principle is fallacious, and because by accepting it we close the way towards deeper insight_. It is not a spirit of combativeness or a desire for self-vindicationthat induces me to take the field once more against the Lamarckianprinciple, it is the conviction that the progress of our knowledge isbeing obstructed by the acceptance of this fallacious principle, sincethe facile explanation it apparently affords prevents our seekingafter a truer explanation and a deeper analysis. 

The workers in the various species of ants are sterile, that is tosay, they take no regular part in the reproduction of the species, although individuals among them may occasionally lay eggs. In additionto this they have lost the wings, and the _receptaculum seminis_, andtheir compound eyes have degenerated to a few facets. How could thislast change have come about through disuse, since the eyes of workersare exposed to light in the same way as are those of the sexualinsects and thus in this particular case are not liable to "disuse" atall? The same is true of the _receptaculum seminis_, which can onlyhave been disused as far as its glandular portion and its stalk areconcerned, and also of the wings, the nerves tracheae and epidermalcells of which could not cease to function until the whole wing haddegenerated, for the chitinous skeleton of the wing does not functionat all in the active sense. 

But, on the other hand, the workers in all species have undergonemodifications in a positive direction, as, for instance, the greaterdevelopment of brain. In many species large workers have evolved, --theso-called _soldiers_, with enormous jaws and teeth, which defend thecolony, --and in others there are _small_ workers which have taken overother special functions, such as the rearing of the young Aphides. This kind of division of the workers into two castes occurs amongseveral tropical species of ants, but it is also present in theItalian species, _Colobopsis truncata_. Beautifully as the size of thejaws could be explained as due to the increased use made of them bythe "soldiers, " or the enlarged brain as due to the mental activitiesof the workers, the fact of the infertility of these forms is aninsurmountable obstacle to accepting such an explanation. Neither jawsnor brain can have been evolved on the Lamarckian principle. 

The problem of coadaptation is no easier in the case of the ant thanin the case of the Giant Stag. Darwin himself gave a prettyillustration to show how imposing the difference between the two kindsof workers in one species would seem if we translated it into humanterms. In regard to the Driver ants (Anomma) we must picture toourselves a piece of work, "for instance the building of a house, being carried on by two kinds of workers, of which one group was fivefeet four inches high, the other sixteen feet high. "[39]

Although the ant is a small animal as compared with man or with theIrish Elk, the "soldier" with its relatively enormous jaws is hardlyless heavily burdened than the Elk with its antlers, and in the ant'scase, too, a strengthening of the skeleton, of the muscles, the nervesof the head, and of the legs must have taken place parallel with theenlargement of the jaws. _Harmonious adaptation_ (coadaptation) hashere been active in a high degree, and yet these "soldiers" aresterile! There thus remains nothing for it but to refer all theiradaptations, positive and negative alike, to processes of selectionwhich have taken place in the rudiments of the workers within the eggand sperm-cells of their parents. There is no way out of thedifficulty except the one Darwin pointed out. He himself did not findthe solution of the riddle at once. At first he believed that the caseof the workers among social insects presented "the most seriousspecial difficulty" in the way of his theory of natural selection; andit was only after it had become clear to him that it was not thesterile insects themselves but their parents that were selected, according as they produced more or less well adapted workers, that hewas able to refer to this very case of the conditions among ants "_inorder to show the power of natural selection_. "[40] He explains hisview by a simple but interesting illustration. Gardeners haveproduced, by means of long continued artificial selection, a varietyof Stock, which bears entirely double, and therefore infertileflowers. [41] Nevertheless the variety continues to be reproduced fromseed, because, in addition to the double and infertile flowers, theseeds always produce a certain number of single, fertile blossoms, andthese are used to reproduce the double variety. These single andfertile plants correspond "to the males and females of an ant-colony, the infertile plants, which are regularly produced in large numbers, to the neuter workers of the colony. "

This illustration is entirely apt, the only difference between thetwo cases consisting in the fact that the variation in the flower isnot a useful, but a disadvantageous one, which can only be preservedby artificial selection on the part of the gardener, while thetransformations that have taken place parallel with the sterility ofthe ants are useful, since they procure for the colony an advantage inthe struggle for existence, and they are therefore preserved bynatural selection. Even the sterility itself in this case is notdisadvantageous, since the fertility of the true females has at thesame time considerably increased. We may therefore regard the sterileforms of ants, which have gradually been adapted in several directionsto varying functions, _as a certain proof_ that selection really takesplace in the germ-cells of the fathers and mothers of the workers, andthat _special complexes of primordia_ (_ids_) are present in theworkers and in the males and females, and these complexes contain theprimordia of the individual parts (_determinants_). But since allliving entities vary, the determinants must also vary, now in afavourable, now in an unfavourable direction. If a female produceseggs, which contain favourably varying determinants in the worker-ids, then these eggs will give rise to workers modified in the favourabledirection, and if this happens with many females, the colony concernedwill contain a better kind of worker than other colonies. 

I digress here in order to give an account of the intimate processes, which, according to my view, take place within the germ-plasm, andwhich I have called "_germinal selection_. " These processes are ofimportance since they form the roots of variation, which in its turnis the root of natural selection. I cannot here do more than give abrief outline of the theory in order to show how the Darwin-Wallacetheory of selection has gained support from it. 

With others, I regard the minimal amount of substance which iscontained within the nucleus of the germ-cells, in the form of rods, bands, or granules, as the _germ-substance_ or _germ-plasm_, and Icall the individual granules _ids_. There is always a multiplicity ofsuch ids present in the nucleus, either occurring individually, orunited in the form of rods or bands (chromosomes). Each id containsthe primary constituents of a _whole_ individual, so that several idsare concerned in the development of a new individual. 

In every being of complex structure thousands of primary constituentsmust go to make up a single id; these I call _determinants_, and Imean by this name very small individual particles, far below thelimits of microscopic visibility, vital units which feed, grow, andmultiply by division. These determinants control the parts of thedeveloping embryo, --in what manner need not here concern us. Thedeterminants differ among themselves, those of a muscle aredifferently constituted from those of a nerve-cell or a glandularcell, etc. , and every determinant is in its turn made up of minutevital units, which I call _biophores_, or the bearers of life. According to my view, these determinants not only assimilate, likeevery other living unit, but they _vary_ in the course of theirgrowth, as every living unit does; they may vary qualitatively if theelements of which they are composed vary, they may grow and dividemore or less rapidly, and their variations give rise to_corresponding_ variations of the organ, cell, or cell-group whichthey determine. That they are undergoing ceaseless fluctuations inregard to size and quality seems to me the inevitable consequence oftheir unequal nutrition; for although the germ-cell as a whole usuallyreceives sufficient nutriment, minute fluctuations in the amountcarried to different parts within the germ-plasm cannot fail to occur. 

Now, if a determinant, for instance of a sensory cell, receives for aconsiderable time more abundant nutriment than before, it will growmore rapidly--become bigger, and divide more quickly, and, later, whenthe id concerned develops into an embryo, this sensory cell willbecome stronger than in the parents, possibly even twice as strong. This is an instance of a _hereditary individual variation_, arisingfrom the germ. 

The nutritive stream which, according to our hypothesis, favours thedeterminant _N_ by chance, that is, for reasons unknown to us, mayremain strong for a considerable time, or may decrease again; but evenin the latter case it is conceivable that the ascending movement ofthe determinant may continue, because the strengthened determinant now_actively_ nourishes itself more abundantly, --that is to say, itattracts the nutriment to itself, and to a certain extent withdraws itfrom its fellow-determinants. In this way, it may--as it seems tome--get into _permanent upward movement, and attain a degree ofstrength from which there is no falling back_. Then positive ornegative selection sets in, favouring the variations which areadvantageous, setting aside those which are disadvantageous. 

In a similar manner a _downward_ variation of the determinants maytake place, if its progress be started by a diminished flow ofnutriment. The determinants which are weakened by this diminished flowwill have less affinity for attracting nutriment because of theirdiminished strength, and they will assimilate more feebly and growmore slowly, unless chance streams of nutriment help them to recoverthemselves. But, as will presently be shown, a change of directioncannot take place at _every_ stage of the degenerative process. If acertain critical stage of downward progress be passed, even favourableconditions of food-supply will no longer suffice permanently to changethe direction of the variation. Only two cases are conceivable; if thedeterminant corresponds to a _useful_ organ, only its removal canbring back the germ-plasm to its former level; therefore personalselection removes the id in question, with its determinants, from thegerm-plasm, by causing the elimination of the individual in thestruggle for existence. But there is another conceivable case; thedeterminants concerned may be those of an organ which has become_useless_, and they will then continue unobstructed, but withexceeding slowness, along the downward path, until the organ becomesvestigial, and finally disappears altogether. 

The fluctuations of the determinants hither and thither may thus betransformed into a lasting ascending or descending movement; and _thisis the crucial point of these germinal processes_. 

This is not a fantastic assumption; we can read it in the fact of thedegeneration of disused parts. _Useless organs are the only ones whichare not helped to ascend again by personal selection, and therefore intheir case alone can we form any idea of how the primary constituentsbehave, when they are subject solely to intra-germinal forces_. 

The whole determinant system of an id, as I conceive it, is in a stateof continual fluctuation upwards and downwards. In most cases thefluctuations will counteract one another, because the passive streamsof nutriment soon change, but in many cases the limit from which areturn is possible will be passed, and then the determinants concernedwill continue to vary in the same direction, till they attain positiveor negative selection-value. At this stage personal selectionintervenes and sets aside the variation if it is disadvantageous, orfavours--that is to say, preserves--it if it is advantageous. Only_the determinant of a useless organ is uninfluenced by personalselection_, and, as experience shows, it sinks downwards; that is, theorgan that corresponds to it degenerates very slowly butuninterruptedly till, after what must obviously be an immense stretchof time, it disappears from the germ-plasm altogether. 

Thus we find in the fact of the degeneration of disused parts theproof that not all the fluctuations of a determinant return toequilibrium again, but that, when the movement has attained to acertain strength, it continues _in the same direction_. We have entirecertainty in regard to this as far as the downward progress isconcerned, and we must assume it also in regard to ascendingvariations, as the phenomena of artificial selection certainly justifyus in doing. If the Japanese breeders were able to lengthen thetail-feathers of the cock to six feet, it can only have been becausethe determinants of the tail-feathers in the germ-plasm had alreadystruck out a path of ascending variation, and this movement was takenadvantage of by the breeder, who continually selected for reproductionthe individuals in which the ascending variation was most marked. Forall breeding depends upon the unconscious selection of germinalvariations. 

Of course these germinal processes cannot be proved mathematically, since we cannot actually see the play of forces of the passivefluctuations and their causes. We cannot say how great thesefluctuations are, and how quickly or slowly, how regularly orirregularly they change. Nor do we know how far a determinant must bestrengthened by the passive flow of the nutritive stream if it is tobe beyond the danger of unfavourable variations, or how far it must beweakened passively before it loses the power of recovering itself byits own strength. It is no more possible to bring forward actualproofs in this case than it was in regard to the selection-value ofthe initial stages of an adaptation. But if we consider that allheritable variations must have their roots in the germ-plasm, andfurther, that when personal selection does not intervene, that is tosay, in the case of parts which have become useless, a degeneration ofthe part, and therefore also of its determinant must inevitably takeplace; then we must conclude that processes such as I have assumed arerunning their course within the germ-plasm, and we can do this with asmuch certainty as we were able to infer, from the phenomena ofadaptation, the selection-value of their initial stages. The fact ofthe degeneration of disused parts seems to me to afford irrefutableproof that the fluctuations within the germ-plasm _are the real rootof all hereditary variation_, and the preliminary condition for theoccurrence of the Darwin-Wallace factor of selection. Germinalselection supplies the stones out of which personal selection buildsher temples and palaces: _adaptations_. The importance for the theoryof the process of degeneration of disused parts cannot beover-estimated, especially when it occurs in sterile animal forms, where we are free from the doubt as to the alleged _Lamarckian factor_which is apt to confuse our ideas in regard to other cases. 

If we regard the variation of the many determinants concerned in thetransformation of the female into the sterile worker as having comeabout through the gradual transformation of the ids into worker-ids, we shall see that the germ-plasm of the sexual ants must contain threekinds of ids, male, female, and worker ids, or if the workers havediverged into soldiers and nest-builders, then four kinds. Weunderstand that the worker-ids arose because their determinants struckout a useful path of variation, whether upward or downward, and thatthey continued in this path until the highest attainable degree ofutility of the parts determined was reached. But in addition to theorgans of positive or negative selection-value, there were some whichwere indifferent as far as the success and especially the functionalcapacity of the workers was concerned: wings, ovarian tubes, _receptaculum seminis_, a number of the facets of the eye, perhapseven the whole eye. As to the ovarian tubes it is is possible thattheir degeneration was an advantage for the workers, in saving energy, and if so selection would favour the degeneration; but how could thepresence of eyes diminish the usefulness of the workers to the colony?or the minute _receptaculum seminis_, or even the wings? These partshave therefore degenerated _because they were of no further value tothe insect_. But if selection did not influence the setting aside ofthese parts because they were neither of advantage nor of disadvantageto the species, then the Darwinian factor of selection is hereconfronted with a puzzle which it cannot solve alone, but which atonce becomes clear when germinal selection is added. For thedeterminants of organs that have no further value for the organism, must, as we have already explained, embark on a gradual course ofretrograde development. 

In ants the degeneration has gone so far that there are nowing-rudiments present in _any_ species, as is the case with so manybutterflies, flies, and locusts, but in the larvae the imaginablediscs of the wings are still laid down. With regard to the ovaries, degeneration has reached different levels in different species ofants, as has been shown by the researches of my former pupil, Elizabeth Bickford. In many species there are twelve ovarian tubes, and they decrease from that number to one; indeed, in one species noovarian tube at all is present. So much at least is certain from whathas been said, that in this case _everything_ depends on thefluctuations of the elements of the germ-plasm. Germinal selection, here as elsewhere, presents the variations of the determinants, andpersonal selection favours or rejects these, or, --if it be a questionof organs which have become useless, --it does not come into play atall, and allows the descending variation free course. 

It is obvious that even the problem of _coadaptation in sterileanimals_ can thus be satisfactorily explained. If the determinants areoscillating upwards and downwards in continual fluctuation, andvarying more pronouncedly now in one direction now in the other, useful variations of every determinant will continually presentthemselves anew, and may, in the course of generations, be combinedwith one another in various ways. But there is one character of thedeterminants that greatly facilitates this complex process ofselection, that, after a certain limit has been reached, they go onvarying in the same direction. From this it follows that developmentalong a path once struck out may proceed without the continualintervention of personal selection. This factor only operates, so tospeak, at the beginning, when it selects the determinants which arevarying in the right direction, and again at the end, when it isnecessary to put a check upon further variation. In addition to this, enormously long periods have been available for all these adaptations, as the very gradual transition stages between females and workers inmany species plainly show, and thus this process of transformationloses the marvellous and mysterious character that seemed at the firstglance to invest it, and takes rank, without any straining, among theother processes of selection. It seems to me that, from the facts thatsterile animal forms can adapt themselves to new vital functions, their superfluous parts degenerate, and the parts more used adaptthemselves in an ascending direction, those less used in a descendingdirection, we must draw the conclusion that harmonious adaptation herecomes about _without the coöperation of the Lamarckian principle_. This conclusion once established, however, we have no reason to referthe thousands of cases of harmonious adaptation, which occur inexactly the same way among other animals or plants, to a principle, the _active intervention of which in the transformation of species isnowhere proved. We do not require it to explain the facts, andtherefore we must not assume it. _

The fact of coadaptation, which was supposed to furnish the strongestargument against the principle of selection, in reality yields theclearest evidence in favour of it. We _must_ assume it, _because noother possibility of explanation is open to us, and because theseadaptations actually exist, that is to say, have really taken place_. With this conviction I attempted, as far back as 1894, when the ideaof germinal selection had not yet occurred to me, to make "harmoniousadaptation" (coadaptation) more easily intelligible in some way orother, and so I was led to the idea, which was subsequently expoundedin detail by Baldwin, and Lloyd Morgan, and also by Osborn, and Gulickas _Organic Selection_. It seemed to me that it was not necessary thatall the germinal variations required for secondary variations shouldhave occurred _simultaneously_, since, for instance, in the case ofthe stag, the bones, muscles, sinews, and nerves would be incited bythe increasing heaviness of the antlers to greater activity in _theindividual life_, and so would be strengthened. The antlers can onlyhave increased in size by very slow degrees, so that the muscles andbones may have been able to keep pace with their growth in theindividual life, until the requisite germinal variations presentedthemselves. In this way a disharmony between the increasing weight ofthe antlers and the parts which support and move them would beavoided, since time would be given for the appropriate germinalvariations to occur, and so to set agoing the _hereditary_ variationof the muscles, sinews and bones. [42]

I still regard this idea as correct, but I attribute less importanceto "organic selection" than I did at that time, in so far that I donot believe that it _alone_ could effect complex harmoniousadaptations. Germinal selection now seems to me to play the chief partin bringing about such adaptations. Something the same is true of theprinciple I have called _Panmixia_. As I became more and moreconvinced, in the course of years, that the _Lamarckian principle_ought not to be called in to explain the dwindling of disused parts, Ibelieved that this process might be simply explained as due to thecessation of the conservative effect of natural selection. I said tomyself that, from the moment in which a part ceases to be of use, natural selection withdraws its hand from it, and then it mustinevitably fall from the height of its adaptiveness, because inferiorvariants would have as good a chance of persisting as better ones, since all grades of fitness of the part in question would be mingledwith one another indiscriminately. This is undoubtedly true, asRomanes pointed out ten years before I did, and this mingling of thebad with the good probably does bring about a deterioration of thepart concerned. But it cannot account for the steady diminution, whichalways occurs when a part is in process of becoming rudimentary, andwhich goes on until it ultimately disappears altogether. The processof dwindling cannot therefore be explained as due to panmixia alone:we can only find a sufficient explanation in germinal selection. 

IV. DERIVATIVES OF THE THEORY OF SELECTION

The impetus in all directions given by Darwin through his theory ofselection has been an immeasurable one, and its influence is stillfelt. It falls within the province of the historian of science toenumerate all the ideas which, in the last quarter of the nineteenthcentury, grew out of Darwin's theories, in the endeavour to penetratemore deeply into the problem of the evolution of the organic world. Within the narrow limits to which this paper is restricted, I cannotattempt to discuss any of these. 

V. ARGUMENTS FOR THE REALITY OF THE PROCESSES OF SELECTION

(_a_) _Sexual Selection_

Sexual selection goes hand in hand with natural selection. From thevery first I have regarded sexual selection as affording an extremelyimportant and interesting corroboration of natural selection, but, singularly enough, it is precisely against this theory that an adversejudgment has been pronounced in so many quarters, and it is only quiterecently, and probably in proportion as the wealth of facts in proofof it penetrates into a wider circle, that we seem to be approaching amore general recognition of this side of the problem of adaptations. Thus Darwin's words in his preface to the second edition (1874) of hisbook, _The Descent of Man and Sexual Selection_, are being justified:"My conviction as to the operation of natural selection remainsunshaken, " and further, "If naturalists were to become more familiarwith the idea of sexual selection, it would, I think, be accepted to amuch greater extent, and already it is fully and favourably acceptedby many competent judges. " Darwin was able to speak thus because hewas already acquainted with an immense mass of facts, which, takentogether, yield overwhelming evidence of the validity of the principleof sexual selection. 

_Natural selection_ chooses out for reproduction the individuals thatare best equipped for the struggle for existence, and it does so atevery stage of development; it thus improves the species in all itsstages and forms. _Sexual selection_ operates only on individualsthat are already capable of reproduction, and does so only in relationto the attainment of reproduction. It arises from the rivalry of onesex, usually the male, for the possession of the other, usually thefemale. Its influence can therefore only _directly_ affect one sex, inthat it equips it better for attaining possession of the other. Butthe effect may extend indirectly to the female sex, and thus the wholespecies may be modified, without, however, becoming any more capableof resistance in the struggle for existence, for sexual selection onlygives rise to adaptations which are likely to give their possessor thevictory over rivals in the struggle for possession of the female, andwhich are therefore peculiar to the wooing sex: the manifold"secondary sexual characters. " The diversity of these characters is sogreat that I cannot here attempt to give anything approaching acomplete treatment of them, but I should like to give a sufficientnumber of examples to make the principle itself, in its various modesof expression, quite clear. 

One of the chief preliminary postulates of sexual selection is theunequal number of individuals in the two sexes, for if every maleimmediately finds his mate there can be no competition for thepossession of the female. Darwin has shown that, for the most part, the inequality between the sexes is due simply to the fact that thereare more males than females, and therefore the males must take somepains to secure a mate. But the inequality does not always depend onthe numerical preponderance of the males, it is often due to polygamy;for, if one male claims several females, the number of females inproportion to the rest of the males will be reduced. Since it isalmost always the males that are the wooers, we must expect to findthe occurrence of secondary sexual characters chiefly among them, andto find it especially frequent in polygamous species. And this isactually the case. 

If we were to try to guess--without knowing the facts--what means themale animals make use of to overcome their rivals in the struggle forthe possession of the female, we might name many kinds of means, butit would be difficult to suggest any which is not actually employed insome animal group of other. I begin with the mere difference instrength, through which the male of many animals is so sharplydistinguished from the female, as, for instance, the lion, walrus, "sea-elephant, " and others. Among these the males fight violently forthe possession of the female, who falls to the victor in the combat. In this simple case no one can doubt the operation of selection, andthere is just as little room for doubt as to the selection-value ofthe initial stages of the variation. Differences in bodily strengthare apparent even among human beings, although in their case thestruggle for the possession of the female is no longer decided bybodily strength alone. 

Combats between male animals are often violent and obstinate, and theemployment of the natural weapons of the species in this way has ledto perfecting of these, e. G. The tusks of the boar, the antlers of thestag, and the enormous, antler-like jaws of the stag-beetle. Hereagain it is impossible to doubt that variations in these organspresented themselves, and that these were considerable enough to bedecisive in combat, and so to lead to the improvement of the weapon. 

Among many animals, however, the females at first withdraw from themales; they are coy, and have to be sought out, and sometimes held byforce. This tracking and grasping of the females by the males hasgiven rise to many different characters in the latter, as, forinstance, the larger eyes of the male bee, and especially of the malesof the Ephemerids (May-flies), some species of which show, in additionto the usual compound eyes, large, so-called turban-eyes, so that thewhole head is covered with seeing surfaces. In these species thefemales are very greatly in the minority (1-100), and it is easy tounderstand that a keen competition for them must take place, and that, when the insects of both sexes are floating freely in the air, anunusually wide range of vision will carry with it a decidedadvantage. Here again the actual adaptations are in accordance withthe preliminary postulates of the theory. We do not know the stagesthrough which the eye has passed to its present perfected state, but, since the number of simple eyes (facets) has become very much greaterin the male than in the female, we may assume that their increase isdue to a gradual duplication of the determinants of the ommatidium inthe germ-plasm, as I have already indicated in regard to sense-organsin general. In this case, again, the selection-value of the initialstages hardly admits of doubt; better vision _directly_ securesreproduction. 

In many cases _the organ of smell_ shows a similar improvement. Manylower Crustaceans (Daphnidae) have better developed organs of smell inthe male sex. The difference is often slight and amounts only to oneor two olfactory filaments, but certain species show a difference ofnearly a hundred of these filaments (Leptodora). The same thing occursamong insects. 

We must briefly consider the clasping or grasping organs which havedeveloped in the males among many lower Crustaceans, but here naturalselection plays its part along with sexual selection, for the union ofthe sexes is an indispensable condition for the maintenance of thespecies, and as Darwin himself pointed out, in many cases the twoforms of selection merge into each other. This fact has always seemedto me to be a proof of natural selection, for, in regard to sexualselection, it is quite obvious that the victory of the best-equippedcould have brought about the improvement only of the organs concerned, the factors in the struggle, such as the eye and the olfactory organ. 

We come now to the _excitants_; that is, to the group of sexualcharacters whose origin through processes of selection has been mostfrequently called in question. We may cite the _love-calls_ producedby many male insects, such as crickets and cicadas. These could onlyhave arisen in animal groups in which the female did not rapidly fleefrom the male, but was inclined to accept his wooing from the first. Thus, notes like the chirping of the male cricket serve to entice thefemales. At first they were merely the signal which showed thepresence of a male in the neighbourhood, and the female was graduallyenticed nearer and nearer by the continued chirping. The male thatcould make himself heard to the greatest distance would obtain thelargest following, and would transmit the beginnings, and, later, theimprovement of his voice to the greatest number of descendants. Butsexual excitement in the female became associated with the hearing ofthe love-call, and then the sound-producing organ of the male began toimprove, until it attained to the emission of the long-drawn-out softnotes of the mole-cricket or the maenad-like cry of the cicadas. Icannot here follow the process of development in detail, but will callattention to the fact that the original purpose of the voice, theannouncing of the male's presence, became subsidiary, and the excitingof the female became the chief goal to be aimed at. The loudestsingers awakened the strongest excitement, and the improvementresulted as a matter of course. I conceive of the origin of bird-songin a somewhat similar manner, first as a means of enticing, then ofexciting the female. 

One more kind of secondary sexual character must here be mentioned:the odour which emanates from so many animals at the breeding season. It is possible that this odour also served at first merely to givenotice of the presence of individuals of the other sex, but it soonbecame an excitant, and as the individuals which caused the greatestdegree of excitement were preferred, it reached as high a pitch ofperfection as was possible to it. I shall confine myself here to thecomparatively recently discovered fragrance of butterflies. SinceFritz Müller found out that certain Brazilian butterflies gave offfragrance "like a flower, " we have become acquainted with many suchcases, and we now know that in all lands, not only many diurnalLepidoptera but nocturnal ones also give off a delicate odour, whichis agreeable even to man. The ethereal oil to which this fragrance isdue is secreted by the skin-cells, usually of the wing, as I showedsoon after the discovery of the _scent-scales_. This is the case inthe males; the females have no _special_ scent-scales recognisable assuch by their form, but they must, nevertheless, give off an extremelydelicate fragrance, although our imperfect organ of smell cannotperceive it, for the males become aware of the presence of a female, even at night, from a long distance off, and gather round her. We maytherefore conclude, that both sexes have long given forth a verydelicate perfume, which announced their presence to others of the samespecies, and that in many species (_not in all_) these smallbeginnings become, in the males, particularly strong scent-scales ofcharacteristic form (lute, brush, or lyre-shaped). At first thesescales were scattered over the surface of the wing, but gradually theyconcentrated themselves, and formed broad, velvety bands, or strong, prominent brushes, and they attained their highest pitch of evolutionwhen they became enclosed within pits or folds of the skin, whichcould be opened to let the delicious fragrance stream forth suddenlytowards the female. Thus in this case also we see that characters, theoriginal use of which was to bring the sexes together, and so tomaintain the species, have been evolved in the males into means forexciting the female. And we can hardly doubt, that the females aremost readily enticed to yield to the butterfly that sends out thestrongest fragrance, --that is to say, that excites them to the highestdegree. It is a pity that our organs of smell are not fine enough toexamine the fragrance of male Lepidoptera in general, and to compareit with other perfumes which attract these insects. [43] As far as wecan perceive them they resemble the fragrance of flowers, but thereare Lepidoptera whose scent suggests musk. A smell of musk is alsogiven off by several plants: it is a sexual excitant in themusk-deer, the musk-sheep, and the crocodile. 

As far as we know, then, it is perfumes similar to those of flowersthat the male Lepidoptera give off in order to entice their mates andthis is a further indication that animals, like plants, can to a largeextent meet the claims made upon them by life, and produce theadaptations which are most purposive, --a further proof, too, of myproposition that the useful variations, so to speak, are _alwaysthere_. The flowers developed the perfumes which entice theirvisitors, and the male Lepidoptera developed the perfumes which enticeand excite their mates. 

There are many pretty little problems to be solved in this connection, for there are insects, such as some flies, that are attracted bysmells which are unpleasant to us, like those from decaying flesh andcarrion. But there are also certain flowers, some orchids forinstance, which give forth no very agreeable odour, but one which isto us repulsive and disgusting; and we should therefore expect thatthe males of such insects would give off a smell unpleasant to us, butthere is no case known to me in which this has been demonstrated. 

In cases such as we have discussed, it is obvious that there is nopossible explanation except through selection. This brings us to thelast kind of secondary sexual characters, and the one in regard towhich doubt has been most frequently expressed, --decorative coloursand decorative forms, the brilliant plumage of the male pheasant, thehumming-birds, and the bird of Paradise, as well as the bright coloursof many species of butterfly, from the beautiful blue of our littleLycaenidae to the magnificent azure of the large Morphinae of Brazil. In a great many cases, though not by any means in all, the malebutterflies are "more beautiful" than the females, and in the Tropicsin particular they shine and glow in the most superb colours. I reallysee no reason why we should doubt the power of sexual selection, and Imyself stand wholly on Darwin's side. Even though we certainly cannotassume that the females exercise a conscious choice of the"handsomest" mate, and deliberate like the judges in a court ofjustice over the perfections of their wooers, we have no reason todoubt that distinctive forms (decorative feathers), and colours have aparticularly exciting effect upon the female, just as certain odourshave among animals of so many different groups, including thebutterflies. The doubts which existed for a considerable time, as aresult of fallacious experiments, as to whether the colours of flowersreally had any influence in attracting butterflies have now been setat rest through a series of more careful investigations; we now knowthat the colours of flowers are there on account of the butterflies, as Sprengel first showed, and that the blossoms of Phanerogams areselected in relation to them, as Darwin pointed out. 

Certainly it is not possible to bring forward any convincing proof ofthe origin of decorative colours through sexual selection, but thereare many weighty arguments in favour of it, and these form a body ofpresumptive evidence so strong that it almost amounts to certainty. 

In the first place, there is the analogy with other secondary sexualcharacters. If the song of birds and the chirping of the cricket havebeen evolved through sexual selection, if the penetrating odours ofmale animals, --the crocodile, the musk-deer, the beaver, thecarnivores, and, finally, the flower-like fragrances of thebutterflies have been evolved to their present pitch in this way, whyshould decorative colours have arisen in some other way? Why shouldthe eye be less sensitive to _specifically male_ colours and other_visible_ signs _enticing to the female_, than the olfactory sense tospecifically male odours, or the sense of hearing to specifically malesounds? Moreover, the decorative feathers of birds are almost alwaysspread out and displayed before the female during courtship. I haveelsewhere[44] pointed out that decorative colouring andsweet-scentedness may replace one another in Lepidoptera as well as inflowers, for just as some modestly coloured flowers (mignonette andviolet) have often a strong perfume, while strikingly coloured onesare sometimes quite devoid of fragrance, so we find that the mostbeautiful and gaily-coloured of our native Lepidoptera, the species ofVanessa, have no scent-scales, while these are often markedlydeveloped in grey nocturnal Lepidoptera. Both attractions may, however, be combined in butterflies, just as in flowers. Of course, wecannot explain why both means of attraction should exist in one genus, and only one of them in another, since we do not know the minutestdetails of the conditions of life of the genera concerned. But fromthe sporadic distribution of scent-scales in Lepidoptera, and fromtheir occurrence or absence in nearly related species, we may concludethat fragrance is a relatively _modern_ acquirement, more recent thanbrilliant colouring. 

One thing in particular that stamps decorative colouring as a productof selection is _its gradual intensification_ by the addition of newspots, which we can quite well observe, because in many cases thecolours have been first acquired by the males, and later transmittedto the females by inheritance. The scent-scales are never thustransmitted, probably for the same reason that the decorative coloursof many birds are often not transmitted to the females: because withthese they would be exposed to too great elimination by enemies. Wallace was the first to point out that in species with concealednests the beautiful feathers of the male occurred in the female also, as in the parrots, for instance, but this is not the case in specieswhich brood on an exposed nest. In the parrots one can often observethat the general brilliant colouring of the male is found in thefemale, but that certain spots of colour are absent, and these haveprobably been acquired comparatively recently by the male and have notyet been transmitted to the female. 

Isolation of the group of individuals which is in process of varyingis undoubtedly of great value in sexual selection, for even a solitaryconspicuous variation will become dominant much sooner in a smallisolated colony, than among a large number of members of a species. 

Any one who agrees with me in deriving variations from germinalselection will regard that process as an essential aid towardsexplaining the selection of distinctive courtship-characters, such ascoloured spots, decorative feathers, horny outgrowths in birds andreptiles, combs, feather-tufts, and the like, since the beginnings ofthese would be presented with relative frequency in the strugglebetween the determinants within the germ-plasm. The process oftransmission of decorative feathers to the female results, as Darwinpointed out and illustrated by interesting examples, in the_colour-transformation of a whole species_, and this process, as thephyletically older colouring of young birds shows, must, in the courseof thousands of years, have repeated itself several times in a line ofdescent. 

If we survey the wealth of phenomena presented to us by secondarysexual characters, we can hardly fail to be convinced of the truth ofthe principle of sexual selection. And certainly no one who hasaccepted natural selection should reject sexual selection, for, notonly do the two processes rest upon the same basis, but they mergeinto one another, so that it is often impossible to say how much of aparticular character depends on one and how much on the other form ofselection. 

(_b_) _Natural Selection_

An actual proof of the theory of sexual selection is out of thequestion, if only because we cannot tell when a variation attains toselection-value. It is certain that a delicate sense of smell is ofvalue to the male moth in his search for the female, but whether thepossession of one additional olfactory hair, or of ten, or of twentyadditional hairs leads to the success of its possessor we are unableto tell. And we are groping even more in the dark when we discuss theexcitement caused in the female by agreeable perfumes, or by strikingand beautiful colours. That these do make an impression is beyonddoubt; but we can only assume that slight intensifications of themgive any advantage, and we _must_ assume this _since otherwisesecondary sexual characters remain inexplicable_. 

The same thing is true in regard to natural selection. It is notpossible to bring forward any actual proof of the selection-value ofthe initial stages, and the stages in the increase of variations, ashas been already shown. But the selection-value of a finishedadaptation can in many cases be statistically determined. Cesnola andPoulton have made valuable experiments in this direction. The formerattached forty-five individuals of the green, and sixty-five of thebrown variety of the praying mantis (_Mantis religiosa_), by a silkthread to plants, and watched them for seven days. The insects whichwere on a surface of a colour Similar to their own remained uneaten, while twenty-five green insects on brown parts of plants had alldisappeared in eleven days. 

The experiments of Poulton and Sanders[45] were made with 600 pupae of_Vanessa urticae_, the "tortoise-shell butterfly. " The pupae wereartificially attached to nettles, tree-trunks, fences, walls, and tothe ground, some at Oxford, some at St. Helens in the Isle of Wight. In the course of a month 93% of the pupae at Oxford were killed, chiefly by small birds, while at St. Helens 68% perished. Theexperiments showed very clearly that the colour and character of thesurface on which the pupa rests--and thus its own conspicuousness--areof the greatest importance. At Oxford only the four pupae which werefastened to nettles emerged; all the rest--on bark, stones and thelike--perished. At St. Helens the elimination was as follows: onfences where the pupae were conspicuous, 92%; on bark, 66%; on walls, 54%; and among nettles, 57%. These interesting experiments confirm ourviews as to protective coloration, and show further, _that the ratioof elimination in the species is a very high one, and that thereforeselection must be very keen_. 

We may say that the process of selection follows as a logicalnecessity from the fulfilment of the three preliminary postulates ofthe theory: variability, heredity, and the struggle for existence, with its enormous ratio of elimination in all species. To this we mustadd a fourth factor, the _intensification_ of variations which Darwinestablished as a fact, and which we are now able to account fortheoretically on the basis of germinal selection. It may be objectedthat there is considerable uncertainty about this _logical_ proof, because of our inability to demonstrate the selection-value of theinitial stages and the individual stages of increase. We havetherefore to fall back on _presumptive evidence_. This is to be foundin _the interpretative value of the theory_. Let us consider thispoint in greater detail. 

In the first place it is necessary to emphasize what is oftenoverlooked, namely, that the theory not only explains the_transformations_ of species, it also explains _their remaining thesame_; in addition to the principle of varying, it contains withinitself that of _persisting_. It is part of the essence of selection, that it not only causes a part to _vary_ till it has reached itshighest pitch of adaptation, but that it _maintains it at this pitch. This conserving influence of natural selection_ is of greatimportance, and was early recognised by Darwin; it follows naturallyfrom the principle of the survival of the fittest. 

We understand from this how it is that a species which has becomefully adapted to certain conditions of life ceases to vary, butremains "constant, " as long as the conditions of life _for_ it remainunchanged, whether this be for thousands of years, or for wholegeological epochs. But the most convincing proof of the power of theprinciple of selection lies in the innumerable multitude of phenomenawhich cannot be explained in any other way. To this category belongall structures which are only _passively_ of advantage to theorganism, because none of these can have arisen by the alleged_Lamarckian principle_. These have been so often discussed that weneed do no more than indicate them here. Until quite recently thesympathetic coloration of animals--for instance, the whiteness ofArctic animals--was referred, at least in part, to the _direct_influence of external factors, but the facts can best be explained byreferring them to the processes of selection, for then it isunnecessary to make the gratuitous assumption that many species aresensitive to the stimulus of cold and that others are not. The greatmajority of Arctic land-animals, mammals and birds, are white, andthis proves that they were all able to present the variation which wasmost useful for them. The sable is brown, but it lives in trees, wherethe brown colouring protects and conceals it more effectively. Themusk-sheep (_Ovibos moschatus_) is also brown, and contrasts sharplywith the ice and snow, but it is protected from beasts of prey by itsgregarious habit, and therefore it is of advantage to be visible fromas great a distance as possible. That so many species have been ableto give rise to white varieties does not depend on a specialsensitiveness of the skin to the influence of cold, but to the factthat Mammals and Birds have a general tendency to vary towards white. Even with us, many birds--starlings, blackbirds, swallows, etc. --occasionally produce white individuals, but the white varietydoes not persist, because it readily falls a victim to the carnivores. This is true of white fawns, foxes, deer, etc. The whiteness, therefore, arises from internal causes, and only persists when it isuseful. A great many animals living in a _green environment_ havebecome clothed in green, especially insects, caterpillars, andMantidae, both persecuted and persecutors. 

That it is not the direct effect of the environment which calls forththe green colour is shown by the many kinds of caterpillar which reston leaves and feed on them, but are nevertheless brown. These feed bynight and betake themselves through the day to the trunk of the tree, and hide in the furrows of the bark. We cannot, however, concludefrom this that they were _unable_ to vary towards green, for there areArctic animals which are white only in winter and brown in summer(Alpine hare, and the ptarmigan of the Alps), and there are also greenleaf-insects which remain green only while they are young anddifficult to see on the leaf, but which become brown again in the laststage of larval life, when they have outgrown the leaf. They thenconceal themselves by day, sometimes only among withered leaves on theground, sometimes in the earth itself. It is interesting that in onegenus, Chaerocampa, one species is brown in the last stage of larvallife, another becomes brown earlier, and in many species the laststage is not wholly brown, a part remaining green. Whether this is acase of a double adaptation, or whether the green is being graduallycrowded out by the brown, the fact remains that the same species, eventhe same individual, can exhibit both variations. The case is the samewith many of the leaf-like Orthoptera, as, for instance, the prayingmantis (_Mantis religiosa_) which we have already mentioned. 

But the best proofs are furnished by those of ten-cited cases in whichthe insect bears a deceptive resemblance to another object. We nowknow many such cases, such as the numerous imitations of green orwithered leaves, which are brought about in the most diverse ways, sometimes by mere variations in the form of the insect and in itscolour, sometimes by an elaborate marking, like that which occurs inthe Indian leaf-butterflies, _Kallima inachis_. In the singlebutterfly-genus Anaea, in the woods of South America, there are abouta hundred species which are all gaily coloured on the upper surface, and on the reverse side exhibit the most delicate imitation of thecolouring and pattern of a leaf, generally without any indication ofthe leaf-ribs, but extremely deceptive nevertheless. Anyone who hasseen only one such butterfly may doubt whether many of theinsignificant details of the marking can really be of advantage to theinsect. Such details are for instance the apparent holes and splitsin the apparently dry or half-rotten leaf, which are usually due tothe fact that the scales are absent on a circular or oval patch sothat the colourless wing-membrane lies bare, and one can look throughthe spot as through a window. Whether the bird which is seeking orpursuing the butterflies takes these holes for dewdrops, or for thework of a devouring insect, does not affect the question; themirror-like spot undoubtedly increases the general deceptiveness, forthe same thing occurs in many leaf-butterflies, though not in all, andin some cases it is replaced in quite a peculiar manner. In onespecies of Anaea (_A. Divina_), the resting butterfly looks exactlylike a leaf out of the outer edge of which a large semi-circular piecehas been eaten, possibly by a caterpillar; but if we look more closelyit is obvious that there is no part of the wing absent, and that thesemi-circular piece is of a clear, pale yellow colour, while the restof the wing is of a strongly contrasted dark brown. 

But the deceptive resemblance may be caused in quite a differentmanner. I have often speculated as to what advantage the brilliantwhite C could give to the otherwise dusky-coloured "Comma butterfly"(_Grapta C. Album_). Poulton's recent observations[46] have shown thatthis represents the imitation of a crack such as is often seen in dryleaves, and is very conspicuous because the light shines through it. 

The utility obviously lies in presenting to the bird the very familiarpicture of a broken leaf with a clear shining slit, and we mayconclude, from the imitation of such small details, that the birds arevery sharp observers and that the smallest deviation from the usualarrests their attention and incites them to closer investigation. Itis obvious that such detailed--we might almost say suchsubtle--deceptive resemblances could only have come about in thecourse of long ages through the acquirement from time to time ofsomething new which heightened the already existing resemblance. 

In face of facts like these there can be no question of chance and noone has succeeded so far in finding any other explanation to replacethat by selection. For the rest, the apparent leaves are by no meansperfect copies of a leaf; many of them only represent the torn orbroken piece, or the half or two-thirds of a leaf, but then the leavesthemselves frequently do not present themselves to the eye as a whole, but partially concealed among other leaves. Even those butterflieswhich, like the species of Kallima and Anaea, represent the whole of aleaf with stalk, ribs, apex, and the whole breadth, are not actualcopies which would satisfy a botanist; there is often much wanting. InKallima the lateral ribs of the leaf are never all included in themarkings; there are only two or three on the left side and at morefour or five on the right, and in many individuals these are ratherobscure, while in others they are comparatively distinct. Thisfurnishes us with fresh evidence in favour of their origin throughprocesses of selection, for a botanically perfect picture could notarise in this way; there could only be a fixing of such details asheightened the deceptive resemblance. 

Our postulate of origin through selection also enables us tounderstand why the leaf-imitation is on the lower surface of the wingin the diurnal Lepidoptera, and on the upper surface in the nocturnalforms, corresponding to the attitude of the wings in the restingposition of the two groups. 

The strongest of all proofs of the theory, however, is afforded bycases of true "mimicry, " those adaptations discovered by Bates in1861, consisting in the imitation of one species by another, whichbecomes more and more like its model. The model is always a speciesthat enjoys some special protection from enemies, whether because itis unpleasant to taste, or because it is in some way dangerous. 

It is chiefly among insects and especially among butterflies that wefind the greatest number of such cases. Several of these have beenminutely studied and every detail has been investigated so that it isdifficult to understand how there can still be disbelief in regard tothem. If the many and exact observations which have been carefullycollected and critically discussed for instance by Poulton[47] werethoroughly studied the arguments which are still frequently urgedagainst mimicry would be found untenable; we can hardly hope to findmore convincing proof of the actuality of the processes of selectionthan these cases put into our hands. The preliminary postulates of thetheory of mimicry have been disputed, for instance, that diurnalbutterflies are persecuted and eaten by birds, but observationsspecially directed towards this point in India, Africa, America andEurope have placed it beyond all doubt. If it were necessary I couldmyself furnish an account of my own observations on this point. 

In the same way it has been established by experiment and observationin the field that in all the great regions of distribution there arebutterflies which are rejected by birds and lizards, their chiefenemies, on account of their unpleasant smell or taste. Thesebutterflies are usually gaily and conspicuously coloured and thus--asWallace first interpreted it--are furnished with an easilyrecognisable sign: a sign of unpalatableness or _warning colours_. Ifthey were not thus recognisable easily and from a distance, they wouldfrequently be pecked at by birds, and then rejected because of theirunpleasant taste; but as it is, the insect-eaters recognise them atonce as unpalatable booty and ignore them. Such _immune_[48] species, wherever they occur, are imitated by other palatable species, whichthus acquire a certain degree of protection. 

It is true that this explanation of the bright, conspicuous coloursis only a hypothesis, but its foundations--unpalatableness, and theliability of other butterflies to be eaten, --are certain, and itsconsequences--the existence of mimetic palatable forms--conform it inthe most convincing manner. Of the many cases now known I select one, which is especially remarkable, and which has been thoroughlyinvestigated, _Papilla dardanus_ (_merope_), a large, beautiful, diurnal butterfly which ranges from Abyssinia throughout the whole ofAfrica to the south coast of Cape Colony. 

The males of this form are everywhere _almost_ the same in colour andin form of wings, save for a few variations in the sparse blackmarkings on the pale yellow ground. But the females occur in severalquite different forms and colourings, and one of these only, theAbyssinian form, is like the male, while the other three or four are_mimetic_, that is to say, they copy a butterfly of quite a differentfamily the Danaids, which are among the _immune_ forms. In each regionthe females have thus copied two or three different immune species. There is much that is interesting to be said in regard to thesespecies, but it would be out of keeping with the general tenor of thispaper to give details of this very complicated case of polymorphism in_P. Dardanus_. Anyone who is interested in the matter will find a fulland exact statement of the case in as far as we know it, in Poulton's_Essays on Evolution_ (pp. 373-375[49]). I need only add that threedifferent mimetic female forms have been reared from the eggs of asingle female in South Africa. The resemblance of the forms to theirimmune models goes so far that even the details of the _local_ formsof the models are copied by the mimetic species. 

It remains to be said that in Madagascar a butterfly, _Papilio meriones_, occurs, of which both sexes are very similar inform and markings to the non-mimetic male of _P. Dardanus_, so that itprobably represents the ancestor of this latter species. 

In face of such facts as these every attempt at another explanationmust fail. Similarly all the other details of the case fulfil thepreliminary postulates of selection, and leave no room for any otherinterpretation. That the males do not take on the protective colouringis easily explained, because they are in general more numerous, andthe females are more important for the preservation of the species, and must also live longer in order to deposit their eggs. We find thesame state of things in many other species, and in one case (_Elymniasundularis_) in which the male is also mimetically coloured, it copiesquite a differently coloured immune species from the model followed bythe female. This is quite intelligible when we consider that if therewere _too many_ false immune types, the birds would soon discover thatthere were palatable individuals among those with unpalatable warningcolours. Hence the imitation of different immune species by _Papiliodardanus_!

I regret that lack of space prevents my bringing forward more examplesof mimicry and discussing them fully. But from the case of _Papiliodardanus_ alone there is much to be learnt which is of the highestimportance for our understanding of transformations. It shows uschiefly what I once called, somewhat strongly perhaps, _theomnipotence of natural selection_ in answer to an opponent who hadspoken of its "inadequacy. " We here see that one and the same speciesis capable of producing four or five different patterns of colouringand marking; thus the colouring and marking are not, as has often beensupposed, a necessary outcome of the specific nature of the species, but a true adaptation, which cannot arise as a direct effect ofclimatic conditions, but solely through what I may call the sortingout of the variations produced by the species, according to theirutility. That caterpillars may be either green or brown is alreadysomething more than could have been expected according to the oldconception of species, but that one and the same butterfly should benow pale yellow, with black; now red with black and pure white; nowdeep black with large, pure white spots; and again black with a largeocheous-yellow spot, and many small white and yellow spots; that inone sub-species it may be tailed like the ancestral form, and inanother tailless like its Danaid model, --all this shows a far-reachingcapacity for variation and adaptation that we could never haveexpected if we did not see the facts before us. How it is possiblethat the primary colour-variations should thus be intensified andcombined remains a puzzle even now; we are reminded of the modernthree-colour printing, --perhaps similar combinations of the primarycolours take place in this case; in any case the direction of theseprimary variations is determined by the artist whom we know as naturalselection, for there is no other conceivable way in which the modelcould affect the butterfly that is becoming more and more like it. Thesame climate surrounds all four forms of female; they are subject tothe same conditions of nutrition. Moreover, _Papilio dardanus_ is byno means the only species of butterfly which exhibits different kindsof colour-pattern on its wings. Many species of the Asiatic genusElymnias have on the upper surface a very good imitation of an immuneEuploeine (Danainae), often with a steel-blue ground-colour, while theunder surface is well concealed when the butterfly is at rest, --thusthere are two kinds of protective coloration each with a differentmeaning! The same thing may be observed in many non-mimeticbutterflies, for instance in all our species of Vanessa, in which theunder side shows a grey-brown or brownish-black protective coloration, but we do not yet know with certainty what may be the biologicalsignificance of the gaily coloured upper surface. 

In general it may be said that mimetic butterflies are comparativelyrare species, but there are exceptions, for instance _Limenitisarchippus_ in North America, of which the immune model (_Danaidaplexippus_) also occurs in enormous numbers. 

In another mimicry-category the imitators are often more numerous thanthe models, namely in the case of the imitation of _dangerous insects_by harmless species. Bees and wasps are dreaded for their sting, andthey are copied by harmless flies of the genera Eristalis and Syrphus, and these mimics often occur in swarms about flowering plants withoutdamage to themselves or to their models; they are feared and aretherefore left unmolested. 

In regard also to the _faithfulness of the copy_ the facts are quitein harmony with the theory, according to which the resemblance musthave arisen and increased _by degrees_. We can recognise this in manycases, for even now the mimetic species show very _varying degrees ofresemblance_ to their immune model. If we compare, for instance, themany different imitators of _Danaida chrysippus_ we find that, withtheir brownish-yellow ground-colour, and the position and size, andmore or less sharp limitation of their clear marginal spots, they havereached very different degrees of nearness to their model. Or comparethe female of _Elymnias undularis_ with its model _Danaida genutia_;there is a general resemblance, but the marking of the Danaida is veryroughly imitated in Elymnias. 

Another fact that bears out the theory of mimicry is, that even whenthe resemblance in colour-pattern is very great, the _wing-venation_, which is so constant, and so important in determining the systematicposition of butterflies, is never affected by the variation. Thepursuers of the butterfly have no time to trouble about entomologicalintricacies. 

I must not pass over a discovery of Poulton's which is of greattheoretical importance--that mimetic butterflies may reach the sameeffect by very different means. [50] Thus the glass-like transparencyof the wing of a certain Ithomiine (Methona) and its Pierine mimic(_Dismorphia orise_) depends on a diminution in the size of thescales; in the Danaine genus Itune it is due to the fewness of thescales and in a third imitator, a moth (_Castnia linus var. Heliconoides_) the glass-like appearance of the wing is due neither todiminution nor to absence of scales, but to their absolutecolourlessness and transparency, and to the fact that they standupright. In another moth mimic (Anthomyza) the arrangement of thetransparent scales is normal. Thus it is not some unknown externalinfluence that has brought about the transparency of the wing in thesefive forms, as has sometimes been supposed. Nor is it a hypothetical_internal_ evolutionary tendency, for all three vary in a differentmanner. The cause of this agreement can only lie in selection, whichpreserves and intensifies in each species the favourable variationsthat present themselves. The great faithfulness of the copy isastonishing in these cases, for it is not _the whole_ wing which istransparent; certain markings are black in colour, and these contrastsharply with the glass-like ground. It is obvious that the pursuers ofthese butterflies must be very sharp-sighted, for otherwise theagreement between the species could never have been pushed so far. Theless the enemies see and observe, the more defective must theimitation be, and if they had been blind, no visible resemblancebetween the species which required protection could ever have arisen. 

A seemingly irreconcilable contradiction to the mimicry theory ispresented in the following cases, which were known to Bates, who, however, never succeeded in bringing them into line with the principleof mimicry. 

In South America there are, as we have already said, many mimics ofthe immune Ithomiinae (or as Bates called them Heliconidae). Amongthese there occur not merely species which are edible, and thusrequire the protection of a disguise, but others which are rejected onaccount of their unpalatableness. How could the Ithomiine dress havedeveloped in their case, and of what use is it, since the specieswould in any case be immune? In Eastern Brazil, for instance, thereare four butterflies, which bear a most confusing resemblance to oneanother in colour, marking, and form of wing, and all four areunpalatable to birds. They belong to four different genera and threesub-families, and we have to inquire: Whence came this resemblance andwhat end does it serve? For a long time no satisfactory answer couldbe found, but Fritz Müller, [51] seventeen years after Bates, offered asolution to the riddle, when he pointed out that young birds could nothave an instinctive knowledge of the unpalatableness of theIthomiines, but must learn by experience which species were edible andwhich inedible. Thus each young bird must have tasted at least oneindividual of each inedible species and discovered its unpalatability, before it learnt to avoid, and thus to spare the species. But if thefour species resemble each other very closely the bird will regardthem all as of the same kind, and avoid them all. Thus there developeda process of selection which resulted in the survival of theIthomiine-like individuals, and in so great an increase of resemblancebetween the four species, that they are difficult to distinguish onefrom another even in a collection. The advantage for the four species, living side by side as they do e. G. In Bahia, lies in the fact thatonly one individual from the _mimicry-ring_ ("inedible association")need be tasted by a young bird, instead of at least four individuals, as would otherwise be the case. As the number of young birds is great, this makes a considerable difference in the ratio of elimination. Thefour Brazilian species are _Lycorea halia_ (Danainae), _Heliconiusnarcaea_ (_eucrate_) (Heliconinae), _Melinaea ethra_, and _Mechanitislysimnia_ (Ithomiinae). 

These interesting mimicry-rings (trusts), which have much significancefor the theory, have been the subject of numerous and carefulinvestigations, and at least their essential features are now fullyestablished. Müller took for granted, without making anyinvestigations, that young birds only learn by experience todistinguish between different kinds of victims. But Lloyd Morgan's[52]experiments with young birds proved that this is really the case, andat the same time furnished an additional argument against the_Lamarckian principle_. 

In addition to the mimicry-rings first observed in South America, others have been described from Tropical India by Moore, and byPoulton and Dixey from Africa, and we may expect to learn many moreinteresting facts in this connection. Here again the preliminarypostulates of the theory are satisfied. And how much more that wouldlead to the same conclusion might be added!

As in the case of mimicry many species have come to resemble oneanother through processes of selection, so we know whole classes ofphenomena in which plants and animals have become adapted to oneanother, and have thus been modified to a considerable degree. I referparticularly to the relation between flowers and insects. Darwin hasshown that the originally inconspicuous blossoms of the phanerogamswere transformed into flowers through the visits of insects, and that, conversely, several large orders of insects have been graduallymodified by their association with flowers, especially as regards theparts of their body actively concerned. Bees and butterflies inparticular have become what they are through their relation toflowers. In this case again all that is apparently contradictory tothe theory can, on closer investigation, be beautifully interpreted incorroboration of it. Selection can give rise only to what is of use tothe organism actually concerned, never to what is of use to some otherorganism, and we must therefore expect to find that in flowers onlycharacters of use to _themselves_ have arisen, never characters whichare of use to insects only, and conversely that in the insectscharacters useful to them and not merely to the plants would haveoriginated. For a long time it seemed as if an exception to this ruleexisted in the case of the fertilisation of the yucca blossoms by alittle moth, _Pronuba yuccasella_. This little moth has asickle-shaped appendage to its mouth-parts which occurs hi no otherLepidopteron, and which is used for pushing the yellow pollen into theopening of the pistil, thus fertilising the flower. Thus it appears asif a new structure, which is useful only to the plant, has arisen inthe insect. But the difficulty is solved as soon as we learn that themoth lays its eggs in the fruit-buds of the Yucca, and that thelarvae, when they emerge, feed on the developing seeds. In effectingthe fertilisation of the flower the moth is at the same time makingprovision for its own offspring, since it is only after fertilisationthat the seeds begin to develop. There is thus nothing to prevent ourreferring this structural adaptation in _Pronuba yuccasella_ toprocesses of selection, which have gradually transformed the maxillarypalps of the female into the sickle-shaped instrument for collectingthe pollen, and which have at the same time developed in the insectthe instinct to press the pollen into the pistil. 

In this domain, then, the theory of selection finds nothing butcorroboration, and it would be impossible to substitute for it anyother explanation, which now that the facts are so well known, couldbe regarded as a serious rival to it. That selection is a factor, anda very powerful factor in the evolution of organisms, can no longer bedoubted. Even although we cannot bring forward formal proofs of it _indetail_, cannot calculate definitely the size of the variations whichpresent themselves, and their selection-value, cannot, in short, reduce the whole process to a mathematical formula, yet we must assumeselection, because it is the only possible explanation applicable towhole classes of phenomena, and because, on the other hand, it is madeup of factors which we know can be proved actually to exist, andwhich, _if_ they exist, must of logical necessity coöperate in themanner required by the theory. _We must accept it because thephenomena of evolution and adaptation must have a natural basis, andbecause it is the only possible explanation of them. _[53]

Many people are willing to admit that selection explains adaptations, but they maintain that only a part of the phenomena are thusexplained, because everything does not depend upon adaptation. Theyregard adaptation as, so to speak, a special effort on the part ofNature, which she keeps in readiness to meet particularly difficultclaims of the external world on organisms. But if we look at thematter more carefully we shall find that adaptations are by no meansexceptional, but that they are present everywhere in such enormousnumbers, that it would be difficult in regard to any structurewhatever, to prove that adaptation had _not_ played a part in itsevolution. 

How often has the senseless objection been urged against selectionthat it can create nothing, it can only reject. It is true that itcannot create either the living substance or the variations of it;both must be given. But in rejecting one thing it preserves another, intensifies it, combines it, and in this way _creates_ what is new. _Everything_ in organisms depends on adaptation; that is to say, everything must be admitted through the narrow door of selection, otherwise it can take no part in the building up of the whole. But, itis asked, what of the direct effect of external conditions, temperature, nutrition, climate and the like? Undoubtedly these cangive rise to variations, but they too must pass through the door ofselection, and if they cannot do this they are rejected, eliminatedfrom the constitution of the species. 

It may, perhaps, be objected that such external influences are oftenof a compelling power, and that every animal must submit to them, andthat thus selection has no choice and can neither select nor reject. There may be such cases; let us assume for instance that the effectof the cold of the Arctic regions was to make all the mammals becomeblack; the result would be that they would all be eliminated byselection, and that no mammals would be able to live there at all. Butin most cases a certain percentage of animals resists these stronginfluences, and thus selection secures a foothold on which to work, eliminating the unfavourable variation, and establishing a usefulcolouring, consistent with what is required for the maintenance of thespecies. 

Everything depends upon adaptation! We have spoken much of adaptationin colouring, in connection with the examples brought into prominenceby Darwin, because these are conspicuous, easily verified, and at thesame time convincing for the theory of selection. But is it onlydesert and polar animals whose colouring is determined throughadaptation? Or the leaf-butterflies, and the mimetic species, or theterrifying markings, and "warning-colours" and a thousand other kindsof sympathetic colouring? It is, indeed, never the colouring alonewhich makes up the adaptation; the structure of the animal plays apart, often a very essential part, in the protective disguise, andthus _many_ variations may cooperate towards _one_ common end. And itis to be noted that it is by no means only external parts that arechanged; internal parts are _always_ modified at the same time--forinstance, the delicate elements of the nervous system on which dependthe _instinct_ of the insect to hold its wings, when at rest, in aperfectly definite position, which, in the leaf-butterfly, has theeffect of bringing the two pieces on which the marking occurs on theanterior and posterior wing into the same direction, and thusdisplaying as a whole the fine curve of the midrib on the seemingleaf. But the wing-holding instinct is not regulated in the same wayin all leaf-butterflies; even our indigenous species of Vanessa, withtheir protective ground-colouring, have quite a distinctive way ofholding their wings so that the greater part of the anterior wing iscovered by the posterior when the butterfly is at rest. But theprotective colouring appears on the posterior wing and on the tip ofthe anterior, _to precisely the distance to which it is leftuncovered_. This occurs, as Standfuss has shown, in different degreesin our two most nearly allied species, the uncovered portion beingsmaller in _V. Urticae_ than in _V. Polychloros_. In this case, as inmost leaf-butterflies, the holding of the wing was probably theprimary character; only after that was thoroughly established did theprotective marking develop. In any case, the instinctive manner ofholding the wings is associated with the protective colouring, andmust remain as it is if the latter is to be effective. How greatlyinstincts may change, that is to say, may be adapted, is shown by thecase of the Noctuid "shark" moth, _Xylina vetusta_. This form bears amost deceptive resemblance to a piece of rotten wood, and theappearance is greatly increased by the modification of the innateimpulse to flight common to so many animals, which has here beentransformed into an almost contrary instinct. This moth does not flyaway from danger, but "feigns death, " that is, it draws antennae, legsand wings close to the body, and remains perfectly motionless. It maybe touched, picked up, and thrown down again, and still it does notmove. This remarkable instinct must surely have developedsimultaneously with the wood-colouring; at all events, bothcoöperating variations are now present, and prove that both theexternal and the most minute internal structure have undergone aprocess of adaptation. 

The case is the same with all structural variations of animal parts, which are not absolutely insignificant. When the insects acquiredwings they must also have acquired the mechanism with which to movethem--the musculature, and the nervous apparatus necessary for itsautomatic regulation. All instincts depend upon compound reflexmechanisms and are just as indispensable as the parts they have to setin motion, and all may have arisen through processes of selection ifthe reasons which I have elsewhere given for this view arecorrect. [54]

Thus there is no lack of adaptations within the organism, andparticularly in its most important and complicated parts, so that wemay say that there is no actively functional organ that has notundergone a process of adaptation relative to its function and therequirements of the organism. Not only is every gland structurallyadapted, down to the very minutest histological details, to itsfunction, but the function is equally minutely adapted to the needs ofthe body. Every cell in the mucous lining of the intestine is exactlyregulated in its relation to the different nutritive substances, andbehaves in quite a different way towards the fats, and towardsnitrogenous substances, or peptones. 

I have elsewhere called attention to the many adaptations of the whaleto the surrounding medium, and have pointed out--what has long beenknown, but is not universally admitted, even now--that in it a greatnumber of important organs have been transformed in adaptation to thepeculiar conditions of aquatic life, although the ancestors of thewhale must have lived, like other hair-covered mammals, on land. Icited a number of these transformations--the fish-like form of thebody, the hairlessness of the skin, the transformation of thefore-limbs to fins, the disappearance of the hind-limbs and thedevelopment of a tail fin, the layer of blubber under the skin, whichaffords the protection from cold necessary to a warm-blooded animal, the disappearance of the ear-muscles and the auditory passages, thedisplacement of the external nares to the forehead for the greatersecurity of the breathing-hole during the brief appearance at thesurface, and certain remarkable changes in the respiratory andcirculatory organs which enable the animal to remain for a long timeunder water. I might have added many more, for the list of adaptationsin the whale to aquatic life is by no means exhausted; they are foundin the histological structure and in the minutest combinations in thenervous system. For it is obvious that a tail-fin must be used inquite a different way from a tail, which serves as a fly-brush inhoofed animals, or as an aid to springing in the kangaroo or as aclimbing organ; it will require quite different reflex-mechanisms andnerve combinations in the motor centres. 

I used this example in order to show how unnecessary it is to assume aspecial internal evolutionary power for the phylogenesis of species, for this whole order of whales is, so to speak, _made up ofadaptations_; it deviates in many essential respects from the usualmammalian type, and all the deviations are adaptations to aquaticlife. But if precisely the most essential features of the organisationthus depend upon adaptation, what is left for a phyletic force to do, since it is these essential features of the structure it would have todetermine? There are few people now who believe in a phyleticevolutionary power, which is not made up of the forces known tous--adaptation and heredity--but the conviction that _every_ part ofan organism depends upon adaptation has not yet gained a firm footing. Nevertheless, I must continue to regard this conception as the correctone, as I have long done. 

I may be permitted one more example. The feather of a bird is amarvellous structure, and no one will deny that as a whole it dependsupon adaptation. But what part of it _does not_ depend uponadaptation? The hollow quill, the shaft with its hard, thin, lightcortex, and the spongy substance within it, its square sectioncompared with the round section of the quill, the flat barbs, theirshort, hooked barbules which, in the flight-feathers, hook into oneanother with just sufficient firmness to resist the pressure of theair at each wing-beat, the lightness and firmness of the wholeapparatus, the elasticity of the vane, and so on. And yet all thisbelongs to an organ which is only passively functional, and thereforecan have nothing to do with the _Lamarckian principle_. Nor can thefeather have arisen through some magical effect of temperature, moisture, electricity, or specific nutrition, and thus selection isagain our only anchor of safety. 

But--it will be objected--the substance of which the feather consists, this peculiar kind of horny substance, did not first arise throughselection in the course of the evolution of the birds, for it formedthe covering of the scales of their reptilian ancestors. It is quitetrue that a similar substance covered the scales of the Reptiles, butwhy should it not have arisen among them through selection? Or in whatother way could it have arisen, since scales are also passively usefulparts? It is true that if we are only to call adaptation what has beenacquired by the species we happen to be considering, there wouldremain a great deal that could not be referred to selection; but weare postulating an evolution which has stretched back through aeons, and in the course of which innumerable adaptations took place, whichhad not merely ephemeral persistence in a genus, a family or a class, but which was continued into whole Phyla of animals, with continualfresh adaptations to the special conditions of each species, family, or class, yet with persistence of the fundamental elements. Thus thefeather, once acquired, persisted in all birds, and the vertebralcolumn, once gained by adaptation in the lowest forms, has persistedin all the Vertebrates from Amphioxus upwards, although with constantreadaptation to the conditions of each particular group. Thuseverything we can see in animals is adaptation, whether of to-day, orof yesterday, or of ages long gone by; every kind of cell, whetherglandular, muscular, nervous, epidermic, or skeletal, is adapted toabsolutely definite and specific functions, and every organ which iscomposed of these different kinds of cells contains them in the properproportions, and in the particular arrangement which best serves thefunction of the organ; it is thus adapted to its function. 

All parts of the organism are tuned to one another, that is, _they areadapted to one another_, and in the same way _the organism as a wholeis adapted to the conditions of its life, and it is so at every stageof its evolution. _

But all adaptations _can_ be referred to selection; the only pointthat remains doubtful is whether they all _must_ be referred to it. 

However that may be, whether the _Lamarckian principle_ is a factorthat has coöperated with selection in evolution, or whether it isaltogether fallacious, the fact remains, that selection is the causeof a great part of the phyletic evolution of organisms on our earth. Those who agree with me in rejecting the _Lamarckian principle_ willregard selection as the only _guiding_ factor in evolution, whichcreates what is new out of the transmissible variations, by orderingand arranging these, selecting them in relation to their number andsize, as the architect does his building-stones so that a particularstyle must result. [55] But the building-stones themselves, thevariations, have their basis in the influences which cause variationin those vital units which are handed on from one generation toanother, whether, taken together they form the _whole_ organism, as inBacteria and other low forms of life, or only a germ-substance, as inunicellular and multicellular organisms. 

FOOTNOTES:

[Footnote 33: _Vorträge über Descendenztheorie_, Jena, 1904, II. 269. Eng. Transl. London, 1904, II. P. 317. ]

[Footnote 34: See Poulton, _Essays on Evolution_, Oxford, 1908. Pp. Xix-xxii. ]

[Footnote 35: _Origin of Species_ (6th edit), pp. 176 _et seq. _]

[Footnote 36: Chun, _Reise der Valdivia_, Leipzig, 1904. ]

[Footnote 37: Plate, _Selektionsprinzip u. Probleme der Artbildung_(3rd edit. ), Leipzig, 1908. ]

[Footnote 38: _Studien zur Descendenz-Theorie_ II. , "Die Enstehung derZeichnung bei den Schmetterlings-raupen, " Leipzig, 1876. ]

[Footnote 39: _Origin of Species_ (6th edit. ), p. 232. ]

[Footnote 40: _Origin of Species_, p. 233; see also edit. 1, p. 242. ]

[Footnote 41: _Ibid. _ p. 230. ]

[Footnote 42: _The Effect of External Influences upon Development_, Romanes Lecture, Oxford, 1894. ]

[Footnote 43: See Poulton, _Essays on Evolution_, 1908, pp. 316, 317. ]

[Footnote 44: _The Evolution Theory_, London, 1904, I. P. 219. ]

[Footnote 45: _Report of the British Association_ (Bristol, 1898), London, 1899, pp. 906-909. ]

[Footnote 46: _Proc. Ent. Soc. _, London, May 6, 1903. ]

[Footnote 47: _Essays on Evolution_, 1889-1907, Oxford, 1908, _passim_, e. G. P. 269. ]

[Footnote 48: The expression does not refer to all the enemies of thisbutterfly; against ichneumon-flies, for instance, their unpleasantsmell usually gives no protection. ]

[Footnote 49: Professor Poulton has corrected some wrong descriptionswhich I had unfortunately overlooked in the Plates of my book_Vorträge über Descendenztheorie_, and which refer to _Papiliodardanus_ (_merope_). These mistakes are of no importance as far as anunderstanding of the mimicry-theory is concerned, but I hope shortlyto be able to correct them in a later edition. ]

[Footnote 50: _Journ. Linn. Soc. London_ (_Zool. _), Vol. Xxvi. 1898, pp. 598-602. ]

[Footnote 51: In _Kosmos_, 1879, p. 100. ]

[Footnote 52: _Habit and Instinct_, London. 1896. ]

[Footnote 53: This has been discussed in many of my earlier works. Seefor instance _The All-Sufficiency of Natural Selection, a reply toHerbert Spencer_, London, 1893. ]

[Footnote 54: _The Evolution Theory_, London, 1904, p. 144. ]

[Footnote 55: _Variation under Domestication_, 1875, II. Pp. 426, 427. ]

III

HEREDITY AND VARIATION IN MODERN LIGHTS

BY W. BATESON, M. A. , F. R. S. 

_Professor of Biology in the University of Cambridge_

Darwin's work has the property of greatness in that it may be admiredfrom more aspects than one. For some the perception of the principleof Natural Selection stands out as his most wonderful achievement towhich all the rest is subordinate. Others, among whom I would rangemyself, look up to him rather as the first who plainly distinguished, collected, and comprehensively studied that new class of evidence fromwhich hereafter a true understanding of the process of Evolution maybe developed. We each prefer our own standpoint of admiration; but Ithink that it will be in their wider aspect that his labours will mostcommand the veneration of posterity. 

A treatise written to advance knowledge may be read in two moods. Thereader may keep his mind passive, willing merely to receive theimpress of the writer's thought; or he may read with his attentionstrained and alert, asking at every instant how the new knowledge canbe used in a further advance, watching continually for fresh footholdsby which to climb higher still. Of Shelley it has been said that hewas a poet for poets: so Darwin was a naturalist for naturalists. Itis when his writings are used in the critical and more exacting spiritwith which we test the outfit for our own enterprise that we learntheir full value and strength. Whether we glance back and compare hisperformance with the efforts of his predecessors, or look forwardalong the course which modern research is disclosing, we shall honourmost in him not the rounded merit of finite accomplishment, but thecreative power by which he inaugurated a line of discovery endless invariety and extension. Let us attempt thus to see his work in trueperspective between the past from which it grew, and the present whichis its consequence. Darwin attacked the problem of Evolution byreference to facts of three classes: Variation; Heredity; NaturalSelection. His work was not as the laity suppose, a sudden andunheralded revelation, but the first fruit of a long and hithertobarren controversy. The occurrence of variation from type, and thehereditary transmission of such variation had of course been longfamiliar to practical men, and inferences as to the possible bearingof those phenomena on the nature of specific difference had been fromtime to time drawn by naturalists. Maupertuis, for example, wrote: "Cequi nous reste à examiner, c'est comment d'un seul individu, il a punaître tant d'espèces si différentes. " And again: "La Nature contientle fonds de toutes ces variétés: mais le hasard ou l'art les mettenten œuvre. C'est ainsi que ceux dont l'industrie s'applique àsatisfaire le goût des curieux, sont, pour ainsi dire, créateursd'espèces nouvelles. "[56]

Such passages, of which many (though few so emphatic) can be found ineighteenth century writers, indicate a true perception of the mode ofEvolution. The speculations hinted at by Buffon, [57] developed byErasmus Darwin, and independently proclaimed above all by Lamarck, gave to the doctrine of descent a wide renown. The uniformitarianteaching which Lyell deduced from geological observation had gainedacceptance. The facts of geographical distribution[58] had been shownto be obviously inconsistent with the Mosaic legend. Prichard, andLawrence, following the example of Blumenbach, had successfullydemonstrated that the races of Man could be regarded as differentforms of one species, contrary to the opinion up till then received. These treatises all begin, it is true, with a profound obeisance tothe sons of Noah, but that performed, they continue on strictly modernlines. The question of the mutability of species was thus prominentlyraised. 

Those who rate Lamarck no higher than did Huxley in his contemptuousphrase "_buccinator tantum_, " will scarcely deny that the sound of thetrumpet had carried far, or that its note was clear. If then therewere few who had already turned to evolution with positive conviction, all scientific men must at least have known that such views had beenpromulgated; and many must, as Huxley says, have taken up his ownposition of "critical expectancy. "[59]

Why, then, was it, that Darwin succeeded where the rest had failed?The cause of that success was twofold. First, and obviously, in theprinciple of Natural Selection he had a suggestion which would work. It might not go the whole way, but it was true as far as it went. Evolution could thus in great measure be fairly represented as aconsequence of demonstrable processes. Darwin seldom endangers themechanism he devised by putting on it strains much greater than it canbear. He at least was under no illusion as to the omnipotence ofSelection; and he introduces none of the forced pleading which inrecent years has threatened to discredit that principle. 

For example, in the latest text of the _Origin_[60] we find himsaying:

 "But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position--namely, at the close of the Introduction--the following words: 'I am convinced that natural selection has been the main but not the exclusive means of modification. '"

But apart from the invention of this reasonable hypothesis, which maywell, as Huxley estimated, "be the guide of biological andpsychological speculation for the next three or four generations, "Darwin made a more significant and imperishable contribution. Not fora few generations, but through all ages he should be remembered as thefirst who showed clearly that the problems of Heredity and Variationare soluble by observation, and laid down the course by which we mustproceed to their solution. [61] The moment of inspiration did not comewith the reading of Malthus, but with the opening of the "firstnote-book on Transmutation of Species. "[62] Evolution is a process ofVariation and Heredity. The older writers, though they had some vagueidea that it must be so, did not study Variation and Heredity. Darwindid, and so begat not a theory, but a science. 

The extent to which this is true, the scientific world is onlybeginning to realise. So little was the fact appreciated in Darwin'sown time that the success of his writings was followed by an almosttotal cessation of work in that special field. Of the causes which ledto these remarkable consequences I have spoken elsewhere. Theyproceeded from circumstances peculiar to the time; but whatever thecauses there is no doubt that this statement of the result ishistorically exact, and those who make it their business to collectfacts elucidating the physiology of Heredity and Variation are wellaware that they will find little to reward their quest in the leadingscientific Journals of the Darwinian epoch. 

In those thirty years the original stock of evidence current and incirculation even underwent a process of attrition. As in the story ofthe Eastern sage who first wrote the collected learning of theuniverse for his sons in a thousand volumes and by successivecompression and burning reduced them to one and from this by furtherburning distilled the single ejaculation of the Faith "There is no godbut God and Mohammed is the Prophet of God, " which was all his maturerwisdom deemed essential:--so in the books of that period do we findthe _corpus_ of genetic knowledge dwindle to a few prerogativeinstances and these at last to the brief formula of an unquestionedcreed. 

And yet in all else that concerns biological science this period was, in very truth, our Golden Age, when the natural history of the earthwas explored as never before; morphology and embryology wereexhaustively ransacked; the physiology of plants and animals began torival chemistry and physics in precision of method and in the rapidityof its advances; and the foundations of pathology were laid. 

In contrast with this immense activity elsewhere the neglect whichbefel the special physiology of Descent, or Genetics as we now callit, is astonishing. This may of course be interpreted as meaning thatthe favoured studies seemed to promise a quicker return for effort, but it would be more true to say that those who chose these otherpursuits did so without making any such comparison; for the idea thatthe physiology of Heredity and Variation was a coherent science, offering possibilities of extraordinary discovery, was not present totheir minds at all. In a word, the existence of such a science waswell nigh forgotten. It is true that in ancillary periodicals, as forexample those that treat of entomology or horticulture, or in thewritings of the already isolated systematists, [63] observations withthis special bearing were from time to time related, but the class offact on which Darwin built his conceptions of Heredity and Variationwas not seen in the highways of biology. It formed no part of theofficial curriculum of biological students, and found no place amongthe subjects which their teachers were investigating. 

During this period nevertheless one distinct advance was made, thatwith which Weismann's name is prominently connected. In Darwin'sgenetic scheme the hereditary transmission of parental experience andits consequences played a considerable role. Exactly how great thatrole was supposed to be, he with his habitual caution refrained fromspecifying, for the sufficient reason that he did not know. Nevertheless much of the process of Evolution, especially that bywhich organs have become degenerate and rudimentary, was certainlyattributed by Darwin to such inheritance, though since belief in theinheritance of acquired characters fell into dispute, the fact hasbeen a good deal overlooked. The _Origin_ without "use and disuse"would be a materially different book. A certain vacillation isdiscernible in Darwin's utterances on this question, and the fact gaveto the astute Butler an opportunity for his most telling attack. Thediscussion which best illustrates the genetic views of the periodarose in regard to the production of the rudimentary condition of thewings of many beetles in the Madeira group of islands, and bycomparing passages from the _Origin_[64] Butler convicts Darwin ofsaying first that this condition was in the main the result ofSelection, with disuse aiding, and in another place that the maincause of degeneration was disuse, but that Selection had aided. ToDarwin however I think the point would have seemed one of dialeticsmerely. To him the one paramount purpose was to show that somehow anEvolution by means of Variation and Heredity might have brought aboutthe facts observed, and whether they had come to pass in the one wayor the other was a matter of subordinate concern. 

To us moderns the question at issue has a diminished significance. Forover all such debates a change has been brought by Weismann'schallenge for evidence that use and disuse have any transmittedeffects at all. Hitherto the transmission of many acquiredcharacteristics had seemed to most naturalists so obvious as not tocall for demonstration. [65] Weismann's demand for facts in support ofthe main proposition revealed at once that none having real cogencycould be produced. The time-honoured examples were easily shown to becapable of different explanations. A few certainly remain which cannotbe so summarily dismissed, but--though it is manifestly impossiblehere to do justice to such a subject--I think no one will dispute thatthese residual and doubtful phenomena, whatever be their true nature, are not of a kind to help us much in the interpretation of any ofthose complex cases of adaptation which on the hypothesis of unguidedNatural Selection are especially difficult to understand. Use anddisuse were invoked expressly to help us over these hard places; butwhatever changes can be induced in offspring by direct treatment ofthe parents, they are not of a kind to encourage hope of realassistance from that quarter. It is not to be denied that through thecollapse of this second line of argument the Selection hypothesis hashad to take an increased and perilous burden. Various ways of meetingthe difficulty have been proposed, but these mostly resolve themselvesinto improbable attempts to expand or magnify the powers of NaturalSelection. 

Weismann's interpellation, though negative in purpose, has had alasting and beneficial effect, for through his thorough demolition ofthe old loose and distracting notions of inherited experience, theground has been cleared for the construction of a true knowledge ofheredity based on experimental fact. 

In another way he made a contribution of a more positive character, for his elaborate speculations as to the genetic meaning ofcytological appearances have led to a minute investigation of thevisible phenomena occurring in those cell-divisions by whichgerm-cells arise. Though the particular views he advocated have verylargely proved incompatible with the observed facts of heredity, yetwe must acknowledge that it was chiefly through the stimulus ofWeismann's ideas that those advances in cytology were made; and thoughthe doctrine of the continuity of germ-plasm cannot be maintained inthe form originally propounded, it is in the main true andilluminating. [66] Nevertheless in the present state of knowledge weare still as a rule quite unable to connect cytological appearanceswith any genetic consequences and save in one respect (obviously ofextreme importance--to be spoken of later) the two sets of phenomenamight, for all we can see, be entirely distinct. 

I cannot avoid attaching importance to this want of connection betweenthe nuclear phenomena and the features of bodily organisation. Allattempts to investigate Heredity by cytological means lie under thedisadvantage that it is the nuclear changes which can alone beeffectively observed. Important as they must surely be, I have neverbeen persuaded that the rest of the cell counts for nothing. What weknow of the behaviour and variability of chromosomes seems in myopinion quite incompatible with the belief that they alone governform, and are the sole agents responsible in heredity. [67]

If, then, progress was to be made in Genetics, work of a differentkind was required. To learn the laws of Heredity and Variation thereis no other way than that which Darwin himself followed, the directexamination of the phenomena. A beginning could be made by collectingfortuitous observations of this class, which have often thrown asuggestive light, but such evidence can be at best but superficial andsome more penetrating instrument of research is required. This canonly be provided by actual experiments in breeding. 

The truth of these general considerations was becoming gradually clearto many of us when in 1900 Mendel's work was rediscovered. Segregation, a phenomenon of the utmost novelty, was thus revealed. From that moment not only in the problem of the origin of species, butin all the great problems of biology a new era began. So unexpectedwas the discovery that many naturalists were convinced it was untrue, and at once proclaimed Mendel's conclusions as either altogethermistaken, or if true, of very limited application. Many fantasticnotions about the workings of Heredity had been asserted as generalprinciples before: this was probably only another fancy of the sameclass. 

Nevertheless those who had a preliminary acquaintance with the factsof Variation were not wholly unprepared for some such revelation. Theessential deduction from the discovery of segregation was that thecharacters of living things are dependent on the presence of definiteelements or factors, which are treated as units in the processes ofHeredity. These factors can thus be recombined in various ways. Theyact sometimes separately, and sometimes they interact in conductionwith each other, producing their various effects. All this indicates adefiniteness and specific order in heredity, and therefore invariation. This order cannot by the nature of the case be dependent onNatural Selection for its existence, but must be a consequence of thefundamental chemical and physical nature of living things. The studyof Variation had from the first shown that an orderliness of this kindwas present. The bodies and the properties of livings things arecosmic, not chaotic. No matter how low in the scale we go, never do wefind the slightest hint of a diminution in that all-pervadingorderliness, nor can we conceive an organism existing for a moment inany other state. Moreover not only does this order prevail in normalforms, but again and again it is to be seen in newly-sprung varieties, which by general consent cannot have been subjected to a prolongedSelection. The discovery of Mendelian elements admirably coincidedwith and at once gave a rationale of these facts. Genetic Variation isthen primarily the consequence of additions to, or omissions from, thestock of elements which the species contains. The furtherinvestigation of the species-problem must thus proceed by theanalytical method which breeding experiments provide. 

In the nine years which have elapsed since Mendel's clue becamegenerally known, progress has been rapid. We now understand theprocess by which a polymorphic race maintains its polymorphism. When afamily consists of dissimilar members, given the numerical proportionsin which these members are occurring, we can represent theircomposition symbolically and state what types can be transmitted bythe various members. The difficulty of the "swamping effects ofinter-crossing" is practically at an end. Even the famous puzzle ofsex-limited inheritance is solved, at all events in its more regularmanifestations, and we know now how it is brought about that thenormal sisters of a colour-blind man can transmit the colour-blindnesswhile his normal brothers cannot transmit it. 

We are still only on the fringe of the inquiry. It can be seenextending and ramifying in many directions. To enumerate these herewould be impossible. A whole new range of possibilities is beingbrought into view by study of the inter-relations between the simplefactors. By following up the evidence as to segregation, indicationshave been obtained which can only be interpreted as meaning that whenmany factors are being simultaneously redistributed among thegerm-cells, certain of them exert what must be described as arepulsion upon other factors. We cannot surmise whither this discoverymay lead. 

In the new light all the old problems wear a fresh aspect. Upon thequestion of the nature of Sex, for example, the bearing of Mendelianevidence is close. Elsewhere I have shown that from several sets ofparallel experiments the conclusion is almost forced upon us that, inthe types investigated, of the two sexes the female is to be regardedas heterozygous in sex, containing one unpaired dominant element, while the male is similarly homozygous in the absence of thatelement. [68] It is not a little remarkable that on this point--whichis the only one where observations of the nuclear processes ofgameto-genesis have yet been brought into relation with the visiblecharacteristics of the organisms themselves--there should bediametrical opposition between the results of breeding experiments andthose derived from cytology. 

Those who have followed the researches of the American school will beaware that, after it had been found in certain insects that thespermatozoa were of two kinds according as they contained or did notcontain the accessory chromosome, E. B. Wilson succeeded in provingthat the sperms possessing this accessory body were destined to form_females_ on fertilisation, while sperms without it form males, theeggs being apparently indifferent. Perhaps the most striking of allthis series of observations is that lately made by T. H. Morgan, [69]since confirmed by von Baehr, that in a Phylloxeran two kinds ofspermatids are formed, respectively with and without an accessory (inthis case, _double_) chromosome. Of these, only those possessing theaccessory body become functional spermatozoa, the others degenerating. We have thus an elucidation of the puzzling fact that in these formsfertilisation results in the formation of _females_ only. How themales are formed--for of course males are eventually produced by theparthenogenetic females--we do not know. 

If the accessory body is really to be regarded as bearing the factorfor femaleness, then in Mendelian terms female is DD and male is DR. The eggs are indifferent and the spermatozoa are each male, _or_female. But according to the evidence derived from a study of thesex-limited descent of certain features in other animals theconclusion seems equally clear that in them female must be regarded asDR and male as RR. The eggs are thus each either male or female andthe spermatozoa are indifferent. How this contradictory evidence is tobe reconciled we do not yet know. The breeding work concerns fowls, canaries, and the Currant moth (_Abraxas grossulariata_). Theaccessory chromosome has been now observed in most of the greatdivisions of insects, [70] except, as it happens, Lepidoptera. At firstsight it seems difficult to suppose that a feature apparently sofundamental as sex should be differently constituted in differentanimals, but that seems at present the least improbable inference. Imention these two groups of facts as illustrating the nature andmethods of modern genetic work. We must proceed by minute and specificanalytical investigation. Wherever we look we find traces of theoperation of precise and specific rules. 

In the light of present knowledge it is evident that before we canattack the Species-problem with any hope of success there are vastarrears to be made up. He would be a bold man who would now assertthat there was no sense in which the term Species might not have astrict and concrete meaning in contradistinction to the term Variety. We have been taught to regard the difference between species andvariety as one of degree. I think it unlikely that this conclusionwill bear the test of further research. To Darwin the question, Whatis a variation? presented no difficulties. Any difference betweenparent and offspring was a variation. Now we have to be more precise. First we must, as de Vries has shown, distinguish real, genetic, variation from _fluctuational_ variations, due to environmental andother accidents, which cannot be transmitted. Having excluded thesesources of error the variations observed must be expressed in terms ofthe factors to which they are due before their significance can beunderstood. For example, numbers of the variations seen underdomestication, and not a few witnessed in nature, are simply theconsequence of some ingredient being in an unknown way omitted fromthe composition of the varying individual. The variation may on thecontrary be due to the addition of some new element, but to prove thatit is so is by no means an easy matter. Casual observation is useless, for though these latter variations will always be dominants, yet manydominant characteristics may arise from another cause, namely themeeting of complementary factors, and special study of each case intwo generations at least is needed before these two phenomena can bedistinguished. 

When such considerations are fully appreciated it will be realisedthat medleys of most dissimilar occurrences are all confused togetherunder the term Variation. One of the first objects of genetic analysisis to disentangle this mass of confusion. 

To those who have made no study of heredity it sometimes appears thatthe question of the effect of conditions in causing variation is onewhich we should immediately investigate, but a little thought willshow that before any critical inquiry into such possibilities can beattempted, a knowledge of the working of heredity under conditions asfar as possible uniform must be obtained. At the time when Darwin waswriting, if a plant brought into cultivation gave off an albinovariety, such an event was without hesitation ascribed to the changeof life. Now we see that albino _gametes_, germs, that is to say, which are destitute of the pigment-forming factor, may have beenoriginally produced by individuals standing an indefinite number ofgenerations back in the ancestry of the actual albino, and it isindeed almost certain that the variation to which the appearance ofthe albino is due cannot have taken place in a generation later thanthat of the grandparents. It is true that when a new _dominant_appears we should feel greater confidence that we were witnessing theoriginal variation, but such events are of extreme rarity, and no suchcase has come under the notice of an experimenter in modern times, asfar as I am aware. That they must have appeared is clear enough. Nothing corresponding to the Brown-breasted Game fowl is known wild, yet that colour is a most definite dominant, and at some moment since_Gallus bankiva_ was domesticated, the element on which that specialcolour depends must have at least once been formed in the germ-cell ofa fowl; but we need harder evidence than any which has yet beenproduced before we can declare that this novelty came throughover-feeding, or change of climate, or any other disturbanceconsequent on domestication. When we reflect on the intricacies ofgenetic problems as we must now conceive them there come moments whenwe feel almost thankful that the Mendelian principles were unknown toDarwin. The time called for a bold pronouncement, and he made it, toour lasting profit and delight. With fuller knowledge we pass oncemore into a period of cautious expectation and reserve. 

In every arduous enterprise it is pleasanter to look back atdifficulties overcome than forward to those which still seeminsurmountable, but in the next stage there is nothing to be stainedby disguising the fact that the attributes of living things are notwhat we used to suppose. If they are more complex in the sense thatthe properties they display are throughout so regular[71] that theSelection of minute random variations is an unacceptable account ofthe origin of their diversity, yet by virtue of that very regularitythe problem is limited in scope and thus simplified. 

To begin with, we must relegate Selection to its proper place. Selection permits the viable to continue and decides that thenon-viable shall perish; just as the temperature of our atmospheredecides that no liquid carbon shall be found on the face of the earth:but we do not suppose that the form of the diamond has been graduallyachieved by a process of Selection. So again, as the course of descentbranches in the successive generations, Selection determines alongwhich branch Evolution shall proceed, but it does not decide whatnovelties that branch shall bring forth. "_La Nature contient le fondsde toutes ces variétés, mais le hazard ou l'art les mettent enœuvre_, " as Maupertuis most truly said. 

Not till knowledge of the genetic properties of organisms has attainedto far greater completeness can evolutionary speculations have morethan a suggestive value. By genetic experiment, cytology andphysiological chemistry aiding, we may hope to acquire such knowledge. In 1872 Nathusius wrote:[72] "Das Gesetz der Vererbung ist noch nichterkannt; der Apfel ist noch nicht vom Baum der Erkenntniss gefallen, welcher, der Sage nach, Newton auf den rechten Weg zur Ergründung derGravitationsgesetze führte. " We cannot pretend that the words are notstill true, but in Mendelian analysis the seeds of that apple-tree atlast are sown. 

If we were asked what discovery would do most to forward our inquiry, what one bit of knowledge would more than any other illuminate theproblem, I think we may give the answer without hesitation. Thegreatest advance that we can foresee will be made when it is foundpossible to connect the geometrical phenomena of development with thechemical. The geometrical symmetry of living things is the key to aknowledge of their regularity, and the forces which cause it. In thesymmetry of the dividing cell the basis of that resemblance we callHeredity is contained. To imitate the morphological phenomena of lifewe have to devise a system which can divide. It must be able todivide, and to segment as--grossly--a vibrating plate or rod does, oras an icicle can do as it becomes ribbed in a continuous stream ofwater; but with this distinction, that the distribution of chemicaldifferences and properties must simultaneously be decided and disposedin orderly relation to the pattern of the segmentation. Even if amodel which would do this could be constructed it might prove to be auseful beginning. 

This may be looking too far ahead. If we had to choose some one pieceof more proximate knowledge which we would more especially like toacquire, I suppose we should ask for the secret of interracialsterility. Nothing has yet been discovered to remove the gravedifficulty, by which Huxley in particular was so much oppressed, thatamong the many varieties produced under domestication--which we allregard as analogous to the species seen in nature--no clear case ofinterracial sterility has been demonstrated. The phenomenon isprobably the only one to which the domesticated products seem toafford no parallel. No solution of the difficulty can be offered whichhas positive value, but it is perhaps worth considering the facts inthe light of modern ideas. It should be observed that we are notdiscussing incompatibility of two species to produce offspring (atotally distinct phenomenon), but the sterility of the offspring whichmany of them do produce. 

When two species, both perfectly fertile severally, produce on crossing asterile progeny, there is a presumption that the sterility is due to thedevelopment in the hybrid of some substance which can only be formed by themeeting of two complementary factors. That some such account is correct inessence may be inferred from the well-known observation that if the hybridis not totally sterile but only partially so, and thus is able to form somegood germ-cells which develop into new individuals, the sterility of thesedaughter-individuals is sensibly reduced or may be entirely absent. Thefertility once re-established, the sterility does not return in the laterprogeny, a fact strongly suggestive of segregation. Now if the sterility ofthe cross-bred be really the consequence of the meeting of twocomplementary factors, we see that the phenomenon could only be producedamong the divergent offspring of one species by the acquisition of at least_two_ new factors; for if the acquisition of a single factor causedsterility the line would then end. Moreover each factor must be separatelyacquired by distinct individuals, for if both were present together, thepossessors would by hypothesis be sterile. And in order to imitate the caseof species each of these factors must be acquired by distinct breeds. Thefactors need not, and probably would not, produce any other perceptibleeffects; they might, like the colour-factors present in white flowers, makeno difference in the form or other characters. Not till the cross wasactually made between the two complementary individuals would either factorcome into play, and the effects even then might be unobserved until anattempt was made to breed from the cross-bred. 

Next, if the factors responsible for sterility were acquired, theywould in all probability be peculiar to certain individuals and wouldnot readily be distributed to the whole breed. Any member of the breedalso into which _both_ the factors were introduced would drop out ofthe pedigree by virtue of its sterility. Hence the evidence that thevarious domesticated breeds say of dogs or fowls can when matedtogether produce fertile offspring, is beside the mark. The realquestion is, Do they ever produce sterile offspring? I think theevidence is clearly that sometimes they do, oftener perhaps than iscommonly supposed. These suggestions are quite amenable toexperimental tests. The most obvious way to begin is to get a pair ofparents which are known to have had any sterile offspring, and to findthe proportions in which these steriles were produced. If, as Ianticipate, these proportions are found to be definite, the rest issimple. 

In passing, certain other considerations may be referred to. First, that there are observations favouring the view that the production oftotally sterile cross-breds is seldom a universal property of twospecies, and that it may be a matter of individuals, which is justwhat on the view here proposed would be expected. Moreover, as we allknow now, though incompatibility may be dependent to some extent onthe degree to which the species are dissimilar, no such principle canbe demonstrated to determine sterility or fertility in general. Forexample, though all our Finches can breed together, the hybrids areall sterile. Of Ducks some species can breed together withoutproducing the slightest sterility; others have totally sterileoffspring, and so on. The hybrids between several _genera_ of Orchidsare perfectly fertile on the female side, and some on the male sidealso, but the hybrids produced between the Turnip (_Brassica napus_)and the Swede (_Brassica campestris_), which, according to ourestimates of affinity, should be nearly allied forms, are totallysterile. [73] Lastly, it may be recalled that in sterility we arealmost certainly considering a meristic phenomenon. _Failure todivide_ is, we may feel fairly sure, the immediate "cause" of thesterility. Now, though we know very little about the heredity ofmeristic differences, all that we do know points to the conclusionthat the less-divided is dominant to the more-divided, and we are thusjustified in supposing that there are factors which can arrest orprevent cell-division. My conjecture therefore is that in the case ofsterility of cross-breds we see the effect produced by a complementarypair of such factors. This and many similar problems are now open toour analysis. 

The question is sometimes asked, Do the new lights on Variation andHeredity make the process of Evolution easier to understand? On thewhole the answer may be given that they do. There is some appearanceof loss of simplicity, but the gain is real. As was said above, thetime is not ripe for the discussion of the origin of species. Withfaith in Evolution unshaken--if indeed the word faith can be used inapplication to that which is certain--we look on the manner andcausation of adapted differentiation as still wholly mysterious. AsSamuel Butler so truly said: "To me it seems that the 'Origin ofVariation, ' whatever it is, is the only true 'Origin of Species, '"[74]and of that Origin not one of us knows anything. But givenVariation--and it is given: assuming further that the variations arenot guided into paths of adaptation--and both to the Darwinian and tothe modern school this hypothesis appears to be sound if unproven--anevolution of species proceeding by definite steps is more, rather thanless, easy to imagine than an evolution proceeding by the accumulationof indefinite and insensible steps. Those who have lost themselves incontemplating the miracles of Adaptation (whether real or spurious)have not unnaturally fixed their hopes rather on the indefinite thanon the definite changes. The reasons are obvious. By suggesting thatthe steps through which an adaptative mechanism arose were indefiniteand insensible, all further trouble is spared. While it could be saidthat species arise by an insensible and imperceptible process ofvariation, there was clearly no use in tiring ourselves by trying toperceive that process. This labour-saving counsel found great favour. All that had to be done to develop evolution-theory was to discoverthe good in everything, a task which, in the complete absence of anycontrol or test whereby to check the truth of the discovery, is notvery onerous. The doctrine "_que tout est au mieux_" was thereforepreached with fresh vigour, and examples of that illuminatingprinciple were discovered with a facility that Pangloss himself mighthave envied, till at last even the spectators wearied of such dazzlingperformances. 

But in all seriousness, why should indefinite and unlimited variationhave been regarded as a more probable account of the origin ofAdaptation? Only, I think, because the obstacle was shifted one planeback, and so looked rather less prominent. The abundance ofAdaptation, we all grant, is an immense, almost an unsurpassabledifficulty in all non-Lamarckian views of Evolution; but if the stepsby which that adaptation arose were fortuitious, to imagine theminsensible is assuredly no help. In one most important respect indeed, as has often been observed, it is a multiplication of troubles. Forthe smaller the steps, the less could Natural Selection act upon them. Definite variations--and of the occurrence of definite variations inabundance we have now the most convincing proof--have at least theobvious merit that they can make and often do make a real differencein the chances of life. 

There is another aspect of the Adaptation problem to which I canallude very briefly. May not our present ideas of the universality andprecision of Adaptation be greatly exaggerated? The fit of organism toits environment is not after all so very close--a propositionunwelcome perhaps, but one which could be illustrated by very copiousevidence. Natural Selection is stern, but she has her tolerant moods. 

We have now most certain and irrefragable proof that much definitenessexists in living things apart from Selection, and also much that mayvery well have been preserved and so in a sense constituted bySelection. Here the matter is likely to rest. There is a passage inthe sixth edition of the _Origin_ which has I think been overlooked. On page 70 Darwin says, "The tuft of hair on the breast of the wildturkey-cock cannot be of any use, and it is doubtful whether it can beornamental in the eyes of the female bird. " This tuft of hair is amost definite and unusual structure, and I am afraid that the remarkthat it "cannot be of any use" may have been made inadvertently; butit may have been intended, for in the first edition the usualqualification was given and must therefore have been deliberatelyexcised. Anyhow I should like to think that Darwin did throw over thattuft of hair, and that he felt relief when he had done so. Whetherhowever we have his great authority for such a course or not, I feelquite sure that we shall be rightly interpreting the facts of natureif we cease to expect to find purposefulness wherever we meet withdefinite structures or patterns. Such things are, as often as not, Isuspect rather of the nature of tool-marks, mere incidents ofmanufacture, benefiting their possessor not more than the wire-marksin a sheet of paper, or the ribbing on the bottom of an oriental platerenders those objects more attractive in our eyes. 

If Variation may be in any way definite, the question once morearises, may it not be definite in direction? The belief that it is hashad many supporters, from Lamarck onwards, who held that it was guidedby need, and others who, like Nägeli, while laying no emphasis onneed, yet were convinced that there was guidance of some kind. Thelatter view under the name of "Orthogenesis, " devised I believe byEimer, at the present day commends itself to some naturalists. Theobjection to such a suggestion is of course that no fragment of realevidence can be produced in its support. On the other hand, with theexperimental proof that variation consists largely in the unpackingand repacking of an original complexity, it is not so certain as wemight like to think that the order of these events is notpredetermined. 

For instance the original "pack" may have been made in such a way thatat the _n_th division of the germ-cells of a Sweet Pea a colour-factormight be dropped, and that at the _n_+_n_th division the hoodedvariety be given off, and so on. I see no ground whatever for holdingsuch a view, but in fairness the possibility should not be forgotten, and in the light of modern research it scarcely looks so absurdlyimprobable as before. 

No one can survey the work of recent years without perceiving thatevolutionary orthodoxy developed too fast, and that a great deal hasgot to come down; but this satisfaction at least remains, that in theexperimental methods which Mendel inaugurated, we have means ofreaching certainty in regard to the physiology of Heredity andVariation upon which a more lasting structure may be built. 

FOOTNOTES:

[Footnote 56: _Vénus Physique, contenant deux Dissertations, l'une surl'origine des Hommes et des Animaux_; _Et l'autre sur l'origine desNoirs_, La Haye, 1746, pp. 124 and 129. For an introduction to thewritings of Maupertuis I am indebted to an article by ProfessorLovejoy in _Popular Sci. Monthly_, 1902. ]

[Footnote 57: For the fullest account of the views of these pioneersof Evolution, see the works of Samuel Butler, especially _Evolution, Old and New_ (2nd edit. ) 1882. Butler's claims on behalf of Buffonhave met with some acceptance; but after reading what Butler has said, and a considerable part of Buffon's own works, the word "hinted" seemsto me a sufficiently correct description of the part he played. It isinteresting to note that in the chapter on the Ass, which containssome of his evolutionary passages, there is a reference to "_plusieursidées très-élevées sur la génération_" contained in the Letters ofMaupertuis. ]

[Footnote 58: See especially W. Lawrence, _Lectures on Physiology_, London, 1823, pp. 213 f. ]

[Footnote 59: See the chapter contributed to the _Life and Letters ofCharles Darwin_, II. P. 195. I do not clearly understand the sense inwhich Darwin wrote (Autobiography, _ibid. _ I. P. 87): "It hassometimes been said that the success of the _Origin_ proved 'that thesubject was in the air, ' or 'that men's minds were prepared for it. ' Ido not think that this is strictly true, for I occasionally soundednot a few naturalists, and never happened to come across a single onewho seemed to doubt about the permanence of species. " This experiencemay perhaps have been an accident due to Darwin's isolation. Theliterature of the period abounds with indications of "criticalexpectancy. " A most interesting expression of that feeling is given inthe charming account of the "Early Days of Darwinism" by AlfredNewton, _Macmillan's Magazine_, LVII. 1888, p. 241. He tells how in1858 when spending a dreary summer in Iceland, he and his friend, theornithologist John Wolley, in default of active occupation, spenttheir days in discussion. "Both of us taking a keen interest inNatural History, it was but reasonable that a question, which in thosedays was always coming up wherever two or more naturalists weregathered together, should be continually recurring. That question was, 'What is a species?' and connected therewith was the other question, 'How did a species begin?'. .. Now we were of course fairly wellacquainted with what had been published on these subjects. " He thenenumerates some of these publications, mentioning among others T. Vernon Wollaston's _Variation of Species_--a work which has in myopinion never been adequately appreciated. He proceeds: "Of course wenever arrived at anything like a solution of these problems, generalor special, but we felt very strongly that a solution ought to befound, and that quickly, if the study of Botany and Zoology was tomake any great advance. " He then describes how on his return home hereceived the famous number of the _Linnean Journal_ on a certainevening. "I sat up late that night to read it; and never shall Iforget the impression it made upon me. Herein was contained aperfectly simple solution of all the difficulties which had beentroubling me for months past. .. . I went to bed satisfied that asolution had been found. "]

[Footnote 60: _Origin_, 6th edit. (1882), p. 421. ]

[Footnote 61: Whatever be our estimate of the importance of NaturalSelection, in this we all agree. Samuel Butler, the most brilliant, and by far the most interesting of Darwin's opponents--whose works areat length emerging from oblivion--in his Preface (1882) to the 2ndedition of _Evolution, Old and New_, repeats his earlier expression ofhomage to one whom he had come to regard as an enemy: "To the end oftime, if the question be asked, 'Who taught people to believe inEvolution?' the answer must be that it was Mr. Darwin. This is true, and it is hard to see what palm of higher praise can be awarded to anyphilosopher. "]

[Footnote 62: _Life and Letters_, I. Pp. 276 and 83. ]

[Footnote 63: This isolation of the systematists is the one mostmelancholy sequela of Darwinism. It seems an irony that we should readin the peroration to the _Origin_ that when the Darwinian view isaccepted "Systematists will be able to pursue their labours as atpresent; but they will not be incessantly haunted by the shadowy doubtwhether this or that form be a true species. This, I feel sure, and Ispeak after experience, will be no slight relief. The endless disputeswhether or not some fifty species of British brambles are good specieswill cease. " _Origin_, 6th edit. (1882), p. 425. True they have ceasedto attract the attention of those who lead opinion, but anyone whowill turn to the literature of systematics will find that they havenot ceased in any other sense. Should there not be somethingdisquieting in the fact that among the workers who come most intocontact with specific differences, are to be found the only men whohave failed to be persuaded of the unreality of those differences?]

[Footnote 64: 6th edit. Pp. 109 and 401. See Butler, _Essays on Life, Art, and Science_, p. 265, reprinted 1908, and _Evolution, Old andNew_, chap. XXII. (2nd edit. ), 1882. ]

[Footnote 65: W. Lawrence was one of the few who consistentlymaintained the contrary opinion. Prichard, who previously hadexpressed himself in the same sense, does not, I believe, repeat theseviews in his later writings, and there are signs that he came tobelieve in the transmission of acquired habits. See Lawrence, _Lect. Physiol. _ 1823, pp. 436-437, 447. Prichard, Edin. Inaug. Disp. 1808[not seen by me], quoted _ibid. _ and _Nat. Hist. Man_, 1843, pp. 34f. ]

[Footnote 66: It is interesting to see how nearly Butler was led bynatural penetration, and from absolutely opposite conclusions, back tothis underlying truth: "So that each ovum when impregnate should beconsidered not as descended from its ancestors, but as being acontinuation of the personality of every ovum in the chain of itsancestry, which every ovum _it actually is_ quite as truly as theoctogenarian _is_ the same identity with the ovum from which he hasbeen developed. This process cannot stop short of the primordial cell, which again will probably turn out to be but a brief resting-place. Wetherefore prove each one of us to _be actually_ the primordial cellwhich never died nor dies, but has differentiated itself into the lifeof the world, all living beings whatever, being one with it andmembers one of another, " _Life and Habit_, 1878, p. 86. ]

[Footnote 67: This view is no doubt contrary to the received opinion. I am however interested to see it lately maintained by Driesch(_Science and Philosophy of the Organism_, London, 1907, p. 233), andfrom the recent observations of Godlewski it has received distinctexperimental support. ]

[Footnote 68: In other words, the ova are each _either_ female, _ormale_ (i. E. Non-female), but the sperms are all non-female. ]

[Footnote 69: Morgan, _Proc. Soc. Exp. Biol. Med. _ V. 1908, and vonBaehr, _Zool. Anz. _ XXXII. P. 507, 1908. ]

[Footnote 70: As Wilson has proved, the unpaired body is not auniversal feature even in those orders in which it has been observed. Nearly allied types may differ. In some it is altogether unpaired. Inothers it is paired with a body of much smaller size, and by selectionof various types all gradations can be demonstrated ranging to thecondition in which the members of the pair are indistinguishable fromeach other. ]

[Footnote 71: I have in view, for example, the marvellous and specificphenomena of regeneration, and those discovered by the students of"_Entwicklungsmechanik_. " The circumstances of its occurrence herepreclude any suggestion that this regularity has been brought about bythe workings of Selection. The attempts thus to represent thephenomena have resulted in mere parodies of scientific reasoning. ]

[Footnote 72: _Vorträge über Viehzucht und Rassenerkenntniss_, p. 120, Berlin, 1872. ]

[Footnote 73: See Sutton, A. W. , _Journ. Linn. Soc. _ XXXVIII. P. 341, 1908. ]

[Footnote 74: _Life and Habit_, London, p. 263, 1878]

IV

"THE DESCENT OF MAN"

BY G. SCHWALBE

_Professor of Anatomy in the University of Strassburg_

The problem of the origin of the human race, of the descent of man, isranked by Huxley in his epoch-making book _Man's Place in Nature_, asthe deepest with which biology has to concern itself, "the question ofquestions, "--the problem which underlies all others. In the samebrilliant and lucid exposition, which appeared in 1863, soon after thepublication of Darwin's _Origin of Species_, Huxley stated his ownviews in regard to this great problem. He tells us how the idea of anatural descent of man gradually grew up in his mind. It wasespecially the assertions of Owen in regard to the total differencebetween the human and the simian brain that called forth strongdissent from the great anatomist Huxley, and he easily succeeded inshowing that Owen's supposed differences had no real existence; heeven established, on the basis of his own anatomical investigations, the proposition that the anatomical differences between the Marmosetand the Chimpanzee are much greater than those between the Chimpanzeeand Man. 

But why do we thus introduce the study of Darwin's _Descent of Man_, which is to occupy us here, by insisting on the fact that Huxley hadtaken the field in defence of the descent of man in 1863, whileDarwin's book on the subject did not appear till 1871? It is in orderthat we may clearly understand how it happened that from this timeonwards Darwin and Huxley followed the same great aim in the mostintimate association. 

Huxley and Darwin working at the same _Problema maximum_! Huxleyfiery, impetuous, eager for battle, contemptuous of the resistance ofa dull world, or energetically triumphing over it. Darwin calm, weighing every problem slowly, letting it mature thoroughly, --not afighter, yet having the greater and more lasting influence by virtueof his immense mass of critically sifted proofs. Darwin's friend, Huxley, was the first to do him justice, to understand his nature, andto find in it the reason why the detailed and carefully consideredbook on the descent of man made its appearance so late. Huxley, alwaysgenerous, never thought of claiming priority for himself. Inenthusiastic language he tells how Darwin's immortal work, _The Originof Species_, first shed light for him on the problem of the descent ofman; the recognition of a _vera causa_ in the transformation ofspecies illuminated his thoughts as with a flash. He was now contentto leave what perplexed him, what he could not yet solve, as he sayshimself, "in the mighty hands of Darwin. " Happy in the bustle ofstrife against old and deep-rooted prejudices, against intolerance andsuperstition, he wielded his sharp weapons on Darwin's behalf; wearingDarwin's armour he joyously overthrew adversary after adversary. Darwin spoke of Huxley as his "general agent. "[75] Huxley says ofhimself "I am Darwin's bulldog. "[76]

Thus Huxley openly acknowledged that it was Darwin's _Origin ofSpecies_ that first set the problem of the descent of man in its truelight, that made the question of the origin of the human race apressing one. That this was the logical consequence of his book Darwinhimself had long felt. He had been reproached with intentionallyshirking the application of his theory to Man. Let us hear what hesays on this point in his autobiography: "As soon as I had become, inthe year 1837 or 1838, convinced that species were mutableproductions, I could not avoid the belief that man must come under thesame law. Accordingly I collected notes on the subject for my ownsatisfaction, and not for a long time with any intention ofpublishing. Although in the 'Origin of Species' the derivation of anyparticular species is never discussed, yet I thought it best, in order_that no honourable man should accuse me of concealing my views_, [77]to add that by the work 'light would be thrown on the origin of manand his history. ' It would have been useless and injurious to thesuccess of the book to have paraded, without giving any evidence, myconviction with respect to his origin. "[78]

In a letter written in January, 1860, to the Rev. L. Blomefield, Darwin expresses himself in similar terms. "With respect to man, I amvery far from wishing to obtrude my belief; but I thought it dishonestto quite conceal my opinion. "[79]

The brief allusion in the _Origin of Species_ is so far from prominentand so incidental that it was excusable to assume that Darwin had nottouched upon the descent of man in this work. It was solely the desireto have his mass of evidence sufficiently complete, solely Darwin'sgreat characteristic of never publishing till he had carefully weighedall aspects of his subject for years, solely, in short, his mostfastidious scientific conscience that restrained him from challengingthe world in 1859 with a book in which the theory of the descent ofman was fully set forth. Three years, frequently interrupted byill-health, were needed for the actual writing of the book:[80] thefirst edition, which appeared in 1871, was followed in 1874 by a muchimproved second edition, the preparation of which he very reluctantlyundertook. [81]

This, briefly, is the history of the work, which, with the _Origin ofSpecies_, marks an epoch in the history of biological sciences--thework with which the cautious, peace-loving investigator ventured forthfrom his contemplative life into the arena of strife and unrest, andlaid himself open to all the annoyances that deep-rooted belief andprejudice, and the prevailing tendency of scientific thought at thetime could devise. 

Darwin did not take this step lightly. Of great interest in thisconnection is a letter written to Wallace on Dec. 22, 1857, [82] inwhich he says, "You ask me whether I shall discuss 'man. ' I think Ishall avoid the whole subject, as so surrounded with prejudices;though I fully admit that it is the highest and most interestingproblem for the naturalist. " But his conscientiousness compelled himto state briefly his opinion on the subject in the _Origin of Species_in 1859. Nevertheless he did not escape reproaches for having been soreticent. This is unmistakably apparent from a letter to Fritz Müllerdated Feb. 22 [1869?], in which he says: "I am thinking of writing alittle essay on the Origin of Mankind, as I have been taunted withconcealing my opinions. "[83]

It might be thought that Darwin behaved thus hesitatingly, and was soslow in deciding on the full publication of his collected material inregard to the descent of man, because he had religious difficulties toovercome. 

But this was not the case, as we can see from his admirable confessionof faith, the publication of which we owe to his son Francis. [84]Whoever wishes really to understand the lofty character of this greatman should read these immortal lines in which he unfolds to us insimple and straightforward words the development of his conception ofthe universe. He describes how, though he was still quite orthodoxduring his voyage round the world on board the _Beagle_, he camegradually to see, shortly afterwards (1836-1839) that the OldTestament was no more to be trusted than the Sacred Books of theHindoos; the miracles by which Christianity is supported, thediscrepancies between the accounts in the different Gospels, graduallyled him to disbelieve in Christianity as a divine revelation. "Thus, "he writes, [85] "disbelief crept over me at a very slow rate, but wasat last complete. The rate was so slow that I felt no distress. " ButDarwin was too modest to presume to go beyond the limits laid down byscience. He wanted nothing more than to be able to go, freely andunhampered by belief in authority or in the Bible, as far as humanknowledge could lead him. We learn this from the concluding words ofhis chapter on religion "The mystery of the beginning of all things isinsoluble by us; and I for one must be content to remain anAgnostic. "[86]

Darwin was always very unwilling to give publicity to his views inregard to religion. In a letter to Asa Gray on May 22, 1860, [87] hedeclares that it is always painful to him to have to enter intodiscussion of religious problems. He had, he said, no intention ofwriting atheistically. 

Finally, let us cite one characteristic sentence from a letter fromDarwin to C. Ridley[88] (Nov. 28, 1878). A clergyman, Dr. Pusey, hadasserted that Darwin had written the _Origin of Species_ with somerelation to theology. Darwin writes emphatically, "Many years ago whenI was collecting facts for the 'Origin, ' my belief in what is called apersonal God was as firm as that of Dr. Pusey himself, and as to theeternity of matter I never troubled myself about such insolublequestions. " The expression "many years ago" refers to the time of hisvoyage round the world, as has already been pointed out. Darwin meansby this utterance that the views which had gradually developed in hismind in regard to the origin of species were quite compatible with thefaith of the Church. 

If we consider all these utterances of Darwin in regard to religionand to his outlook on life (Weltanschauung), we shall see at least somuch, that religious reflection could in no way have influenced him inregard to the writing and publishing of his book on _The Descent ofMan_. Darwin had early won for himself freedom of thought, and to thisfreedom he remained true to the end of his life, uninfluenced by thecustoms and opinions of the world around him. 

Darwin was thus inwardly fortified and armed against the host ofcalumnies, accusations, and attacks called forth by the publication ofthe _Origin of Species_, and to an even greater extent by theappearance of the _Descent of Man_. But in his defence he could relyon the aid of a band of distinguished auxiliaries of the rarestability. His faithful confederate, Huxley, was joined by the botanistHooker, and, after longer resistance, by the famous geologist Lyell, whose "conversion" afforded Darwin peculiar satisfaction. All threetook the field with enthusiasm in defence of the natural descent ofman. From Wallace, on the other hand, though he shared with him theidea of natural selection, Darwin got no support in this matter. Wallace expressed himself in a strange manner. He admitted everythingin regard to the morphological descent of man, but maintained, in amystic way, that something else, something of a spiritual nature musthave been added to what man inherited from his animal ancestors. Darwin, whose esteem for Wallace was extraordinarily high, could notunderstand how he could give utterance to such a mystical view inregard to man; the idea seemed to him so "incredibly strange" that hethought some one else must have added these sentences to Wallace'spaper. 

Even now there are thinkers who, like Wallace, shrink from applying toman the ultimate consequences of the theory of descent. The idea thatman is derived from ape-like forms is to them unpleasant andhumiliating. 

So far I have been depicting the development of Darwin's work on thedescent of man. In what follows I shall endeavour to give a condensedsurvey of the contents of the book. 

It must at once be said that the contents of Darwin's work fall intotwo parts, dealing with entirely different subjects. _The Descent ofMan_ includes a very detailed investigation in regard to secondarysexual characters in the animal series, and on this investigationDarwin founded a new theory, that of sexual selection. Withastonishing patience he gathered together an immense mass of material, and showed, in regard to Arthropods and Vertebrates, the widedistribution of secondary characters, which develop almost exclusivelyin the male, and which enable him, on the one hand, to get the betterof his rivals in the struggle for the female by the greater perfectionof his weapons, and, on the other hand, to offer greater allurementsto the female through the higher development of decorative characters, of song, or of scent-producing glands. The best equipped males willthus crowd out the less well-equipped in the matter of reproduction, and thus the relevant characters will be increased and perfectedthrough sexual selection. It is, of course, a necessary assumptionthat these secondary sexual characters may be transmitted to thefemale, although perhaps in rudimentary form. 

As we have said, this story of sexual selection takes up a great dealof space in Darwin's book, and it need only be considered here in sofar as Darwin applied it to the descent of man. To this latter problemthe whole of Part I is devoted, while Part III contains a discussionof sexual selection in relation to man, and a general summary. PartII treats of sexual selection in general, and may be disregarded inour present study. Moreover, many interesting details must necessarilybe passed over in what follows, for want of space. 

The first part of the _Descent of Man_ begins with an enumeration ofthe proofs of the animal descent of man taken from the structure ofthe human body. Darwin chiefly emphasises the fact that the human bodyconsists of the same organs and of the same tissues as those of theother mammals; he shows also that man is subject to the same diseasesand tormented by the same parasites as the apes. He further dwells onthe general agreement exhibited by young embryonic forms, and heillustrates this by two figures placed one above the other, onerepresenting a human embryo, after Ecker, the other a dog embryo, after Bischoff. [89]

Darwin finds further proofs of the animal origin of man in the reducedstructures, in themselves extremely variable, which are eitherabsolutely useless to their possessors, or of so little use that theycould never have developed under existing conditions. Of such vestigeshe enumerates: the defective development of the _panniculus carnosus_(muscle of the skin) so widely distributed among mammals, theear-muscles, the occasional persistence of the animal ear-point inman, the rudimentary nictitating membrane (_plica semilunaris_) in thehuman eye, the slight development of the organ of smell, the generalhairiness of the human body, the frequently defective development orentire absence of the third molar (the wisdom tooth), the vermiformappendix, the occasional reappearance of a bony canal (_foramensupracondyloideum_) at the lower end of the humerus, the rudimentarytail of man (the so-called taillessness), and so on. Of theserudimentary structures the occasional occurrence of the animalear-point in man is most fully discussed. Darwin's attention wascalled to this interesting structure by the sculptor Woolner. Hefigures such a case observed in man, and also the head of an allegedorang-foetus, the photograph of which he received from Nitsche. 

Darwin's interpretation of Woolner's case as having arisen through afolding over of the free edge of a pointed ear has been fully borneout by my investigations on the external ear. [90] In particular, itwas established by these investigations that the human foetus, aboutthe middle of its embryonic life, possesses a pointed ear somewhatsimilar to that of the monkey genus Macacus. One of Darwin'sstatements in regard to the head of the orang-foetus must becorrected. A _large_ ear with a point is shown in the photograph, [91]but it can easily be demonstrated--and Deniker has already pointedthis out--that the figure is not that of an orang foetus at all, forthat form has much smaller ears with no point; nor can it be agibbon-foetus, as Deniker supposes, for the gibbon ear is also withouta point. I myself regard it as that of a Macacus-embryo. But thismistake, which is due to Nitsche, in no way affects the factrecognised by Darwin, that ear-forms showing the point characteristicof the animal ear occur in man with extraordinary frequency. 

Finally, there is a discussion of those rudimentary structures whichoccur only in _one_ sex, such as the rudimentary mammary glands in themale, the vesicula prostatica, which corresponds to the uterus of thefemale, and others. All these facts tell in favour of the commondescent of man and all other vertebrates. The conclusion of thissection is characteristic: "_It is only our natural prejudice, andthat arrogance which made our forefathers declare that they weredescended from demi-gods, which leads us to demur to this conclusion. But the time will before long come, when it will be thought wonderfulthat naturalists, who were well acquainted with the comparativestructure and development of man, and other mammals, should havebelieved that each was the work of a separate act of creation. _"[92]

In the second chapter there is a more detailed discussion, again basedupon an extraordinary wealth of facts, of the problem as to the mannerin which, and the causes through which, man evolved from a lower form. Precisely the same causes are here suggested for the origin of man, asfor the origin of species in general. Variability, which is anecessary assumption in regard to all transformations, occurs in manto a high degree. Moreover, the rapid multiplication of the human racecreates conditions which necessitate an energetic struggle forexistence, and thus afford scope for the intervention of naturalselection. Of the exercise of _artificial_ selection in the humanrace, there is nothing to be said, unless we cite such cases as thegrenadiers of Frederick William I, or the population of ancientSparta. In the passages already referred to and in those which follow, the transmission of acquired characters, upon which Darwin does notdwell, is taken for granted. In man, direct effects of changedconditions can be demonstrated (for instance in regard to bodilysize), and there are also proofs of the influence exerted on hisphysical constitution by increased use or disuse. Reference is heremade to the fact, established by Forbes, that the Quechua Indians ofthe high plateaus of Peru show a striking development of lungs andthorax, as a result of living constantly at high altitudes. 

Such special forms of variation as arrests of development(microcephalism) and reversion to lower forms are next discussed. Darwin himself felt[93] that these subjects are so nearly related tothe cases mentioned in the first chapter, that many of them might aswell have been dealt with there. It seems to me that it would havebeen better so, for the citation of additional instances of reversionat this place rather disturbs the logical sequence of his ideas as tothe conditions which have brought about the evolution of man fromlower forms. The instances of reversion here discussed aremicrocephalism, which Darwin wrongly interpreted as atavistic, supernumerary mammae, supernumerary digits, bicornuate uterus, thedevelopment of abnormal muscles, and so on. Brief mention is also madeof correlative variations observed in man. 

Darwin next discusses the question as to the manner in which manattained to the erect position from the state of a climbing quadruped. Here again he puts the influence of Natural Selection in the firstrank. The immediate progenitors of man had to maintain a struggle forexistence in which success was to the more intelligent, and to thosewith social instincts. The hand of these climbing ancestors, which hadlittle skill and served mainly for locomotion, could only undergofurther development when some early member of the Primate series cameto live more on the ground and less among trees. 

A bipedal existence thus became possible, and with it the liberationof the hand from locomotion, and the one-sided development of thehuman foot. The upright position brought about correlated variationsin the bodily structure; with the free use of the hand it becamepossible to manufacture weapons and to use them; and this againresulted in a degeneration of the powerful canine teeth and the jaws, which were then no longer necessary for defence. Above all, however, the intelligence immediately increased, and with it skull and brain. The nakedness of man, and the absence of a tail (rudimentariness ofthe tail vertebrae) are next discussed. Darwin is inclined toattribute the nakedness of man, not to the action of natural selectionon ancestors who originally inhabited a tropical land, but to sexualselection, which, for aesthetic reasons, brought about the loss of thehairy covering in man, or primarily in woman. An interestingdiscussion of the loss of the tail, which, however, man shares withthe anthropoid apes, some other monkeys and lemurs, forms theconclusion of the almost superabundant material which Darwin workedup in the second chapter. His object was to show that some of the mostdistinctive human characters are in all probability directly orindirectly due to natural selection. With characteristic modesty headds:[94] "Hence, if I have erred in giving to natural selection greatpower, which I am very far from admitting, or in having exaggeratedits power, which is in itself probable, I have at least, as I hope, done good service in aiding to overthrow the dogma of separatecreations. " At the end of the chapter he touches upon the objection asto man's helpless and defenceless condition. Against this he urges hisintelligence and social instincts. 

The two following chapters contain a detailed discussion of theobjections drawn from the supposed great differences between themental powers of men and animals. Darwin at once admits that thedifferences are enormous, but not that any fundamental differencebetween the two can be found. Very characteristic of him is thefollowing passage: "In what manner the mental powers were firstdeveloped in the lowest organisms, is as hopeless an enquiry as howlife itself first originated. These are problems for the distantfuture, if they are ever to be solved by man. "[95]

After some brief observations on instinct and intelligence, Darwinbrings forward evidence to show that the greater number of theemotional states, such as pleasure and pain, happiness and misery, love and hate are common to man and the higher animals. He goes on togive various examples showing that wonder and curiosity, imitation, attention, memory and imagination (dreams of animals), can also beobserved in the higher mammals, especially in apes. In regard even toreason there are no sharply defined limits. A certain faculty ofdeliberation is characteristic of some animals, and the morethoroughly we know an animal the more intelligence we are inclined tocredit it with. Examples are brought forward of the intelligent anddeliberate actions of apes, dogs and elephants. But although nosharply defined differences exist between man and animals, there is, nevertheless, a series of other mental powers which arecharacteristics usually regarded as absolutely peculiar to man. Someof these characteristics are examined in detail, and it is shown thatthe arguments drawn from them are not conclusive. Man alone is said tobe capable of progressive improvement; but against this must be placedas something analogous in animals, the fact that they learn cunningand caution through long continued persecution. Even the use of toolsis not in itself peculiar to man (monkeys use sticks, stones andtwigs), but man alone fashions and uses implements _designed for aspecial purpose_. In this connection the remarks taken from Lubbock inregard to the origin and gradual development of the earliest flintimplements will be read with interest; these are similar to theobservations on modern eoliths, and their bearing on the developmentof the stone industry. It is interesting to learn from a letter toHooker, [96] that Darwin himself at first doubted whether the stoneimplements discovered by Boucher de Perthes were really of the natureof tools. With the relentless candour as to himself whichcharacterised him, he writes four years later in a letter to Lyell inregard to this view of Boucher de Perthes' discoveries: "I knowsomething about his errors, and looked at his book many years ago, andam ashamed to think that I concluded the whole was rubbish! Yet he hasdone for man something like what Agassiz did for glaciers. "[97]

To return to Darwin's further comparisons between the higher mental powersof man and animals; He takes much of the force from the argument that manalone is capable of abstraction and self-consciousness by his ownobservations on dogs. One of the main differences between man and animals, speech, receives detailed treatment. He points out that various animals(birds, monkeys, dogs) have a large number of different sounds fordifferent emotions, that, further, man produces in common with animals awhole series of inarticulate cries combined with gestures, and that dogslearn to understand whole sentences of human speech. In regard to humanlanguage, Darwin expresses a view contrary to that held by Max Müller:[98]"I cannot doubt that language owes its origin to the imitation andmodification of various natural sounds, the voices of other animals, andman's own instinctive cries, aided by signs and gestures. " The developmentof actual language presupposes a higher degree of intelligence than isfound in any kind of ape. Darwin remarks on this point:[99] "The fact ofthe higher apes not using their vocal organs for speech no doubt depends ontheir intelligence not having been sufficiently advanced. "

The sense of beauty, too, has been alleged to be peculiar to man. Inrefutation of this assertion Darwin points to the decorative coloursof birds, which are used for display. And to the last objection, thatman alone has religion, that he alone has a belief in God, it isanswered "that numerous races have existed, and still exist, who haveno idea of one or more gods, and who have no words in their languagesto express such an idea. "[100]

The result of the investigations recorded in this chapter is to showthat, great as the difference in mental powers between man and thehigher animals may be, it is undoubtedly only a difference "of degreeand not of kind. "[101]

In the fourth chapter Darwin deals with the _moral sense_ or_conscience_, which is the most important of all differences betweenman and animals. It is a result of social instincts, which lead tosympathy for other members of the same society, to non-egoisticactions for the good of others. Darwin shows that social tendenciesare found among many animals, and that among these love andkin-sympathy exist, and he gives examples of animals (especially dogs)which may exhibit characters that we should call moral in man (e. G. Disinterested self-sacrifice for the sake of others). The earlyape-like progenitors of the human race were undoubtedly social. Withthe increase of intelligence the moral sense develops farther; withthe acquisition of speech public opinion arises, and finally, moralsense becomes habit. The rest of Darwin's detailed discussions onmoral philosophy may be passed over. 

The fifth chapter may be very briefly summarised. In it Darwin showsthat the intellectual and moral faculties are perfected throughnatural selection. He inquires how it can come about that a tribe at alow level of evolution attains to a higher, although the best andbravest among them often pay for their fidelity and courage with theirlives without leaving any descendants. In this case it is thesentiment of glory, praise and blame, the admiration of others, whichbring about the increase of the better members of the tribe. Property, fixed dwellings, and the association of families into a community arealso indispensable requirements for civilisation. In the longer secondsection of the fifth chapter Darwin acts mainly as recorder. On thebasis of numerous investigations, especially those of Greg, Wallace, and Galton, he inquires how far the influence of natural selection canbe demonstrated in regard to civilised nations. In the final section, which deals with the proofs that all civilised nations were oncebarbarians, Darwin again uses the results gained by otherinvestigators, such as Lubbock and Tylor. There are two sets of factswhich prove the proposition in question. In the first place, we findtraces of a former lower state in the customs and beliefs of allcivilised nations, and in the second place, there are proofs to showthat savage races are independently able to raise themselves a fewsteps in the scale of civilisation, and that they have thus raisedthemselves. 

In the sixth chapter of the work, Morphology comes into the foregroundonce more. Darwin first goes back, however, to the argument based onthe great difference between the mental powers of the highest animalsand those of man. That this is only quantitative, not qualitative, hehas already shown. Very instructive in this connection is thereference to the enormous difference in mental powers in anotherclass. No one would draw from the fact that the cochineal insect(Coccus) and the ant exhibit enormous differences in their mentalpowers, the conclusion that the ant should therefore be regarded assomething quite distinct, and withdrawn from the class of insectsaltogether. 

Darwin next attempts to establish the _specific_ genealogical tree ofman, and carefully weighs the differences and resemblances between thedifferent families of the Primates. The erect position of man is anadaptive character, just as are the various characters referable toaquatic life in the seals, which, notwithstanding these, are ranked asa mere family of the carnivores. The following utterance is verycharacteristic of Darwin:[102] "If man had not been his ownclassifier, he would never have thought of founding a separate orderfor his own reception. " In numerous characters not mentioned insystematic works, in the features of the face, in the form of thenose, in the structure of the external ear, man resembles the apes. The arrangement of the hair in man has also much in common with theapes; as also the occurrence of hair on the forehead of the humanembryo, the beard, the convergence of the hair of the upper and underarm towards the elbow, which occurs not only in the anthropoid apes, but also in some American monkeys. Darwin here adopts Wallace'sexplanation of the origin of the ascending direction of the hair inthe forearm of the orang, --that it has arisen through the habit ofholding the hands over the head in rain. But this explanation cannotbe maintained when we consider that this disposition of the hair iswidely distributed among the most different mammals, being found inthe dog, in the sloth, and in many of the lower monkeys. 

After further careful analysis of the anatomical characters Darwinreaches the conclusion that the New World monkeys (Platyrrhine) may beexcluded from the genealogical tree altogether, but that man is anoffshoot from the Old World monkeys (Catarrhine) whose progenitorsexisted as far back as the Miocene period. Among these Old Worldmonkeys the forms to which man shows the greatest resemblance are theanthropoid apes, which, like him, possess neither tail nor ischialcallosities. The platyrrhine and catarrhine monkeys have theirprimitive ancestor among extinct forms of the Lemuridae. Darwin alsotouches on the question of the original home of the human race andsupposes that it may have been in Africa, because it is there thatman's nearest relatives, the gorilla and the chimpanzee, are found. But he regards speculation on this point as useless. It is remarkablethat, in this connection, Darwin regards the loss of the hair-coveringin man as having some relation to a warm climate, while elsewhere heis inclined to make sexual selection responsible for it. Darwinrecognises the great gap between man and his nearest relatives, butsimilar gaps exist at other parts of the mammalian genealogical tree:the allied forms have become extinct. After the extermination of thelower races of mankind, on the one hand, and of the anthropoid apes onthe other, which will undoubtedly take place, the gulf will be greaterthan ever, since the baboons will then bound it on the one side, andthe white races on the other. Little weight need be attached to thelack of fossil remains to fill up this gap, since the discovery ofthese depends upon chance. The last part of the chapter is devoted toa discussion of the earlier stages in the genealogy of man. HereDarwin accepts in the main the genealogical tree, which had meantimebeen published by Haeckel, who traces the pedigree back throughMonotrems, Reptiles, Amphibians, and Fishes, to Amphioxus. 

Then follows an attempt to reconstruct, from the atavistic characters, a picture of our primitive ancestor who was undoubtedly an arborealanimal. The occurrence of rudiments of parts in one sex which onlycome to full development in the other is next discussed. This state ofthings Darwin regards as derived from an original hermaphroditism. Inregard to the mammary glands of the male he does not accept the theorythat they are vestigial, but considers them rather as not fullydeveloped. 

The last chapter of Part I deals with the question whether thedifferent races of man are to be regarded as different species, or assub-species of a race of monophyletic origin. The striking differencesbetween the races are first emphasised, and the question of thefertility or infertility of hybrids is discussed. That fertility isthe more usual is shown by the excessive fertility of the hybridpopulation of Brazil. This, and the great variability of thedistinguishing characters of the different races, as well as the factthat all grades of transition stages are found between these, whileconsiderable general agreement exists, tell in favour of the unity ofthe races and lead to the conclusion that they all had a commonprimitive ancestor. 

Darwin therefore classifies all the different races as sub-species of_one and the same species_. Then follows an interesting inquiry intothe reasons for the extinction of human races. He recognises as theultimate reason the injurious effects of a change of the conditions oflife, which may bring about an increase in infantile mortality, and adiminished fertility. It is precisely the reproductive system, amonganimals also, which is most susceptible to changes in the environment. 

The final section of this chapter deals with the formation of theraces of mankind. Darwin discusses the question how far the directeffect of different conditions of life, or the inherited effects ofincreased use or disuse may have brought about the characteristicdifferences between the different races. Even in regard to the originof the colour of the skin he rejects the transmitted effects of anoriginal difference of climate as an explanation. In so doing he isfollowing his tendency to exclude Lamarckian explanations as far aspossible. But here he makes gratuitous difficulties from which, sincenatural selection fails, there is no escape except by bringing in theprinciple of sexual selection, to which, he regarded it as possible, skin-colouring, arrangement of hair, and form of features might betraced. But with his characteristic conscientiousness he guardshimself thus: "I do not intend to assert that sexual selection willaccount for all the differences between the races. "[103]

I may be permitted a remark as to Darwin's attitude towards Lamarck. While, at an earlier stage, when he was engaged in the preliminarylabours for his immortal work, _The Origin of Species_, Darwinexpresses himself very forcibly against the views of Lamarck, speakingof Lamarckian "nonsense, "[104] and of Lamarck's "absurd, though cleverwork"[105] and expressly declaring, "I attribute very little to thedirect action of climate, etc. "[106] yet in later life he became moreand more convinced of the influence of external conditions. In 1876, that is, two years after the appearance of the second edition of _TheDescent of Man_, he writes with his usual candid honesty: "In myopinion the greatest error which I have committed, has been notallowing sufficient weight to the direct action of the environment, i. E. Food, climate, etc. Independently of a natural selection. "[107]It is certain from this change of opinion that, if he had been able tomake up his mind to issue a third edition of _The Descent of Man_, hewould have ascribed a much greater influence to the effect ofexternal conditions in explaining the different characters of theraces of man than he did in the second edition. He would alsoundoubtedly have attributed less influence to sexual selection as afactor in the origin of the different bodily characteristics, ifindeed he would not have excluded it altogether. 

In Part III of the _Descent_ two additional chapters are devoted tothe discussion of sexual selection in relation to man. These may bevery briefly referred to. Darwin here seeks to show that sexualselection has been operative on man and his primitive progenitor. Space fails me to follow out his interesting arguments. I can onlymention that he is inclined to trace back hairlessness, thedevelopment of the beard in man, and the characteristic colour of thedifferent human races to sexual selection. Since bareness of the skincould be no advantage, but rather a disadvantage, this charactercannot have been brought about by natural selection. Darwin alsorejected a direct influence of climate as a cause of the origin of theskin-colour. I have already expressed the opinion, based on thedevelopment of his views as shown in his letters, that in a thirdedition Darwin would probably have laid more stress on the influenceof external environment. He himself feels that there are gaps in hisproofs here, and says in self-criticism: "The views here advanced, onthe part which sexual selection has played in the history of man, wantscientific precision. "[108] I need here only point out that it isimpossible to explain the graduated stages of skin-colour by sexualselection, since it would have produced races sharply defined by theircolour and not united to other races by transition stages, and this, it is well known, is not the case. Moreover, the fact established byme, [109] that in all races the ventral side of the trunk is paler thanthe dorsal side, and the inner surface of the extremities paler thanthe outer side, cannot be explained by sexual selection in theDarwinian sense. 

With this I conclude my brief survey of the rich contents of Darwin'sbook. I may be permitted to conclude by quoting the magnificent finalwords of _The Descent of Man_: "We must, however, acknowledge, as itseems to me, that man, with all his noble qualities, with sympathywhich feels for the most debased, with benevolence which extends notonly to other men but to the humblest living creature, with hisgod-like intellect which has penetrated into the movements andconstitution of the solar system--with all these exalted powers--Manstill bears in his bodily frame the indelible stamp of his lowlyorigin. "[110]

What has been the fate of Darwin's doctrines since his greatachievement? How have they been received and followed up by thescientific and lay world? And what do the successors of the mightyhero and genius think now in regard to the origin of the human race?

At the present time we are incomparably more favourably placed thanDarwin was for answering this question of all questions. We have atour command an incomparably greater wealth of material than he had athis disposal. And we are more fortunate than he in this respect, thatwe now know transition-forms which help to fill up the gap, stillgreat, between the lowest human races and the highest apes. Let usconsider for a little the more essential additions to our knowledgesince the publication of _The Descent of Man_. 

Since that time our knowledge of animal embryos has increasedenormously. While Darwin was obliged to content himself with comparinga human embryo with that of a dog, there are now available theyoungest embryos of monkeys of all possible groups (Orang, Gibbon, Semnopithecus, Macacus), thanks to Selenka's most successful tour inthe East Indies in search of such material. We can now comparecorresponding stages of the lower monkeys and of the Anthropoid apeswith human embryos, and convince ourselves of their great resemblanceto one another, thus strengthening enormously the armour prepared byDarwin in defence of his view on man's nearest relatives. It may besaid that Selenka's material fills up the blanks in Darwin's array ofproofs in the most satisfactory manner. 

The deepening of our knowledge of comparative anatomy also gives us muchsurer foundations than those on which Darwin was obliged to build. Just oflate there have been many workers in the domain of the anatomy of apes andlemurs, and their investigations extend to the most different organs. Ourknowledge of fossil apes and lemurs has also become much wider and moreexact since Darwin's time: the fossil lemurs have been especially worked upby Cope, Forsyth Major, Ameghino, and others. Darwin knew very little aboutfossil monkeys. He mentions two or three anthropoid apes as occurring inthe Miocene of Europe, [111] but only names _Dryopithecus_, the largest formfrom the Miocene of France. It was erroneously supposed that this form wasrelated to _Hylobates_. We now know not only a form that actually standsnear to the gibbon (_Pliopithecus_), and remains of other anthropoids(_Pliohylobates_ and the fossil chimpanzee, _Palaeopithecus_), but alsoseveral lower catarrhine monkeys, of which _Mesopithecus_, a form nearlyrelated to the modern Sacred Monkeys (a species of _Semnopithecus_) andfound in strata of the Miocene period in Greece, is the most important. Quite recently, too, Ameghino's investigations have made us acquainted withfossil monkeys from South America (_Anthropops_, _Homunculus_), which, according to their discoverer, are to be regarded as in the line of humandescent. 

What Darwin missed most of all--intermediate forms between apes andman--has been recently furnished. E. Dubois, as is well known, discovered in 1893, near Trinil in Java, in the alluvial deposits ofthe river Bengawan, an important form represented by a skull-cap, somemolars, and a femur. His opinion--much disputed as it has been--thatin this form, which he named _Pithecanthropus_, he has found along-desired transition-form is shared by the present writer. Andalthough the geological age of these fossils, which, according toDubois, belong to the uppermost Tertiary series, the Pliocene hasrecently been fixed at a later date (the older Diluvium), the_morphological value_ of these interesting remains, that is, theintermediate position of _Pithecanthropus_, still holds good. Volzsays with justice, [112] that even if _Pithecanthropus_ is not _the_missing link, it is undoubtedly _a_ missing link. 

As on the one hand there has been found in _Pithecanthropus_ a formwhich, though intermediate between apes and man, is nevertheless moreclosely allied to the apes, so on the other hand, much progress hasbeen made since Darwin's day in the discovery and description of theoldest human remains. Since the famous roof of a skull and the bonesof the extremities belonging to it were found in 1856 in theNeandertal near Düsseldorf, the most varied judgments have beenexpressed in regard to the significance of the remains and of theskull in particular. In Darwin's _Descent of Man_ there is only apassing allusion to them[113] in connection with the discussion of theskull-capacity, although the investigations of Schaaffhausen, King, and Huxley were then known. I believe I have shown, in a series ofpapers, that the skull in question belongs to a form different fromany of the races of man now living, and, with King and Cope, I regardit as at least a different species from living man, and have thereforedesignated it _Homo primigenius_. The form unquestionably belongs tothe older Diluvium, and in the later Diluvium human forms alreadyappear, which agree in all essential points with existing human races. 

As far back as 1886 the value of the Neandertal skull was greatlyenhanced by Fraipont's discovery of two skulls and skeletons from Spyin Belgium. These are excellently described by their discoverer, [114]and are regarded as belonging to the same group of forms as theNeandertal remains. In 1899 and the following years came the discoveryby Gorjanovič-Kramberger of different skeletal parts of at leastten individuals in a cave near Krapina in Croatia. [115] It is inparticular the form of the lower jaw which is different from that ofall recent races of man, and which clearly indicates the lowlyposition of _Homo primigenius_, while, on the other hand, thelong-known skull from Gibraltar, which I[116] have referred to _Homoprimigenius_, and which has lately been examined in detail bySollas, [117] has made us acquainted with the surprising shape of theeye-orbit, of the nose, and of the whole upper part of the face. Isolated lower jaws found at La Naulette in Belgium, and at Malarnaudin France, increase our material which is now as abundant as could bedesired. The most recent discovery of all is that of a skull dug up inAugust of this year [1908] by Klaatsch and Hauser in the lower grottoof the Le Moustier in Southern France, but this skull has not yet beenfully described. Thus _Homo primigenius_ must also be regarded asoccupying a position in the gap existing between the highest apes andthe lowest human races, _Pithecanthropus_, standing in the lower partof it, and _Homo primigenius_ in the higher, near man. In order toprevent misunderstanding, I should like here to emphasise that inarranging this structural series--anthropoid apes, _Pithecanthropus_, _Homo primigenius_, _Homo sapiens_--I have no intention ofestablishing it as a direct genealogical series. I shall havesomething to say in regard to the genetic relations of these forms, one to another, when discussing the different theories of descentcurrent at the present day. [118]

In quite a different domain from that of morphological relationship, namely in the physiological study of the blood, results have recentlybeen gained which are of the highest importance to the doctrine ofdescent. Uhlenhuth, Nuttall, and others have established the fact thatthe blood-serum of a rabbit which has previously had human bloodinjected into it, forms a precipitate with human blood. Thisbiological reaction was tried with a great variety of mammalianspecies, and it was found that those far removed from man gave noprecipitate under these conditions. But as in other cases amongmammals all nearly related forms yield an almost equally markedprecipitate, so the serum of a rabbit treated with human blood andthen added to the blood of an anthropoid ape gives _almost_ as markeda precipitate as in human blood; the reaction to the blood of thelower Eastern monkeys is weaker, that to the Western monkeys weakerstill; indeed in this last case there is only a slight clouding aftera considerable time and no actual precipitate. The blood of theLemuridae (Nuttall) gives no reaction or an extremely weak one, thatof the other mammals none whatever. We have in this not only a proofof the literal blood relationship between man and apes, but the degreeof relationship with the different main groups of apes can bedetermined beyond possibility of mistake. 

Finally, it must be briefly mentioned that in regard to remains ofhuman handicraft also, the material at our disposal has greatlyincreased of late years, that, as a result of this, the opinions ofarchaeologists have undergone many changes, and that, in particular, their views in regard to the age of the human race have been greatlyinfluenced. There is a tendency at the present time to refer theorigin of man back to Tertiary times. It is true that no remains ofTertiary man have been found, but flints have been discovered which, according to the opinion of most investigators, bear traces either ofuse, or of very primitive workmanship. Since Rutot's time, followingMortillet's example, investigators have called these "eoliths, " andthey have been traced back by Verworn to the Miocene of the Auvergne, and by Rutot even to the upper Oligocene. Although these eoliths areeven nowadays the subject of many different views, the preoccupationwith them has kept the problem of the age of the human racecontinually before us. 

Geology, too, has made great progress since the days of Darwin andLyell, and has endeavoured with satisfactory results to arrange thehuman remains of the Diluvial period in chronological order (Penck). Ido not intend to enter upon the question of the primitive home of thehuman race; since the space at my disposal will not allow of mytouching even very briefly upon all the departments of science whichare concerned in the problem of the descent of man. How Darwin wouldhave rejoiced over each of the discoveries here briefly outlined! Whatuse he would have made of the new and precious material, which wouldhave prevented the discouragement from which he suffered whenpreparing the second edition of _The Descent of Man_! But it was notgranted to him to see this progress towards filling up the gaps in hisedifice of which he was so painfully conscious. 

He did, however, have the satisfaction of seeing his ideas steadilygaining ground, notwithstanding much hostility and deep-rootedprejudice. Even in the years between the appearance of _The Origin ofSpecies_ and of the first edition of the _Descent_, the idea of anatural descent of man, which was only briefly indicated in the workof 1859, had been eagerly welcomed in some quarters. It has beenalready pointed out how brilliantly Huxley contributed to the defenceand diffusion of Darwin's doctrines, and how in _Man's Place inNature_ he has given us a classic work as a foundation for thedoctrine of the descent of man. As Huxley was Darwin's champion inEngland, so in Germany Carl Vogt, in particular, made himself masterof the Darwinian ideas. But above all it was Haeckel who, in energy, eagerness for battle, and knowledge may be placed side by side withHuxley, who took over the leadership in the controversy over the newconception of the universe. As far back as 1866, in his _GenerelleMorphologie_, he had inquired minutely into the question of thedescent of man, and not content with urging merely the general theoryof descent from lower animal forms, he drew up for the first timegenealogical trees showing the close structural relationships of thedifferent animal groups; the last of these illustrated therelationships of Mammals, and among them of all groups of thePrimates, including man. It was Haeckel's genealogical trees thatformed the basis of the special discussion of the relationships ofman, in the sixth chapter of Darwin's _Descent of Man_. 

In the last section of this essay I shall return to Haeckel'sconception of the special descent of man, the main features of whichhe still upholds, and rightly so. Haeckel has contributed more thanany one else to the spread of the Darwinian doctrine. 

I can only allow myself a few words as to the spread of the theory ofthe natural descent of man in other countries. The Parisiananthropological school, founded and guided by the genius of Broca, took up the idea of the descent of man, and made many notablecontributions to it (Broca, Manouvrier, Mahoudeau, Deniker andothers). In England itself Darwin's work did not die. Huxley took careof that, for he, with his lofty and unprejudiced mind, dominated andinspired English biology until his death on June 29, 1895. He had thesatisfaction shortly before his death of learning of Dubois'discovery, which he illustrated by a humourous sketch. [119] But thereare still many followers in Darwin's footsteps in England. Keane hasworked at the special genealogical tree of the Primates; Keith hasinquired which of the anthropoid apes has the greatest number ofcharacters in common with man; Morris concerns himself with theevolution of man in general, especially with his acquisition of theerect position. The recent discoveries of _Pithecanthropus_ and _Homoprimigenius_ are being vigorously discussed; but the present writer isnot in a position to form an opinion of the extent to which the ideaof descent has penetrated throughout England generally. 

In Italy independent work in the domain of the descent of man is beingproduced, especially by Morselli; with him are associated, in theinvestigation of related problems, Sergi and Giuffrida-Ruggeri. Fromthe ranks of American investigators we may single out in particularthe eminent geologist Cope, who championed with much decision the ideaof the specific difference of _Homo neandertalensis_ (_primigenius_)and maintained a more direct descent of man from the fossil Lemuridae. In South America too, in Argentina, new life is stirring in thisdepartment of science. Ameghino in Buenos Ayres has awakened thefossil primates of the Pampas formation to new life; he even believesthat in his _Tetraprothomo_, represented by a femur, he has discovereda direct ancestor of man. Lehmann-Nitsche is working at the other sideof the gulf between apes and man, and he describes a remarkable firstcervical vertebra (atlas) from Monte Hermoso as belonging to a formwhich may bear the same relation to _Homo sapiens_ in South America as_Homo primigenius_ does in the Old World. After a minute investigationhe establishes a human species _Homo neogaeus_, while Ameghinoascribes this atlas vertebra to his _Tetraprothomo_. 

Thus throughout the whole scientific world there is arising a newlife, an eager endeavour to get nearer to Huxley's _problema maximum_, to penetrate more deeply into the origin of the human race. There areto-day very few experts in anatomy and zoology who deny the animaldescent of man in general. Religious considerations, old prejudices, the reluctance to accept man, who so far surpasses mentally all othercreatures, as descended from "soulless" animals, prevent a fewinvestigators from giving full adherence to the doctrine. But thereare very few of these who still postulate a special act of creationfor man. Although the majority of experts in anatomy and zoologyaccept unconditionally the descent of man from lower forms, there ismuch diversity of opinion among them in regard to the special line ofdescent. 

In trying to establish any special hypothesis of descent, whether bythe graphic method of drawing up genealogical trees or otherwise, letus always bear in mind Darwin's words[120] and use them as a criticalguiding line: "As we have no record of the lines of descent, thepedigree can be discovered only by observing the degrees ofresemblance between the beings which are to be classed. " Darwincarries this further by stating "that resemblances in severalunimportant structures, in useless and rudimentary organs, or not nowfunctionally active, or in an embryological condition, are by far themost serviceable for classification. "[121] It has also to beremembered that _numerous_ separate points of agreement are of muchgreater importance than the amount of similarity or dissimilarity in afew points. 

The hypotheses as to descent current at the present day may be dividedinto two main groups. The first group seeks for the roots of the humanrace not among any of the families of the apes--the anatomicallynearest forms--nor among their very similar but less specialisedancestral forms, the fossil representatives of which we can know onlyin part, but, setting the monkeys on one side, it seeks for them lowerdown among the fossil Eocene Pseudo-lemuridae or Lemuridae (Cope), oreven among the primitive pentadactylous Eocene forms, which mayeither have led directly to the evolution of man (Adloff), or havegiven rise to an ancestral form common to apes and men (Klaatsch, [122]Giuffrida-Ruggeri). The common ancestral form, from which man and apesare thus supposed to have arisen independently, may explain thenumerous resemblances which actually exist between them. That is tosay, all the characters upon which the great structural resemblancebetween apes and man depends must have been present in their commonancestor. Let us take an example of such a common character. The bonyexternal ear-passage is in general as highly developed in the lowerEastern monkeys and the anthropoid apes as in man. This charactermust, therefore, have already been present in the common primitiveform. In that case it is not easy to understand why the Westernmonkeys have not also inherited the character, instead of possessingonly a tympanic ring. But it becomes more intelligible if we assumethat forms with a primitive tympanic ring were the original type, andthat from these were evolved, on the one hand, the existing New Worldmonkeys with persistent tympanic ring, and on the other an ancestralform common to the lower Old World monkeys, the anthropoid apes andman. For man shares with these the character in question, and it isalso one of the "unimportant" characters required by Darwin. Thus wehave two divergent lines arising from the ancestral form, the Westernmonkeys (Platyrrhine) on the one hand, and an ancestral form common tothe lower Eastern monkeys, the anthropoid apes, and man, on the other. But considerations similar to those which showed it to be impossiblethat man should have developed from an ancestor common to him and themonkeys, yet outside of and parallel with these, may be urged alsoagainst the likelihood of a parallel evolution of the lower Easternmonkeys, the anthropoid apes, and man. The anthropoid apes have incommon with man many characters which are not present in the lowerOld World monkeys. These characters must therefore have been presentin the ancestral form common to the three groups. But here, again, itis difficult to understand why the lower Eastern monkeys should notalso have inherited these characters. As this is not the case, thereremains no alternative but to assume divergent evolution from anindifferent form. The lower Eastern monkeys are carrying on theevolution in one direction--I might almost say towards a blindalley--while anthropoids and men have struck out a progressive path, at first in common, which explains the many points of resemblancebetween them, without regarding man as derived directly from theanthropoids. Their many striking points of agreement indicate a commondescent, and cannot be explained as phenomena of convergence. 

I believe I have shown in the above sketch that a theory which derivesman directly from lower forms without regarding apes astransition-types leads _ad absurdum_. The close structuralrelationship between man and monkeys can only be understood if bothare brought into the same line of evolution. To trace man's line ofdescent directly back to the old Eocene mammals, alongside of, butwith no relation to these very similar forms, is to abandon the methodof exact comparison, which, as Darwin rightly recognised, alonejustifies us in drawing up genealogical trees on the basis ofresemblances and differences. The farther down we go the more does theground slip from beneath our feet. Even the Lemuridae show verynumerous divergent conditions, much more so the Eocene mammals(Creodonta, Condylarthra), the chief resemblance of which to manconsists in the possession of pentadactylous hands and feet! Thus thefarther course of the line of descent disappears in the darkness ofthe ancestry of the mammals. With just as much reason we might pass bythe Vertebrates altogether, and go back to the lower Invertebrates, but in that case it would be much easier to say that man has arisenindependently, and has evolved, without relation to any animals, fromthe lowest primitive form to his present isolated and dominantposition. But this would be to deny all value to classification, whichmust after all be the ultimate basis of a genealogical tree. We can, as Darwin rightly observed, only infer the line of descent from thedegree of resemblance between single forms. If we regard man asdirectly derived from primitive forms very far back, we have no way ofexplaining the many points of agreement between him and the monkeys ingeneral, and the anthropoid apes in particular. These must remain aninexplicable marvel. 

I have thus, I trust, shown that the first class of special theoriesof descent, which assumes that man has developed, parallel with themonkeys, but without relation to them, from very low primitive formscannot be upheld, because it fails to take into account the closestructural affinity of man and monkeys. I cannot but regard thishypothesis as lamentably retrograde, for it makes impossible anyapplication of the facts that have been discovered in the course ofthe anatomical and embryological study of man and monkeys, and indeedprejudges investigations of that class as pointless. The whole methodis perverted; an unjustifiable theory of descent is first formulatedwith the aid of the imagination, and then we are asked to declare thatall structural relations between man and monkeys, and between thedifferent groups of the latter, are valueless, --the fact being thatthey are the only true basis on which a genealogical tree can beconstructed. 

So much for this most modern method of classification, which hasprobably found adherents because it would deliver us from therelationship to apes which many people so much dislike. In contrast toit we have the second class of special hypotheses of descent, whichkeeps strictly to the nearest structural relationship. This is theonly basis that justifies the drawing up of a special hypothesis ofdescent. If this fundamental proposition be recognised, it will beadmitted that the doctrine of special descent upheld by Haeckel, andset forth in Darwin's _Descent of Man_, is still valid to-day. In thegenealogical tree, man's place is quite close to the anthropoid apes;these again have as their nearest relatives the lower Old Worldmonkeys, and their progenitors must be sought among the lessdifferentiated Platyrrhine monkeys, whose most important charactershave been handed on to the present day New World monkeys. How thedifferent genera are to be arranged within the general schemeindicated depends in the main on the classificatory value attributedto individual characters. This is particularly true in regard to_Pithecanthropus_, which I consider as the root of a branch which hassprung from the anthropoid ape root and has led up to man; the latterI have designated the family of the Hominidae. 

For the rest, there are, as we have said, various possible ways ofconstructing the narrower genealogy within the limits of this branchincluding men and apes, and these methods will probably continue tochange with the accumulation of new facts. Haeckel himself hasmodified his genealogical tree of the Primates in certain detailssince the publication of his _Generelle Morphologie_ in 1866, but itsgeneral basis remains the same. [123] All the special genealogicaltrees drawn up on the lines laid down by Haeckel and Darwin--and thatof Dubois may be specially mentioned--are based, in general, on theclose relationship of monkeys and men, although they may vary indetail. Various hypotheses have been formulated on these lines, withspecial reference to the evolution of man. _Pithecanthropus_ isregarded by some authorities as the direct ancestor of man, by othersas a side-track failure in the attempt at the evolution of man. Theproblem of the monophyletic or polyphyletic origin of the human racehas also been much discussed. Sergi[124] inclines towards theassumption of a polyphyletic origin of the three main races of man, the African primitive form of which has given rise also to thegorilla and chimpanzee, the Asiatic to the Orang, the Gibbon, and_Pithecanthropus_. Kollmann regards existing human races as derivedfrom small primitive races (pigmies), and considers that _Homoprimigenius_ must have arisen in a secondary and degenerative manner. 

But this is not the place, nor have I the space to criticise thevarious special theories of descent. One, however, must receiveparticular notice. According to Ameghino, the South American monkeys(_Pitheculites_) from the oldest Tertiary of the Pampas are the formsfrom which have arisen the existing American monkeys on the one hand, and on the other, the extinct South American Homunculidae, which arealso small forms. From these last, anthropoid apes and man have, hebelieves, been evolved. Among the progenitors of man, Ameghino reckonsthe form discovered by him (_Tetraprothomo_), from which a SouthAmerican primitive man, _Homo pampaeus_, might be directly evolved, while on the other hand all the lower Old World monkeys may havearisen from older fossil South American forms (Clenialitidae), thedistribution of which may be explained by the bridge formerly existingbetween South America and Africa, as may be the derivation of allexisting human races from _Homo pampaeus_. [125] The fossil formsdiscovered by Ameghino deserve the most minute investigation, as doesalso the fossil man from South America of which Lehmann-Nitsche[126]has made a thorough study. 

It is obvious that, notwithstanding the necessity for fitting man'sline of descent into the genealogical tree of the Primates, especiallythe apes, opinions in regard to it differ greatly in detail. Thiscould not be otherwise, since the different Primate forms, especiallythe fossile forms, are still far from being exhaustively known. Butone thing remains certain, --the idea of the close relationship betweenman and monkeys set forth in Darwin's _Descent of Man_. Only those whodeny the many points of agreement, the sole basis of classification, and thus of a natural genealogical tree, can look upon the position ofDarwin and Haeckel as antiquated, or as standing on an insufficientfoundation. For such a genealogical tree is nothing more than asummarised representation of what is known in regard to the degree ofresemblance between the different forms. 

Darwin's work in regard to the descent of man has not been surpassed;the more we immerse ourselves in the study of the structuralrelationships between apes and man, the more is our path illumined bythe clear light radiating from him, and through his calm anddeliberate investigation, based on a mass of material in theaccumulation of which he has never had an equal. Darwin's fame will bebound up for all time with the unprejudiced investigation of thequestion of all questions, the descent of the human race. 

FOOTNOTES:

[Footnote 75: _Life and Letters of Thomas Henry Huxley_, Vol. I. P. 171, London, 1900. ]

[Footnote 76: _Ibid. _, p. 363. ]

[Footnote 77: No italics in original. ]

[Footnote 78: _Life and Letters of Charles Darwin_, Vol. I. P. 93. ]

[Footnote 79: _Ibid. _ Vol. II. P. 263. ]

[Footnote 80: _Ibid. _ Vol. I. P. 94. ]

[Footnote 81: _Life and Letters_, Vol. III. P. 175. ]

[Footnote 82: _Ibid. _ Vol. II. P. 109. ]

[Footnote 83: _Ibid. _ Vol. III. P. 112. ]

[Footnote 84: _Ibid. _ Vol. I. Pp. 304-317. ]

[Footnote 85: _Life and Letters_, Vol. I. P. 309. ]

[Footnote 86: _Loc. Cit. _ p. 313. ]

[Footnote 87: _Ibid. _ Vol. II. P. 310. ]

[Footnote 88: _Ibid. _ Vol. III. P. 236. ["C. Ridley, " Mr. FrancisDarwin points out to me, should be H. N. Ridley. A. C. S. ]]

[Footnote 89: _Descent of Man_ (Popular Edit. , 1901), fig. 1, p. 14. ]

[Footnote 90: G. Schwalbe, "Das Darwin'sche Spitzohr beim menschlichenEmbryo, " _Anatom. Anzeiger_, 1889, pp. 176-189, and other papers. ]

[Footnote 91: _Descent of Man_, fig. 3, p. 24. ]

[Footnote 92: _Descent of man_, p. 6. ]

[Footnote 93: _Ibid. _ p. 54. ]

[Footnote 94: _Descent of Man_, p. 92. ]

[Footnote 95: _Ibid. _ p. 100. ]

[Footnote 96: _Life and letters_, Vol. II. P. 161, June 22, 1859. ]

[Footnote 97: _Ibid. _ Vol. III. P. 15, March 17, 1863. ]

[Footnote 98: _Descent of Man_, p. 132. ]

[Footnote 99: _Ibid. _ pp. 136, 137. ]

[Footnote 100: _Ibid. _ p. 143. ]

[Footnote 101: _Ibid. _ p. 193. ]

[Footnote 102: _Descent of Man_, p. 231. ]

[Footnote 103: _Descent of Man_, p. 308. ]

[Footnote 104: _Life and Letters_, Vol. II. P. 23. ]

[Footnote 105: _Loc. Cit. _ p. 39. ]

[Footnote 106: _Loc. Cit. _ (1856), p. 82. ]

[Footnote 107: _Ibid. _ Vol. III p. 159. ]

[Footnote 108: _Descent of Man_, p. 924. ]

[Footnote 109: "Die Hautfarbe des Menschen, " _Mitteilungen derAnthropologischen Gessellschaft in Wien_, Vol. XXXIV. Pp. 331-352. ]

[Footnote 110: _Ibid. _ p. 947. ]

[Footnote 111: _Descent of Man_, p. 240. ]

[Footnote 112: "Das geologische Alter der Pithecanthropus-Schichtenbei Trinil, Ost-Java. " _Neues Jahrb. F. Mineralogie_. Festband, 1907. ]

[Footnote 113: _Descent of Man_, p. 82. ]

[Footnote 114: "La race humaine de Néanderthal ou de Canstatt enBelgique. " _Arch. De Biologie_, VII. 1887. ]

[Footnote 115: Gorjanovič-Kramberger. _Der diluviale Mensch vanKrapina in Kroatien_, 1906. ]

[Footnote 116: _Studien zur Vorgeschichte des Menschen_, 1906, pp. 154ff. ]

[Footnote 117: "On the cranial and facial characters of the NeandertalRace. " _Trans. R. Soc. _ London, vol. 199, 1908, p. 281. ]

[Footnote 118: Since this essay was written Schoetensack hasdiscovered near Heidelberg and briefly described an exceedinglyinteresting lower jaw from rocks between the Pliocene and Diluvialbeds. This exhibits interesting differences from the forms of lowerjaw of _Homo primigenius_. (Schoetensack, _Der Unterkiefer des Homoheidelbergensis_, Leipzig, 1908. ) G. S. ]

[Footnote 119: _Life and Letters of Thomas Henry Huxley_, Vol. II. P. 394. ]

[Footnote 120: _Descent of Man_, p. 229. ]

[Footnote 121: _Loc. Cit. _]

[Footnote 122: Klaatsch in his last publications speaks in the mainonly of an ancestral form common to men and anthropoid apes. ]

[Footnote 123: Haeckels latest genealogical tree is to be found in hismost recent work, _Unsere Ahnenreihe_. Jena, 1908. ]

[Footnote 124: Sergi, G. _Europa_, 1908. ]

[Footnote 125: _See_ Ameghino's latest paper, "_Notas preliminariessobre el Tetraprothomo argentinus_, " etc. _Anales del Museo nacionalde Buenos Aires_, XVI. Pp. 107-242, 1907. ]

[Footnote 126: "Nouvelles recherches sur la formation pampéenne etl'homme fossile de la République Argentine. " _Rivista del Museo de laPlata_, T. XIV. Pp. 193-488. ]

V

CHARLES DARWIN AS AN ANTHROPOLOGIST

BY ERNST HAECKEL

_Professor of Zoology in the University of Jena_

The great advance that anthropology has made in the second half of thenineteenth century is due, in the first place, to Darwin's discoveryof the origin of man. No other problem in the whole field of researchis so momentous as that of "Man's place in nature, " which was justlydescribed by Huxley (1863) as the most fundamental of all questions. Yet the scientific solution of this problem was impossible until thetheory of descent had been established. 

It is now a hundred years since the great French biologist JeanLamarck published his _Philosophie Zoologique_. By a remarkablecoincidence the year in which that work was issued, 1809, was the yearof the birth of his most distinguished successor, Charles Darwin. Lamarck had already recognised that the descent of man from a seriesof other Vertebrates--that is, from a series of Ape-like Primates--wasessentially involved in the general theory of transformation which hehad erected on a broad inductive basis; and he had sufficientpenetration to detect the agencies that had been at work in theevolution of the erect bimanous man from the arboreal and quadrumanousape. He had, however, few empirical arguments to advance in support ofhis hypothesis, and it could not be established until the furtherdevelopment of the biological sciences--the founding of comparativeembryology by Baer (1828) and of the cell-theory by Schleiden andSchwann (1838), the advance of physiology under Johannes Müller(1833), and the enormous progress of palaeontology and comparativeanatomy between 1820 and 1860--provided this necessary foundation. Darwin was the first to coordinate the ample results of these lines ofresearch. With no less comprehensiveness than discrimination heconsolidated them as a basis of a modified theory of descent, andassociated with them his own theory of natural selection, which wetake to be distinctive of "Darwinism" in the stricter sense. Theilluminating truth of these cumulative arguments was so great in everybranch of biology that, in spite of the most vehement opposition, thebattle was won within a single decade, and Darwin secured the generaladmiration and recognition that had been denied to his forerunner, Lamarck, up to the hour of his death (1829). 

Before, however, we consider the momentous influence that Darwinismhas had in anthropology, we shall find it useful to glance at itshistory in the course of the last half century, and notice the varioustheories that have contributed to its advance. The first attempt togive extensive expression to the reform of biology by Darwin's workwill be found in my _Generelle Morphologie_ (1866)[127] which wasfollowed by a more popular treatment of the subject in my _NatürlicheSchöpfungsgeschichte_ (1868), [128] a compilation from the earlierwork. In the first volume of the _Generelle Morphologie_ I endeavouredto show the great importance of evolution in settling the fundamentalquestions of biological philosophy, especially in regard tocomparative anatomy. In the second volume I dealt broadly with theprinciple of evolution, distinguishing ontogeny and phylogeny as itstwo coordinate main branches, and associating the two in theBiogenetic Law. The Law may be formulated thus: "Ontogeny (embryologyor the development of the individual) is a concise and compressedrecapitulation of phylogeny (the palaeontological or genealogicalseries) conditioned by laws of heredity and adaptation. " The"Systematic introduction to general evolution, " with which the secondvolume of the _Generelle Morphologie_ opens, was the first attempt todraw up a natural system of organisms (in harmony with the principlesof Lamarck and Darwin) in the form of a hypothetical pedigree, and wasprovisionally set forth in eight genealogical tables. 

In the nineteenth chapter of the _Generelle Morphologie_--a part ofwhich has been republished, without any alteration, after a lapse offorty years--I made a critical study of Lamarck's theory of descentand of Darwin's theory of selection, and endeavoured to bring thecomplex phenomena of heredity and adaptation under definite laws forthe first time. Heredity I divided into conservative and progressive:adaptation into indirect (or potential) and direct (or actual). I thenfound it possible to give some explanation of the correlation of thetwo physiological functions in the struggle for life (selection), andto indicate the important laws of divergence (or differentiation) andcomplexity (or division of labor), which are the direct and inevitableoutcome of selection. Finally, I marked off dysteleology as thescience of the aimless (vestigial, abortive, atrophied, and useless)organs and parts of the body. In all this I worked from a strictlymonistic standpoint, and sought to explain all biological phenomena onthe mechanical and naturalistic lines that had long been recognised inthe study of inorganic nature. Then (1866), as now, being convinced ofthe unity of nature, the fundamental identity of the agencies at workin the inorganic and the organic worlds, I discarded vitalism, teleology, and all hypotheses of a mystic character. 

It was clear from the first that it was essential, in the monisticconception of evolution, to distinguish between the laws ofconservative and progressive heredity. Conservative heredity maintainsfrom generation to generation the enduring characters of the species. Each organism transmits to its descendants a part of the morphologicaland physiological qualities that it has received from its parents andancestors. On the other hand, progressive heredity brings newcharacters to the species--characters that were not found in precedinggenerations. Each organism may transmit to its offspring a part of themorphological and physiological features that it has itself acquired, by adaptation, in the course of its individual career, through the useor disuse of particular organs, the influence of environment, climate, nutrition, etc. At that time I gave the name of "progressive heredity"to this inheritance of acquired characters, as a short and convenientexpression, but have since changed the term to "transformativeheredity" (as distinguished from conservative). This term ispreferable, as inherited regressive modifications (degeneration, retrograde metamorphosis, etc. ) come under the same head. 

Transformative heredity--or the transmission of acquiredcharacters--is one of the most important principles in evolutionaryscience. Unless we admit it most of the facts of comparative anatomyand physiology are inexplicable. That was the conviction of Darwin noless than of Lamarck, of Spencer as well as Virchow, of Huxley as wellas Gegenbaur, indeed of the great majority of speculative biologists. This fundamental principle was for the first time called in questionand assailed in 1885 by August Weismann of Freiburg, the eminentzoologist to whom the theory of evolution owes a great deal ofvaluable support, and who has attained distinction by his extension ofthe theory of selection. In explanation of the phenomena of heredityhe introduced a new theory, the "theory of the continuity of thegerm-plasm. " According to him the living substance in all organismsconsists of two quite distinct kinds of plasm, somatic and germinal. The permanent germ-plasm, or the active substance of the twogerm-cells (egg-cell and sperm-cell), passes unchanged through aseries of generations, and is not affected by environmentalinfluences. The environment modifies only the soma-plasm, the organsand tissues of the body. The modifications that these parts undergothrough the influence of the environment or their own activity (useand habit), do not affect the germ-plasm, and cannot therefore betransmitted. 

This theory of the continuity of the germ-plasm has been expounded byWeismann during the last twenty-four years in a number of ablevolumes, and is regarded by many biologists, such as Mr. FrancisGalton, Sir E. Ray Lankester, and Professor J. Arthur Thomson (who hasrecently made a thorough-going defence of it in his important work_Heredity_), [129] as the most striking advance in evolutionaryscience. On the other hand, the theory has been rejected by HerbertSpencer, Sir W. Turner, Gegenbaur, Kölliker, Hertwig, and many others. For my part I have, with all respect for the distinguished Darwinian, contested the theory from the first, because its whole foundationseems to me erroneous, and its deductions do not seem to be in accordwith the main facts of comparative morphology and physiology. Weismann's theory in its entirety is a finely conceived molecularhypothesis, but it is devoid of empirical basis. The notion of theabsolute and permanent independence of the germ-plasm, asdistinguished from the soma-plasm, is purely speculative; as is alsothe theory of germinal selection. The determinants, ids, and idants, are purely hypothetical elements. The experiments that have beendevised to demonstrate their existence really prove nothing. 

It seems to me quite improper to describe this hypothetical structureas "Neodarwinism. " Darwin was just as convinced as Lamarck of thetransmission of acquired characters and its great importance in thescheme of evolution. I had the good fortune to visit Darwin at Downthree times and discuss with him the main principles of his system, and on each occasion we were fully agreed as to the incalculableimportance of what I may call transformative inheritance. It is onlyproper to point out that Weismann's theory of the germ-plasm is inexpress contradiction to the fundamental principles of Darwin andLamarck. Nor is it more acceptable in what one may call its"ultradarwinism"--the idea that the theory of selection explainseverything in the evolution of the organic world. This belief in the"omnipotence of natural selection" was not shared by Darwin himself. Assuredly, I regard it as of the utmost value, as the process ofnatural selection through the struggle for life affords an explanationof the mechanical origin of the adapted organisation. It solves thegreat problem: how could the finely adapted structure of the animal orplant body be formed unless it was built on a preconceived plan? Itthus enables us to dispense with the teleology of the metaphysicianand the dualist, and to set aside the old mythological and poeticlegends of creation. The idea had occurred in vague form to the greatEmpedocles 2000 years before the time of Darwin, but it was reservedfor modern research to give it ample expression. Nevertheless, naturalselection does not of itself give the solution of all our evolutionaryproblems. It has to be taken in conjunction with the transformism ofLamarck, with which it is in complete harmony. 

The monumental greatness of Charles Darwin, who surpasses every otherstudent of science in the nineteenth century by the loftiness of hismonistic conception of nature and the progressive influence of hisideas, is perhaps best seen in the fact that not one of his manysuccessors has succeeded in modifying his theory of descent in anyessential point or in discovering an entirely new standpoint in theinterpretation of the organic world. Neither Nägeli nor Weismann, neither De Vries nor Roux, has done this. Nägeli, in his_Mechanisch-Physiologische Theorie der Abstammungslehre_[130] which isto a great extent in agreement with Weismann, constructed a theory ofthe idioplasm, that represents it (like the germ-plasm) as developingcontinuously in a definite direction from internal causes. But hisinternal "principle of progress" is at the bottom just as teleologicalas the vital force of the Vitalists, and the micella structure of theidioplasm is just as hypothetical as the "dominant" structure of thegerm-plasm. In 1889 Moritz Wagner sought to explain the origin ofspecies by migration and isolation, and on that basis constructed aspecial "migration-theory. " This, however, is not out of harmony withthe theory of selection. It merely elevates one single factor in thetheory to a predominant position. Isolation is only a special case ofselection, as I had pointed out in the fifteenth chapter of my_Natural history of creation_. The "mutation-theory" of De Vries, [131]that would explain the origin of species by sudden and saltatoryvariations rather than by gradual modification, is regarded by manybotanists as a great step in advance, but it is generally rejected byzoologists. It affords no explanation of the facts of adaptation, andhas no causal value. 

Much more important than these theories is that of Wilhelm Roux[132]of "the struggle of parts within the organism, a supplementation ofthe theory of mechanical adaptation. " He explains the functionalautoformation of the purposive structure by a combination of Darwin'sprinciple of selection with Lamarck's idea of transformative heredity, and applies the two in conjunction to the facts of histology. He laysstress on the significance of functional adaptation, which I haddescribed in 1866, under the head of cumulative adaptation, as themost important factor in evolution. Pointing out its influence in thecell-life of the tissues, he puts "cellular selection" above "personalselection, " and shows how the finest conceivable adaptations in thestructure of the tissue may be brought about quite mechanically, without preconceived plan. This "mechanical teleology" is a valuableextension of Darwin's monistic principle of selection to the wholefield of cellular physiology and histology, and is wholly destructiveof dualistic vitalism. 

The most important advance that evolution has made since Darwin andthe most valuable amplification of his theory of selection is, in myopinion, the work of Richard Semon: _Die Mneme als erhaltendes Prinzipim Wechsel des organischen Geschehens_. [133] He offers a psychologicalexplanation of the facts of heredity by reducing them to a process of(unconscious) memory. The physiologist Ewald Hering had shown in 1870that memory must be regarded as a general function of organic matter, and that we are quite unable to explain the chief vital phenomena, especially those of reproduction and inheritance, unless we admit thisunconscious memory. In my essay _Die Perigenesis der Plastidule_[134]I elaborated this far-reaching idea, and applied the physicalprinciple of transmitted motion to the plastidules, or activemolecules of plasm. I concluded that "heredity is the memory of theplastidules, and variability their power of comprehension. " This"provisional attempt to give a mechanical explanation of theelementary processes of evolution" I afterwards extended by showingthat sensitiveness is (as Carl Nägeli, Ernst Mach, and Albrecht Rauexpress it) a general quality of matter. This form of panpsychismfinds its simplest expression in the "trinity of substance. "

To the two fundamental attributes that Spinoza ascribed tosubstance--Extension (matter as occupying space) and Cogitation(energy, force)--we now add the third fundamental quality of Psychoma(sensitiveness, soul). I further elaborated this trinitarianconception of substance in the nineteenth chapter of my _DieLebenswunder_ (1904), [135] and it seems to me well calculated toafford a monistic solution of many of the antitheses of philosophy. 

This important Mneme-theory of Semon and the luminous physiologicalexperiments and observations associated with it not only throwconsiderable light on transformative inheritance, but provide a soundphysiological foundation for the biogenetic law. I had endeavoured toshow in 1874, in the first chapter of my _Anthropogenie_, [136] thatthis fundamental law of organic evolution holds good generally, andthat there is everywhere a direct causal connection between ontogenyand phylogeny. "Phylogenesis is the mechanical cause of ontogenesis;"in other words, "The evolution of the stem or race is--in accordancewith the laws of heredity and adaptation--the real cause of all thechanges that appear, in a condensed form, in the development of theindividual organism from the ovum, in either the embryo or the larva. "

It is now fifty years since Charles Darwin pointed out, in thethirteenth chapter of his epoch-making _Origin of Species_, thefundamental importance of embryology in connection with his theory ofdescent:

"The leading facts in embryology, which are second to none inimportance, are explained on the principle of variations in the manydescendants from some one ancient progenitor, having appeared at a notvery early period of life, and having been inherited at acorresponding period. "[137]

He then shows that the striking resemblance of the embryos and larvaeof closely related animals, which in the mature stage belong to widelydifferent species and genera, can only be explained by their descentfrom a common progenitor. Fritz Müller made a closer study of theseimportant phenomena in the instructive instance of the Crustaceanlarva, as given in his able work _Für Darwin_[138] (1864). I then, in1872, extended the range so as to include all animals (with theexception of the unicellular Protozoa) and showed, by means of thetheory of the Gastraea, that all multicellular, tissue-forminganimals--all the Metazoa--develop in essentially the same way from theprimary germ-layers. 

I conceived the embryonic form, in which the whole structure consists ofonly two layers of cells, and is known as the gastrula, to be theontogenetic recapitulation, maintained by tenacious heredity, of aprimitive common progenitor of all the Metazoa, the Gastraea. At a laterdate (1895) Monticelli discovered that this conjectural ancestral form isstill preserved in certain primitive Coelenterata--Pemmatodiscus, Kunstleria, and the nearly-related Orthonectida. 

The general application of the biogenetic law to all classes ofanimals and plants has been proved in my _SystematischePhylogenie_. [139] It has, however, been frequently challenged, both bybotanists and zoologists, chiefly owing to the fact that many havefailed to distinguish its two essential elements, palingenesis andcenogenesis. As early as 1874 I had emphasised, in the first chapterof my _Evolution of Man_, the importance of discriminating carefullybetween these two sets of phenomena:

"In the evolutionary appreciation of the facts of embryology we musttake particular care to distinguish sharply and clearly between theprimary, palingenetic evolutionary processes and the secondary, cenogenetic processes. The palingenetic phenomena, or embryonic_recapitulations_, are due to heredity, to the transmission ofcharacters from one generation to another. They enable us to drawdirect inferences in regard to corresponding structures in thedevelopment of the species (e. G. The chorda or the branchial arches inall vertebrate embryos). The cenogenetic phenomena, on the other hand, or the embryonic _variations_, cannot be traced to inheritance from amature ancestor, but are due to the adaption of the embryo or thelarva to certain conditions of its individual development (e. G. Theamnion, the allantois, and the vitelline arteries in the embryos ofthe higher vertebrates). These cenogenetic phenomena are lateradditions; we must not infer from them that there were correspondingprocesses in the ancestral history, and hence they are apt tomislead. "

The fundamental importance of these facts of comparative anatomy, atavism, and the rudimentary organs, was pointed out by Darwin in thefirst part of his classic work, _The Descent of Man and Selection inRelation to Sex_ (1871). [140] In the "General summary and conclusion"(chap. Xxi. ) he was able to say, with perfect justice: "He who is notcontent to look, like a savage, at the phenomena of nature asdisconnected, cannot any longer believe that man is the work of aseparate act of creation. He will be forced to admit that the closeresemblance of the embryo of man to that, for instance, of a dog--theconstruction of his skull, limbs, and whole frame on the same planwith that of other mammals, independently of the uses to which theparts may be put--the occasional reappearance of various structures, for instance of several muscles, which man does not normally possess, but which are common to the Quadrumana--and a crowd of analogousfacts--all point in the plainest manner to the conclusion that man isthe co-descendant with other mammals of a common progenitor. "

These few lines of Darwin's have a greater scientific value thanhundreds of those so-called "anthropological treatises, " which givedetailed descriptions of single organs, or mathematical tables withseries of numbers and what are claimed to be "exact analyses, " but aredevoid of synoptic conclusions and a philosophical spirit. 

Charles Darwin is not generally recognised as a great anthropologist, nor does the school of modern anthropologists regard him as a leadingauthority. In Germany, especially, the great majority of the membersof the anthropological societies took up an attitude of hostility tohim from the very beginning of the controversy in 1860. _The Descentof Man_ was not merely rejected, but even the discussion of it wasforbidden on the ground that it was "unscientific. "

The centre of this inveterate hostility for thirty years--especiallyafter 1877--was Rudolph Virchow of Berlin, the leading investigatorin pathological anatomy, who did so much for the reform of medicine byhis establishment of cellular pathology in 1858. As a prominentrepresentative of "exact" or "descriptive" anthropology, and lacking abroad equipment in comparative anatomy and ontogeny, he was unable toaccept the theory of descent. In earlier years, and especially duringhis splendid period of activity at Würzburg (1848-1856), he had been aconsistent free-thinker, and had in a number of able articles(collected in his _Gesammelte Abhandlungen_)[141] upheld the unity ofhuman nature, the inseparability of body and spirit. In later years atBerlin, where he was more occupied with political work and sociology(especially after 1866), he abandoned the positive monistic positionfor one of agnosticism and scepticism, and made concessions to thedualistic dogma of a spiritual world apart from the material frame. 

In the course of a Scientific Congress at Munich in 1877 the conflictof these antithetic views of nature came into sharp relief. At thismemorable Congress I had undertaken to deliver the first address(September 18th) on the subject of "Modern evolution in relation tothe whole of science. " I maintained that Darwin's theory not onlysolved the great problem of the origin of species, but that itsimplications, especially in regard to the nature of man, threwconsiderable light on the whole of science, and on anthropology inparticular. The discovery of the real origin of man by evolution froma long series of mammal ancestors threw light on his place in naturein every respect, as Huxley had already shown in his excellentlectures of 1863. Just as all the organs and tissues of the human bodyhad originated from those of the nearest related mammals, certainape-like forms, so we were bound to conclude that his mental qualitiesalso had been derived from those of his extinct primate ancestor. 

This monistic view of the origin and nature of man, which is now admittedby nearly all who have the requisite acquaintance with biology, andapproach the subject without prejudice, encountered a sharp opposition atthat time. The opposition found its strongest expression in an address thatVirchow delivered at Munich four days afterwards (September 22nd), on "Thefreedom of science in the modern State. " He spoke of the theory ofevolution as an unproved hypothesis, and declared that it ought not to betaught in the schools, because it was dangerous to the State. "We mustnot, " he said, "teach that man has descended from the ape or any otheranimal. " When Darwin, usually so lenient in his judgment, read the Englishtranslation of Virchow's speech, he expressed his disapproval in strongterms. But the great authority that Virchow had--an authority well foundedin pathology and sociology--and his prestige as president of the GermanAnthropological Society, had the effect of preventing any member of theSociety from raising serious opposition to him for thirty years. Numbers ofjournals and treatises repeated his dogmatic statement: "It is quitecertain that man has descended neither from the ape nor from any otheranimal. " In this he persisted till his death in 1902. Since that time thewhole position of German anthropology has changed. The question is nolonger whether man was created by a distinct supernatural act or evolvedfrom other mammals, but to which line of the animal hierarchy we must lookfor the actual series of ancestors. The interested reader will find anaccount of this "battle of Munich" (1877) in my three Berlin lectures(April, 1905), _Der Kampf um die Entwickelungs-Gedanken_. [142]

The main points in our genealogical tree were clearly recognised byDarwin in the sixth chapter of the _Descent of Man_. Lowly organisedfishes, like the lancelot (Amphioxus), are descended from lowerinvertebrates resembling the larvae of an existing Tunicate(Appendicularia). From these primitive fishes were evolved higherfishes of the ganoid type and others of the type of Lepidosiren(Dipneusta). It is a very small step from these to the Amphibia:

"In the class of animals the steps are not difficult to conceive whichled from the ancient Monotremata to the ancient Marsupials; and fromthese to the early progenitors of the placental mammals. We may thusascend to the Lemuridae; and the interval is not very wide from theseto the Simiadae. The Simiadae then branched off into two great stems, the New World and Old World monkeys; and from the latter, at a remoteperiod, Man, the wonder and glory of the Universe, proceeded. "[143]

In these few lines Darwin clearly indicated the way in which we wereto conceive our ancestral series within the vertebrates. It is fullyconfirmed by all the arguments of comparative anatomy and embryology, of palaeontology and physiology; and all the research of thesubsequent forty years have gone to establish it. The deep interest ingeology which Darwin maintained throughout his life and his completeknowledge of palaeontology enabled him to grasp the fundamentalimportance of the palaeontological record more clearly thananthropologists and zoologists usually do. 

There has been much debate in subsequent decades whether Darwinhimself maintained that man was descended from the ape, and manywriters have sought to deny it. But the lines I have quoted _verbatim_from the conclusion of the sixth chapter of the _Descent of Man_(1871) leave no doubt that he was as firmly convinced of it as was hisgreat precursor Jean Lamarck in 1809. Moreover, Darwin adds, withparticular explicitness, in the "general summary and conclusion"(chap. Xxi. ) of that standard work:[144]

"By considering the embryological structure of man--the homologieswhich he presents with the lower animals, --the rudiments which heretains, --and the reversions to which he is liable, we can partlyrecall in imagination the former condition of our early progenitors;and can approximately place them in their proper place in thezoological series. We thus learn that man is descended from a hairy, tailed quadruped, probably arboreal in its habits, and an inhabitantof the Old World. This creature, if its whole structure had beenexamined by a naturalist, would have been classed amongst theQuadrumana, as surely as the still more ancient progenitor of the Oldand New World monkeys. "

These clear and definite lines leave no doubt that Darwin--so criticaland cautious in regard to important conclusions--was quite as firmlyconvinced of the descent of man from the apes (the Catarrhinae, inparticular) as Lamarck was in 1809 and Huxley in 1863. 

It is to be noted particularly that, in these and other observationson the subject, Darwin decidedly assumes the monophyletic origin ofthe mammals, including man. It is my own conviction that this is ofthe greatest importance. A number of difficult questions in regard tothe development of man, in respect of anatomy, physiology, psychology, and embryology, are easily settled if we do not merely extend our_progonotaxis_ to our nearest relatives, the anthropoid apes and thetailed monkeys from which these have descended, but go further backand find an ancestor in the group of the Lemuridae, and still furtherback to the Marsupials and Monotremata. The essential identity of allthe Mammals in point of anatomical structure and embryonicdevelopment--in spite of their astonishing differences in externalappearance and habits of life--is so palpably significant that modernzoologists are agreed in the hypothesis that they have all sprung froma common root, and that this root may be sought in the earlierPalaeozoic Amphibia. 

The fundamental importance of this comparative morphology of theMammals, as a sound basis of scientific anthropology, was recognisedjust before the beginning of the nineteenth century, when Lamarckfirst emphasised (1794) the division of the animal kingdom intoVertebrates and Invertebrates. Even thirteen years earlier (1781), when Goethe made a close study of the mammal skeleton in theAnatomical Institute at Jena, he was intensely interested to find thatthe composition of the skull was the same in man as in the othermammals. His discovery of the _os inter-maxillare_ in man (1784), which was contradicted by most of the anatomists of the time, and hisingenious "vertebral theory of the skull, " were the splendid fruit ofhis morphological studies. They remind us how Germany's greatestphilosopher and poet was for many years ardently absorbed in thecomparative anatomy of man and the mammals, and how he divined thattheir wonderful identity in structure was no mere superficialresemblance, but pointed to a deep internal connection. In my_Generelle Morphologie_ (1866), in which I published the firstattempts to construct phylogenetic trees, I have given a number ofremarkable theses of Goethe, which may be called "phyleticprophecies. " They justify us in regarding him as a precursor ofDarwin. 

In the ensuing forty years I have made many conscientious efforts topenetrate further along that line of anthropological research that wasopened up by Goethe, Lamarck, and Darwin. I have brought together the manyvaluable results that have constantly been reached in comparative anatomy, physiology, ontogeny, and palaeontology, and maintained the effort toreform the classification of animals and plants in an evolutionary sense. The first rough drafts of pedigrees that were published in the _GenerelleMorphologie_ have been improved time after time in the ten editions of my_Natürlich Schöpfungsgeschichte_ (1868-1902). [145] A sounded basis for myphyletic hypotheses, derived from a discriminating combination of the threegreat records--morphology, ontogeny, and palaeontology--was provided in thethree volumes of my _Systematische Phylogenie_[146] (1894 Protists andPlants, 1895 Vertebrates, 1896 Invertebrates). 

In my _Anthropogenie_[147] I endeavoured to employ all the knownfacts of comparative ontogeny (embryology) for the purpose ofcompleting my scheme of human phylogeny (evolution). I attempted tosketch the historical development of each organ of the body, beginningwith the most elementary structures in the germ-layers of theGastraea. At the same time I drew up a corrected statement of the mostimportant steps in the line of our ancestral series. 

At the fourth International Congress of Zoology at Cambridge (August26th, 1898) I delivered an address on "Our present knowledge of theDescent of Man. " It was translated into English, enriched with manyvaluable notes and additions, by my friend and pupil in earlier daysDr. Hans Gadow (Cambridge), and published under the title: _The LastLink: our present knowledge of the Descent of Man_[148] Thedetermination of the chief animal forms that occur in the line of ourancestry is there restricted to thirty types, and these aredistributed in six main groups. 

The first half of this "Progonotaxis hominis, " which has no supportfrom fossil evidence, comprises three groups: (i) Protista(unicellular organisms, 1-5): (ii) Invertebrate Metazoa (Coelenteria6-8, Vermalia 9-11): (iii) Monorrhine Vertebrates (Acrania 12-13, Cyclostoma 14-15). The second half, which is based on fossil records, also comprises three groups: (iv) Palaeozoic cold-blooded Craniota(Fishes 16-18, Amphibia 19, Reptiles 20): (v) Mesozoic Mammals(Monotrema 21, Marsupialia 22, Mallotheria 23): (vi) Cenozoic Primates(Lemuridae 24-25, Tailed Apes 26-27, Anthropomorpha 28-30). Animproved and enlarged edition of this hypothetic "Progonotaxishominis" was published in 1908, in my essay _Unsere Ahnenreihe_. [149]

If I have succeeded in furthering, in some degree, by theseanthropological works, the solution of the great problem of Man'splace in nature, and particularly in helping to trace the definitestages in our ancestral series, I owe the success, not merely to thevast progress that biology has made in the last half century, butlargely to the luminous example of the great investigators who haveapplied themselves to the problem, with so much assiduity and genius, for a century and a quarter--I mean Goethe and Lamarck, Gegenbaur andHuxley, but, above all, Charles Darwin. It was the great genius ofDarwin that first brought together that symmetrical temple ofscientific knowledge, the theory of descent. It was Darwin who put thecrown on the edifice by his theory of natural selection. Not untilthis broad inductive law was firmly established was it possible tovindicate the special conclusion, the descent of man from a series ofother Vertebrates. By his illuminating discovery Darwin did more foranthropology than thousands of those writers, who are morespecifically titled anthropologists, have done by their technicaltreatises. We may, indeed, say that it is not merely as an exactobserver and ingenious experimenter, but as a distinguishedanthropologist and far-seeing thinker, that Darwin takes his placeamong the greatest men of science of the nineteenth century. 

To appreciate fully the immortal merit of Darwin in connection withanthropology, we must remember that not only did his chief work, _TheOrigin of Species_, which opened up a new era in natural history in1859, sustain the most virulent and widespread opposition for alengthy period, but even thirty years later, when its principles weregenerally recognised and adopted, the application of them to man wasenergetically contested by many high scientific authorities. EvenAlfred Russel Wallace, who discovered the principle of naturalselection independently in 1858, did not concede that it wasapplicable to the higher mental and moral qualities of man. Dr. Wallace still holds a spiritualist and dualist view of the nature ofman, contending that he is composed of a material frame (descendedfrom the apes) and an immortal immaterial soul (infused by a higherpower). This dual conception, moreover, is still predominant in thewide circles of modern theology and metaphysics, and has the generaland influential adherence of the more conservative classes of society. 

In strict contradiction to this mystical dualism, which is generallyconnected with teleology and vitalism, Darwin always maintained thecomplete unity of human nature, and showed convincingly that thepsychological side of man was developed, in the same way as the body, from the less advanced soul of the anthropoid ape, and, at a stillmore remote period, from the cerebral functions of the oldervertebrates. The eighth chapter of the _Origin of Species_, which isdevoted to instinct, contains weighty evidence that the instincts ofanimals are subject, like all other vital processes, to the generallaws of historic development. The special instincts of particularspecies were formed by adaptation, and the modifications thus acquiredwere handed on to posterity by heredity; in their formation andpreservation natural selection plays the same part as in thetransformation of every other physiological function. The higher moralqualities of civilised man have been derived from the lower mentalfunctions of the uncultivated barbarians and savages, and these inturn from the social instincts of the mammals. This natural andmonistic psychology of Darwin's was afterwards more fully developed byhis friend George Romanes in his excellent works _Mental Evolution inAnimals_ and _Mental Evolution in Man_. [150]

Many valuable and most interesting contributions to this monisticpsychology of man were made by Darwin in his fine work on _The Descentof Man and Selection in Relation to Sex_, and again in hissupplementary work, _The Expression of the Emotions in Man andAnimals_. To understand the historical development of Darwin'santhropology one must read his life and the introduction to _TheDescent of Man_. From the moment that he was convinced of the truthof the principle of descent--that is to say, from his thirtieth year, in 1838--he recognised clearly that man could not be excluded from itsrange. He recognised as a logical necessity the important conclusionthat "man is the co-descendant with other species of some ancient, lower, and extinct form. " For many years he gathered notes andarguments in support of this thesis, and for the purpose of showingthe probable line of man's ancestry. But in the first edition of _TheOrigin of Species_ (1859) he restricted himself to the single line, that by this work "light would be thrown on the origin of man and hishistory. " In the fifty years that have elapsed since that time thescience of the origin and nature of man has made astonishing progress, and we are now fairly agreed in a monistic conception of nature thatregards the whole universe, including man, as a wonderful unity, governed by unalterable and eternal laws. In my philosophical book_Die Welträtsel_ (1899)[151] and in the supplementary volume _DieLebenswunder_ (1904)[152] I have endeavoured to show that this puremonism is securely established, and that the admission of theall-powerful rule of the same principle of evolution throughout theuniverse compels us to formulate a single supreme law--theall-embracing "Law of Substance, " or the united laws of the constancyof matter and the conservation of energy. We should never have reachedthis supreme general conception if Charles Darwin--a "monisticphilosopher" in the true sense of the word--had not prepared the wayby his theory of descent by natural selection, and crowned the greatwork of his life by the association of this theory with a naturalisticanthropology. 

FOOTNOTES:

[Footnote 127: _Generelle Morphologie der Organismen_, 2 vols. , Berlin, 1866. ]

[Footnote 128: Eng. Transl. ; _The History of Creation_, London, 1876. ]

[Footnote 129: London, 1908. ]

[Footnote 130: Munich, 1884. ]

[Footnote 131: _Die Mutationstheorie_, Leipzig, 1903. ]

[Footnote 132: _Der Kampf der Theile im Organismus_, Leipzig, 1881. ]

[Footnote 133: Leipzig, 1904. ]

[Footnote 134: Berlin, 1876. ]

[Footnote 135: _Wonders of Life_, London and New York, 1904. ]

[Footnote 136: Eng. Transl. ; _The Evolution of Man_, 2 vols. , London, 1879 and 1905. ]

[Footnote 137: _Origin of Species_ (6th edit. ), p. 396. ]

[Footnote 138: Eng. Transl. ; _Facts and Arguments for Darwin_, London, 1869. ]

[Footnote 139: 3 vols. , Berlin, 1894-96. ]

[Footnote 140: _Descent of Man_ (Popular Edit. ), p. 927. ]

[Footnote 141: _Gesammelte Abhandlungen zur wissenschaftlichenMedizin_, Berlin, 1856. ]

[Footnote 142: Eng. Transl. ; _Last Words on Evolution_, London, 1906. ]

[Footnote 143: _Descent of Man_, (Popular Edit. ), p. 255. ]

[Footnote 144: _Descent of Man_, p. 930. ]

[Footnote 145: Eng. Transl. ; _The History of Creation_, London, 1876. ]

[Footnote 146: Berlin, 1894-96. ]

[Footnote 147: Leipzig, 1874, 5th edit. 1905. Eng. Transl. ; _TheEvolution of Man_, London, 1905. ]

[Footnote 148: London, 1898. ]

[Footnote 149: _Festschrift zur 350-jährigen Jubelfeier der ThüringerUniversität Jena_. Jena. 1908. ]

[Footnote 150: London, 1885; 1888. ]

[Footnote 151: _The Riddle of the Universe_, London and New York, 1900. ]

[Footnote 152: _The Wonders of Life_, London and New York, 1904. ]

VI

MENTAL FACTORS IN EVOLUTION

BY C. LLOYD MORGAN, LLD. , F. R. S

In developing his conception of organic evolution Charles Darwin wasof necessity brought into contact with some of the problems of mentalevolution. In _The Origin of Species_ he devoted a chapter to "thediversities of instinct and of the other mental faculties in animalsof the same class. "[153] When he passed to the detailed considerationof _The Descent of Man_, it was part of his object to show "that thereis no fundamental difference between man and the higher mammals intheir mental faculties. "[154] "If no organic being excepting man, " hesaid, "had possessed any mental power, or if his powers had been of awholly different nature, from those of the lower animals, then weshould never have been able to convince ourselves that our highfaculties had been gradually developed. "[155] In his discussion of_The Expression of the Emotions_ it was important for his purpose"fully to recognise that actions readily become associated with otheractions and with various states of the mind. "[156] His hypothesis ofsexual selection is largely dependent upon the exercise of choice onthe part of the female and her preference for "not only the moreattractive but at the same time the more vigourous and viciousmales. "[157] Mental processes and physiological processes were forDarwin closely correlated; and he accepted the conclusion "that thenervous system not only regulates most of the existing functions ofthe body, but has indirectly influenced the progressive development ofvarious bodily structures and of certain mental qualities. "[158]

Throughout his treatment, mental evolution was for Darwin incidentalto and contributory to organic evolution. For specialised research incomparative and genetic psychology, as an independent field ofinvestigation, he had neither the time nor the requisite training. None the less his writings and the spirit of his work have exercised aprofound influence on this department of evolutionary thought. And, for those who follow Darwin's lead, mental evolution is still in ameasure subservient to organic evolution. Mental processes are theaccompaniments or concomitants of the functional activity of speciallydifferentiated parts of the organism. They are in some way dependenton physiological and physical conditions. But though they are notphysical in their nature, and though it is difficult or impossible toconceive that they are physical in their origin, they are, for Darwinand his followers, factors in the evolutionary process in its physicalor organic aspect. By the physiologist within his special andwell-defined universe of discourse they may be properly regarded asepiphenomena; but by the naturalist in his more catholic survey ofnature they cannot be so regarded, and were not so regarded by Darwin. Intelligence has contributed to evolution of which it is in a sense aproduct. 

The facts of observation or of inference which Darwin accepted arethese: Conscious experience accompanies some of the modes of animalbehaviour; it is concomitant with certain physiological processes;these processes are the outcome of development in the individual andevolution in the race; the accompanying mental processes undergo alike development. Into the subtle philosophical questions which ariseout of the naïve acceptance of such a creed it was not Darwin'sprovince to enter; "I have nothing to do, " he said, [159] "with theorigin of the mental powers, any more than I have with that of lifeitself. " He dealt with the natural history of organisms, including notonly their structure but their modes of behaviour; with the naturalhistory of the states of consciousness which accompany some of theiractions; and with the relation of behaviour to experience. We willendeavour to follow Darwin in his modesty and candour in making nopretence to give ultimate explanations. But we must note one of theimplications of this self-denying ordinance of science. Developmentand evolution imply continuity. For Darwin and his followers thecontinuity is organic through physical heredity. Apart fromspeculative hypothesis, legitimate enough in its proper place but hereout of court, we know nothing of continuity of mental evolution assuch: consciousness appears afresh in each succeeding generation. Hence it is that for those who follow Darwin's lead, mental evolutionis and must ever be, within his universe of discourse, subservient toorganic evolution. Only in so far as conscious experience, or itsneural correlate, effects some changes in organic structure can itinfluence the course of heredity; and conversely only in so far aschanges in organic structure are transmitted through heredity, ismental evolution rendered possible. Such is the logical outcome ofDarwin's teaching. 

Those who abide by the cardinal results of this teaching are bound toregard all behaviour as the expression of the functional activities ofthe living tissues of the organism, and all conscious experience ascorrelated with such activities. For the purposes of scientifictreatment, mental processes are one mode of expression of the samechanges of which the physiological processes accompanying behaviourare another mode of expression. This is simply accepted as a factwhich others may seek to explain. The behaviour itself is the adaptiveapplication of the energies of the organism; it is called forth bysome form of presentation or stimulation brought to bear on theorganism by the environment. This presentation is always an individualor personal matter. But in order that the organism may be fitted torespond to the presentation of the environment it must have undergonein some way a suitable preparation. According to the theory ofevolution this preparation is primarily racial and is transmittedthrough heredity. Darwin's main thesis was that the method ofpreparation is predominantly by natural selection. Subordinate toracial preparation, and always dependent thereon, is individual orpersonal preparation through some kind of acquisition; of which theguidance of behaviour through individually won experience is a typicalexample. We here introduce the mental factor because the facts seem tojustify the inference. Thus there are some modes of behaviour whichare wholly and solely dependent upon inherited racial preparation;there are other modes of behaviour which are also dependent, in partat least, on individual preparation. In the former case the behaviouris adaptive on the first occurrence of the appropriate presentation;in the latter case accommodation to circumstances is only reachedafter a greater or less amount of acquired organic modification ofstructure, often accompanied (as we assume) in the higher animals byacquired experience. Logically and biologically the two classes ofbehaviour are clearly distinguishable: but the analysis of complexcases of behaviour where the two factors coöperate, is difficult andrequires careful and critical study of life-history. 

The foundations of the mental life are laid in the consciousexperience that accompanies those modes of behaviour, dependententirely on racial preparation, which may broadly be described asinstinctive. In the eighth chapter of _The Origin of Species_ Darwinsays, [160] "I will not attempt any definition of instinct. .. . Everyone understands what is meant, when it is said that instinct impelsthe cuckoo to migrate and to lay her eggs in other birds' nests. Anaction, which we ourselves require experience to enable us to perform, when performed by an animal, more especially by a very young one, without experience, and when performed by many individuals in the sameway, without their knowing for what purpose it is performed, isusually said to be instinctive. " And in the summary at the close ofthe chapter he says, [161] "I have endeavoured briefly to show that themental qualities of our domestic animals vary, and that the variationsare inherited. Still more briefly I have attempted to show thatinstincts vary slightly in a state of nature. No one will dispute thatinstincts are of the highest importance to each animal. Thereforethere is no real difficulty, under changing conditions of life, innatural selection accumulating to any extent slight modifications ofinstinct which are in any way useful. In many cases habit or use anddisuse have probably come into play. "

Into the details of Darwin's treatment there is neither space nor needto enter. There are some ambiguous passages; but it may be said thatfor him, as for his followers to-day, instinctive behaviour is whollythe result of racial preparation transmitted through organic heredity. For the performance of the instinctive act no individual preparationunder the guidance of personal experience is necessary. It is truethat Darwin quotes with approval Huber's saying that "a little dose ofjudgment or reason often comes into play, even with animals low in thescale of nature. "[162] But we may fairly interpret his meaning to bethat in behaviour, which is commonly called instinctive, some elementof intelligent guidance is often combined. If this be conceded thestrictly instinctive performance (or part of the performance) is theoutcome of heredity and due to the direct transmission of parental orancestral aptitudes. Hence the instinctive response as such dependsentirely on how the nervous mechanism has been built up throughheredity; while intelligent behaviour, or the intelligent factor inbehaviour, depends also on how the nervous mechanism has been modifiedand moulded by use during its development and concurrently with thegrowth of individual experience in the customary situations of dailylife. Of course it is essential to the Darwinian thesis that what SirE. Ray Lankester has termed "educability, " not less than instinct, ishereditary. But it is also essential to the understanding of thisthesis that the differentiae of the hereditary factor should beclearly grasped. 

For Darwin there were two modes of racial preparation, (_1_) naturalselection, and (_2_) the establishment of individually acquired habit. He showed that instincts are subject to hereditary variation; he sawthat instincts are also subject to modification through acquisition inthe course of individual life. He believed that not only thevariations but also, to some extent, the modifications are inherited. He therefore held that some instincts (the greater number) are due tonatural selection but that others (less numerous) are due, or partlydue, to the inheritance of acquired habits. The latter involveLamarckian inheritance, which of late years has been the centre of somuch controversy. It is noteworthy however that Darwin laid especialemphasis on the fact that many of the most typical and also the mostcomplex instincts--those of neuter insects--do not admit of such aninterpretation. "I am surprised, " he says, [163] "that no one hashitherto advanced this demonstrative case of neuter insects, againstthe well-known doctrine of inherited habit, as advanced by Lamarck. "None the less Darwin admitted this doctrine as supplementary to thatwhich was more distinctively his own--for example in the case of theinstincts of domesticated animals. Still, even in such cases, "it maybe doubted, " he says, [164] "whether any one would have thought oftraining a dog to point, had not some one dog naturally shown atendency in this line . .. So that habit and some degree of selectionhave probably concurred in civilising by inheritance our dogs. " But inthe interpretation of the instincts of domesticated animals, a morerecently suggested hypothesis, that of organic selection, [165] may behelpful. According to this hypothesis any intelligent modification ofbehaviour which is subject to selection is probably coincident indirection with an inherited tendency to behave in this fashion. Hencein such behaviour there are two factors: (1) an incipient variation inthe line of such behaviour, and (2) an acquired modification by whichthe behaviour is carried further along the same line. Under naturalselection those organisms in which the two factors coöperate arelikely to survive. Under artificial selection they are deliberatelychosen out from among the rest. 

Organic selection has been termed a compromise between the morestrictly Darwinian and the Lamarckian principles of interpretation. But it is not in any sense a compromise. The principle ofinterpretation of that which is instinctive and hereditary is whollyDarwinian. It is true that some of the facts of observation reliedupon by Lamarckians are introduced. For Lamarckians however themodifications which are admittedly factors in survival, are regardedas the parents of inherited variations; for believers in organicselection they are only the foster-parents or nurses. It is becauseorganic selection is the direct outcome of and a natural extension ofDarwin's cardinal thesis that some reference to it here isjustifiable. The matter may be put with the utmost brevity as follows:(1) Variations (V) occur, some of which are in the direction ofincreased adaptation (+), others in the direction of decreasedadaptation (-). 

(2) Acquired modifications (M) also occur. Some of these are in thedirection of increased accommodation to circumstances (+), whileothers are in the direction of diminished accommodation (-). Fourmajor combinations are

 (_b_) + V with - M, (_c_) - V with + M, (_a_) + V with + M, (_d_) - V with - M. 

Of these (_d_) must inevitably be eliminated while (_a_) are selected. The predominant survival of (_a_) entails the survival of the adaptivevariations which are inherited. The contributory acquisitions (+ M)are not inherited; but there are none the less factors in determiningthe survival of the coincident variations. It is surely abundantlyclear that this is Darwinism and has no tincture of Lamarck'sessential principle, the inheritance of acquired characters. 

Whether Darwin himself would have accepted this interpretation of someat least of the evidence put forward by Lamarckians is unfortunately amatter of conjecture. The fact remains that in his interpretation ofinstinct and in allied questions he accepted the inheritance ofindividually acquired modifications of behaviour and structure. 

Darwin was chiefly concerned with instinct from the biological ratherthan from the psychological point of view. Indeed it must be confessedthat, from the latter standpoint, his conception of instinct as a"mental faculty" which "impels" an animal to the performance ofcertain actions, scarcely affords a satisfactory basis for genetictreatment. To carry out the spirit of Darwin's teaching it isnecessary to link more closely biological and psychological evolution. The first step towards this is to interpret the phenomena ofinstinctive behaviour in terms of stimulation and response. It may bewell to take a particular case. Swimming on the part of a duckling is, from the biological point of view, a typical example of instinctivebehaviour. Gently lower a recently hatched bird into water:coordinated movements of the limbs follow in rhythmical sequence. Thebehaviour is new to the individual though it is no doubt closelyrelated to that of walking, which is no less instinctive. There is agroup of stimuli afforded by the "presentation" which results frompartial immersion: upon this there follows as a complex response anapplication of the functional activities in swimming; the sequence ofadaptive application on the appropriate presentation is determined byracial preparation. We know, it is true, but little of thephysiological details of what takes place in the central nervoussystem; but in broad outline the nature of the organic mechanism andthe manner of its functioning may at least be provisionallyconjectured in the present state of physiological knowledge. Similarlyin the case of the pecking of newly-hatched chicks; there is a visualpresentation, there is probably a coöperating group of stimuli fromthe alimentary tract in need of food, there is an adaptive applicationof the activities in a definite mode of behaviour. Like data areafforded in a great number of cases of instinctive procedure, sometimes occurring very early in life, not infrequently deferreduntil the organism is more fully developed, but all of them dependentupon racial preparation. No doubt there is some range of variation inthe behaviour, just such variation as the theory of natural selectiondemands. But there can be no question that the higher animals inherita bodily organisation and a nervous system, the functional working ofwhich gives rise to those inherited modes of behaviour which aretermed instinctive. 

It is to be noted that the term "instinctive" is here employed in theadjectival form as a descriptive heading under which may be groupedmany and various modes of behaviour due to racial preparation. Wespeak of these as inherited; but in strictness what is transmittedthrough heredity is the complex of anatomical and physiologicalconditions under which, in appropriate circumstances, the organism sobehaves. So far the term "instinctive" has a restricted biologicalconnotation in terms of behaviour. But the connecting link betweenbiological evolution and psychological evolution is to be sought, --asDarwin fully realised, --in the phenomena of instinct, broadlyconsidered. The term "instinctive" has also a psychologicalconnotation. What is that connotation?

Let us take the case of the swimming duckling or the pecking chick, and fix our attention on the first instinctive performance. Grant thatjust as there is, strictly speaking, no inherited behaviour, but onlythe conditions which render such behaviour under appropriatecircumstances possible; so too there is no inherited experience, butonly the conditions which render such experience possible; then thecerebral conditions in both cases are the same. The biologicalbehaviour-complex, including the total stimulation and the totalresponse with the intervening or resultant processes in the sensorium, is accompanied by an experience-complex including the initialstimulation-consciousness and resulting response-consciousness. In theexperience-complex are comprised data which in psychological analysisare grouped under the headings of cognition, affective tone andconation. But the complex is probably experienced as an unanalysedwhole. If then we use the term "instinctive" so as to comprise allcongenital modes of behaviour which contribute to experience, we arein a position to grasp the view that the net result in consciousnessconstitutes what we may term the primary tissue of experience. To thedevelopment of this experience each instinctive act contributes. Thenature and manner of organisation of this primary tissue of experienceare dependent on inherited biological aptitudes; but they are from theoutset onwards subject to secondary development dependent on acquiredaptitudes. Biological values are supplemented by psychological valuesin terms of satisfaction or the reverse. 

In our study of instinct we have to select some particular phase ofanimal behaviour and isolate it so far as is possible from the life ofwhich it is a part. But the animal is a going concern, restlesslyactive in many ways. Many instinctive performances, as Darwin pointedout, [166] are serial in their nature. But the whole of active life isa serial and coordinated business. The particular instinctiveperformance is only an episode in a life-history, and every mode ofbehaviour is more or less closely correlated with other modes. Thiscoordination of behaviour is accompanied by a correlation of the modesof primary experience. We may classify the instinctive modes ofbehaviour and their accompanying modes of instinctive experience underas many heads as may be convenient for our purposes of interpretation, and label them instincts of self-preservation, of pugnacity, ofacquisition, the reproductive instincts, the parental instincts, andso forth. An instinct, in this sense of the term (for example theparental instinct), may be described as a specialised part of theprimary tissue of experience differentiated in relation to somedefinite biological end. Under such an instinct will fall a largenumber of particular and often well-defined modes of behaviour, eachwith its own peculiar mode of experience. 

It is no doubt exceedingly difficult as a matter of observation and ofinference securely based thereon to distinguish what is primary fromwhat is in part due to secondary acquisition--a fact which Darwinfully appreciated. Animals are educable in different degrees; butwhere they are educable they begin to profit by experience from thefirst. Only, therefore, on the occasion of the first instinctive actof a given type can the experience gained be regarded as _wholly_primary; all subsequent performance is liable to be in some degree, sometimes more, sometimes less, modified by the acquired dispositionwhich the initial behaviour engenders. But the early stages ofacquisition are always along the lines predetermined by instinctivedifferentiation. It is the task of comparative psychology todistinguish the primary tissue of experience from its secondary andacquired modifications. We cannot follow up the matter in furtherdetail. It must here suffice to suggest that this conception ofinstinct as a primary form of experience lends itself better tonatural history treatment than Darwin's conception of an impellingforce, and that it is in line with the main trend of Darwin's thought. 

In a characteristic work, --characteristic in wealth of detail, incloseness and fidelity of observation, in breadth of outlook, incandour and modesty, --Darwin dealt with _The Expression of theEmotions in Man and Animals_. Sir Charles Bell in his _Anatomy ofExpression_ had contended that many of man's facial muscles had beenspecially created for the sole purpose of being instrumental in theexpression of his emotions. Darwin claimed that a natural explanation, consistent with the doctrine of evolution, could in many cases begiven and would in other cases be afforded by an extension of theprinciples he advocated. "No doubt, " he said, [167] "as long as man andall other animals are viewed as independent creations, an effectualstop is put to our natural desire to investigate as far as possiblethe causes of Expression. By this doctrine, anything and everythingcan be equally well explained. .. . With mankind, some expressions . .. Can hardly be understood, except on the belief that man once existedin a much lower and animal-like condition. The community of certainexpressions in distinct though allied species . .. Is rendered somewhatmore intelligible, if we believe in their descent from a commonprogenitor. He who admits on general grounds that the structure andhabits of all animals have been gradually evolved, will look at thewhole subject of Expression in a new and interesting light. "

Darwin relied on three principles of explanation. "The first of theseprinciples is, that movements which are serviceable in gratifying somedesire, or in relieving some sensation, if often repeated, become sohabitual that they are performed, whether or not of any service, whenever the same desire or sensation is felt, even in a very weakdegree. "[168] The modes of expression which fall under this head havebecome instinctive through the hereditary transmission of acquiredhabit. "As far as we can judge, only a few expressive movements arelearnt by each individual; that is, were consciously and voluntarilyperformed during the early years of life for some definite object, orin imitation of others, and then became habitual. The far greaternumber of the movements of expression, and all the more importantones, are innate or inherited; and such cannot be said to depend onthe will of the individual. Nevertheless, all those included under ourfirst principle were at first voluntarily performed for a definiteobject, --namely, to escape some danger, to relieve some distress, orto gratify some desire. "[169]

"Our second principle is that of antithesis. The habit of voluntarilyperforming opposite movements under opposite impulses has becomefirmly established in us by the practice of our whole lives. Hence, ifcertain actions have been regularly performed, in accordance with ourfirst principle, under a certain frame of mind, there will be a strongand involuntary tendency to the performance of directly oppositeactions, whether or not these are of any use, under the excitement ofan opposite frame of mind. "[170] This principle of antithesis has notbeen widely accepted. Nor is Darwin's own position easy to grasp. 

"Our third principle, " he says, [171] "is the direct action of theexcited nervous system on the body, independently of the will, andindependently, in large part, of habit. Experience shows thatnerve-force is generated and set free whenever the cerebro-spinalsystem is excited. The direction which this nerve-force follows isnecessarily determined by the lines of connection between thenerve-cells, with each other and with various parts of the body. "

Lack of space prevents our following up the details of Darwin'streatment of expression. Whether we accept or do not accept his threeprinciples of explanation we must regard his work as a masterpiece ofdescriptive analysis, packed full of observations possessing lastingvalue. For a further development of the subject it is essential thatthe instinctive factors in expression should be more fullydistinguished from those which are individually acquired--a difficulttask--and that the instinctive factors should be rediscussed in thelight of modern doctrines of heredity, with a view to determiningwhether Lamarckian inheritance, on which Darwin so largely relied, isnecessary for an interpretation of the facts. 

The whole subject as Darwin realised is very complex. Even the term"expression" has a certain amount of ambiguity. When the emotion is infull flood, the animal fights, flees, or faints. Is this full-tideeffect to be regarded as expression; or are we to restrict the term tothe premonitory or residual effects--the bared canine when thefighting mood is being roused, the ruffled fur when reminiscentrepresentations of the object inducing anger cross the mind? Broadlyconsidered both should be included. The activity of premonitoryexpression as a means of communication was recognised by Darwin; hemight, perhaps, have emphasised it more strongly in dealing with thelower animals. Man so largely relies on a special means ofcommunication, that of language, that he sometimes fails to realisethat for animals with their keen powers of perception, and dependentas they are on such means of communication, the more strictlybiological means of expression are full of subtle suggestiveness. Manymodes of expression, otherwise useless, are signs of behaviour thatmay be anticipated, --signs which stimulate the appropriate attitude ofresponse. This would not, however, serve to account for the utility ofthe organic accompaniments--heart-affection, respiratory changes, vaso-motor effects and so forth, together with heightened musculartone, --on all of which Darwin lays stress[172] under his thirdprinciple. The biological value of all this is, however, of greatimportance, though Darwin was hardly in a position to take it fullyinto account. 

Having regard to the instinctive and hereditary factors of emotionalexpression we may ask whether Darwin's third principle does not alonesuffice as an explanation. Whether we admit or reject Lamarckianinheritance it would appear that all hereditary expression must be dueto pre-established connections within the central nervous system andto a transmitted provision for coordinated response under theappropriate stimulation. If this be so, Darwin's first and secondprinciples are subordinate and ancillary to the third, an expression, so far as it is instinctive or heredity, being "the direct result ofthe constitution of the nervous system. "

Darwin accepted the emotions themselves as hereditary or acquiredstates of mind and devoted his attention to their expression. Butthese emotions themselves are genetic products and as such dependenton organic conditions. It remained, therefore, for psychologists whoaccepted evolution and sought to build on biological foundations totrace the genesis of these modes of animal and human experience. Thesubject has been independently developed by Professors Lange andJames;[173] and some modification of their view is regarded by manyevolutionists as affording the best explanation of the facts. We mustfix our attention on the lower emotions, such as anger or fear, and ontheir first occurrence in the life of the individual organism. It is amatter of observation that if a group of young birds which have beenhatched in an incubator are frightened by an appropriate presentation, auditory or visual, they instinctively respond in special ways. If wespeak of this response as the expression, we find that there are manyfactors. There are certain visible modes of behaviour, crouching atonce, scattering and then crouching, remaining motionless, the bracedmuscles sustaining an attitude of arrest, and so forth, There are alsocertain visceral or organic effects, such as affections of the heartand respiration. These can be readily observed by taking the youngbird in the hand. Other effects cannot be readily observed; vaso-motorchanges, affections of the alimentary canal, the skin and so forth. Now the essence of the James-Lange view, as applied to thesecongenital effects, is that though we are justified in speaking ofthem as effects of the stimulation, we are not justified, withoutfurther evidence, in speaking of them as effects of the emotionalstate. May it not rather be that the emotion as a primary mode ofexperience is the concomitant of the net result of the organicsituation--the initial presentation, the instinctive mode ofbehaviour, the visceral disturbances?

According to this interpretation the primary tissue of experience ofthe emotional order, felt as an unanalysed complex, is generated bythe stimulation of the sensorium by afferent or incoming physiologicalimpulses from the special senses, from the organs concerned in theresponsive behaviour, from the viscere and vaso-motor system. 

Some psychologists, however, contend that the emotional experience isgenerated in the sensorium prior to, and not subsequent to, thebehaviour-response and the visceral disturbances. It is a direct andnot an indirect outcome of the presentation to the special senses. Bethis as it may, there is a growing tendency to bring into the closestpossible relation, or even to identify, instinct and emotion in theirprimary genesis. The central core of all such interpretations is thatinstinctive behaviour and experience, its emotional accompaniments, and its expression, are but different aspects of the outcome of thesame organic occurrences. Such emotions are, therefore, only adistinguishable aspect of the primary tissue of experience and exhibita like differentiation. Here again a biological foundation is laid fora psychological doctrine of the mental development of the individual. 

The intimate relation between emotion as a psychological mode ofexperience and expression as a group of organic conditions has animportant bearing on biological interpretation. The emotion, as thepsychological accompaniment of orderly disturbances in the centralnervous system, profoundly influences behaviour and often renders itmore vigourous and more effective. The utility of the emotions in thestruggle for existence can, therefore, scarcely be over-estimated. Just as keenness of perception has survival-value; just as it isobviously subject to variation; just as it must be enhanced undernatural selection, whether individually acquired increments areinherited or not; and just as its value lies not only in this or thatspecial perceptive act but in its importance for life as a whole; sothe vigourous effectiveness of activity has survival-value; it issubject to variation; it must be enhanced under natural selection; andits importance lies not only in particular modes of behaviour but inits value for life as a whole. If emotion and its expression as acongenital endowment are but different aspects of the same biologicaloccurrence; and if this is a powerful supplement to vigoureffectiveness and persistency of behaviour, it must on Darwin'sprinciples be subject to natural selection. 

If we include under the expression of the emotions not only thepremonitory symptoms of the initial phases of the organic and mentalstate, not only the signs or conditions of half-tide emotion, but thefull-tide manifestation of an emotion which dominates the situation, we are naturally led on to the consideration of many of the phenomenawhich are discussed under the head of sexual selection. The subject isdifficult and complex, and it was treated by Darwin with all thestrength he could summon to the task. It can only be dealt with herefrom a special point of view--that which may serve to illustrate theinfluence of certain mental factors on the course of evolution. Fromthis point of view too much stress can scarcely be laid on thedominance of emotion during the period of courtship and pairing in themore highly organised animals. It is a period of maximum vigour, maximum activity, and, correlated with special modes of behaviour andspecial organic and visceral accompaniments, a period also of maximumemotional excitement. The combats of males, their dances and aerialevolutions, their elaborate behaviour and display, or the flood ofsong in birds, are emotional expressions which are at any ratecoincident in time with sexual periodicity. From the combat of themales there follows on Darwin's principles the elimination of thosewhich are deficient in bodily vigour, deficient in special structures, offensive or protective, which contribute to success, deficient in theemotional supplement of which persistent and whole-hearted fighting isthe expression, and deficient in alertness and skill which are theoutcome of the psychological development of the powers of perception. Few biologists question that we have here a mode of selection of muchimportance, though its influence on psychological evolution oftenfails to receive its due emphasis. Mr. Wallace[174] regards it as "aform of natural selection"; "to it, " he says, "we must impute thedevelopment of the exceptional strength, size, and activity of themale, together with the possession of special offensive and defensiveweapons, and of all other characters which arise from the developmentof these or are correlated with them. " So far there is littledisagreement among the followers of Darwin--for Mr. Wallace, with finemagnanimity, has always preferred to be ranked as such, notwithstanding his right, on which a smaller man would haveconstantly insisted, to the claim of independent originator of thedoctrine of natural selection. So far with regard to sexual selectionDarwin and Mr. Wallace are agreed; so far and no farther. For Darwin, says Mr. Wallace, [175] "has extended the principle into a totallydifferent field of action, which has none of that character ofconstancy and of inevitable result that attaches to natural selection, including male rivalry; for by far the larger portion of thephenomena, which he endeavours to explain by the direct action ofsexual selection, can only be so explained on the hypothesis that theimmediate agency is female choice or preference. It is to this that heimputes the origin of all secondary sexual characters other thanweapons of offence and defence. .. . In this extension of sexualselection to include the action of female choice or preference, and inthe attempt to give to that choice such wide-reaching effects, I amunable to follow him more than a very little way. "

Into the details of Mr. Wallace's criticisms it is impossible to enterhere. We cannot discuss either the mode of origin of the variations instructure which have rendered secondary sexual characters possible orthe modes of selection other than sexual which have rendered them, within narrow limits, specifically constant. Mendelism and mutationtheories may have something to say on the subject when these theorieshave been more fully correlated with the basal principles ofselection. It is noteworthy that Mr. Wallace says:[176] "Besides theacquisition of weapons by the male for the purpose of fighting withother males, there are some other sexual characters which may havebeen produced by natural selection. Such are the various sounds andodours which are peculiar to the male, and which serve as a call tothe female or as an indication of his presence. These are evidently avaluable addition to the means of recognition of the two sexes, andare a further indication, that the pairing season has arrived; and theproduction, intensification, and differentiation of these sounds andodours are clearly within the power of natural selection. The sameremark will apply to the peculiar calls of birds, and even to thesinging of the males. " Why the same remark should not apply to theircolours and adornments is not obvious. What is obvious is that "meansof recognition" and "indication that the pairing season has arrived"are dependent on the perceptive powers of the female who recognisesand for whom the indication has meaning. The hypothesis of femalepreference, stripped of the aesthetic surplusage which ispsychologically both unnecessary and unproven, is really onlydifferent in degree from that which Mr. Wallace admits in principlewhen he says that it is probable that the female is pleased or excitedby the display. 

Let us for our present purpose leave on one side and regard as _subjudice_ the question whether the specific details of secondary sexualcharacters are the outcome of female choice. For us the question iswhether certain psychological accompaniments of the pairing situationhave influenced the course of evolution and whether thesepsychological accompaniments are themselves the outcome of evolution. As a matter of observation, specially differentiated modes ofbehaviour, often very elaborate, frequently requiring highly developedskill, and apparently highly charged with emotional tone, are theprecursors of pairing. They are generally confined to the males, whosefierce combats during the period of sexual activity are part of theemotional manifestation. It is inconceivable that they have nobiological meaning; and it is difficult to conceive that they have anyother biological end than to evoke in the generally more passivefemale the pairing impulse. They, are based on instinctive foundationsingrained in the nervous constitution through natural (or may we notsay sexual?) selection in virtue of their profound utility. They arecalled into play by a specialised presentation such as the sight orthe scent of the female at, or a little in advance of, a criticalperiod of the physiological rhythm. There is no necessity that themale should have any knowledge of the end to which his strenuousactivity leads up. In presence of the female there is an elaborateapplication of all the energies of behaviour, just because ages ofracial preparation have made him biologically and emotionally what heis--a functionally sexual male that must dance or sing or go throughhereditary movements of display, when the appropriate stimulationcomes. Of course after the first successful courtship his futurebehaviour will be in some degree modified by his previous experience. No doubt during his first courtship he is gaining the primary data ofa peculiarly rich experience, instinctive and emotional. But thebiological foundations of the behaviour of courtship are laid in thehereditary coordinations. It would seem that in some cases, not indeedin all, perhaps especially in those cases in which secondary sexualbehaviour is most highly evolved, --correlative with the ardour of themale is a certain amount of reluctance in the female. The pairing acton her part only takes place after prolonged stimulation, foraffording which the behaviour of male courtship is the requisitepresentation. The most vigourous, defiant and mettlesome male ispreferred just because he alone affords a contributory stimulationadequate to evoke the pairing impulse with its attendant emotionaltone. 

It is true that this places female preference or choice on a muchlower psychological plane than Darwin in some passages seems tocontemplate where, for example, he says that the female appreciatesthe display of the male and places to her credit a taste for thebeautiful. But Darwin himself distinctly states[177] that "it is notprobable that she consciously deliberates; but she is most excited orattracted by the most beautiful, or melodious, or gallant males. " Theview here put forward, which has been developed by Prof. Groos, [178]therefore seems to have Darwin's own sanction. The phenomena are notonly biological; there are psychological elements as well. One canhardly suppose that the female is unconscious of the male's presence;the final yielding must surely be accompanied by heightened emotionaltone. Whether we call it choice or not is merely a matter ofdefinition of terms. The behaviour is in part determined bysupplementary psychological values. Prof. Groos regards the coyness offemales as "a most efficient means of preventing the too early and toofrequent yielding to the sexual impulse. "[179] Be that as it may, itis, in any case, if we grant the facts, a means through which malesexual behaviour with all its biological and psychologicalimplications, is raised to a level otherwise perhaps unattainable bynatural means, while in the female it affords opportunities for thedevelopment in the individual and evolution in the race of what we mayfollow Darwin in calling appreciation, if we empty this word of theaesthetic implications which have gathered round it in the mental lifeof man. 

Regarded from this standpoint of sexual selection, broadly considered, has probably been of great importance. The psychologicalaccompaniments of the pairing situation have profoundly influenced thecourse of biological evolution and are themselves the outcome of thatevolution. 

Darwin makes only passing reference to those modes of behaviour inanimals which go by the name of play. "Nothing, " he says, [180] "ismore common than for animals to take pleasure in practising whateverinstinct they follow at other times for some real good. " This is oneof the very numerous cases in which a hint of the master has served tostimulate research in his disciples. It was left to Prof. Groos todevelop this subject on evolutionary lines and to elaborate in amasterly manner Darwin's suggestion. "The utility of play, " hesays, [181] "is incalculable. This utility consists in the practice andexercise it affords for some of the more important duties oflife, "--that is to say, for the performance of activities which willin adult life be essential to survival. He urges[182] that "the playof young animals has its origin in the fact that certain veryimportant instincts appear at a time when the animal does notseriously need them. " It is, however, questionable whether anyinstincts appear at a time when they are not needed. And it isquestionable whether the instinctive and emotional attitude of theplay-fight, to take one example, can be identified with those whichaccompany fighting in earnest, though no doubt they are closelyrelated and have some common factors. It is probable that play, aspreparatory behaviour, differs in biological detail (as it almostcertainly does in emotional attributes) from the earnest of after-lifeand that it has been evolved through differentiation and integrationof the primary tissue of experience, as a preparation through whichcertain essential modes of skill may be acquired--those animals inwhich the preparatory play-propensity was not inherited in due forceand requisite amount being subsequently eliminated in the struggle forexistence. In any case there is little question that Prof. Groos isright in basing the play-propensity on instinctive foundations. [183]None the less, as he contends, the essential biological value of playis that it is a means of training the educable nerve-tissue, ofdeveloping that part of the brain which is modified by experience andwhich thus acquires new characters, of elaborating the secondarytissue of experience on the predetermined lines of instinctivedifferentiation and thus furthering the psychological activities whichare included under the comprehensive term "intelligent. "

In _The Descent of Man_ Darwin dealt at some length with intelligenceand the higher mental faculties. [184] His object, he says, is to showthat there is no fundamental difference between man and the highermammals in their mental faculties; that these faculties are variableand the variations tend to be inherited; and that under naturalselection beneficial variations of all kinds will have been preservedand injurious ones eliminated. 

Darwin was too good an observer and too honest a man to minimise the"enormous difference" between the level of mental attainment ofcivilised man and that reached by any animal. His contention was thatthe difference, great as it is, is one of degree and not of kind. Herealised that, in the development of the mental faculties of man, newfactors in evolution have supervened--factors which play but asubordinate and subsidiary part in animal intelligence. Intercommunication by means of language, approbation and blame, andall that arises out of reflective thought, are but foreshadowed in themental life of animals. Still he contends that these may be explainedon the doctrine of evolution. He urges[185] "that man is variable inbody and mind; and that the variations are induced, either directly orindirectly, by the same general causes, and obey the same generallaws, as with the lower animals. " He correlates mental developmentwith the evolution of the brain. [186] "As the various mental facultiesgradually developed themselves, the brain would almost certainlybecome larger. No one, I presume, doubts that the large proportionwhich the size of man's brain bears to his body, compared to the sameproportion in the gorilla or orang, is closely connected with hishigher mental powers. " "With respect to the lower animals, " hesays, [187] "M. E. Lartet, [188] by comparing the crania of tertiary andrecent mammals belonging to the same groups, has come to theremarkable conclusion that the brain is generally larger and theconvolutions are more complex in the more recent form. "

Sir E. Ray Lankester has sought to express in the simplest terms theimplications of the increase in size of the cerebrum. "In what, " heasks, "does the advantage of a larger cerebral mass consist?" "Man, "he replies, "is born with fewer ready-made tricks of thenerve-centres--these performances of an inherited nervous mechanism sooften called by the ill-defined term 'instincts'--than are the monkeysor any other animal. Correlated with the absence of inheritedready-made mechanism, man has a greater capacity of developing in thecourse of his individual growth similar nervous mechanisms (similarto but not identical with those of 'instinct') than any otheranimal. .. . The power of being educated--'educability' as we may termit--is what man possesses in excess as compared with the apes. I thinkwe are justified in forming the hypothesis that it is this'educability' which is the correlative of the increased size of thecerebrum. " There has been natural selection of the more educableanimals, for "the character which we describe as 'educability' can betransmitted, it is a congenital character. But the _results_ ofeducation can _not_ be transmitted. In each generation they have to beacquired afresh, and with increased 'educability' they are morereadily acquired and a larger variety of them. .. . The fact is thatthere is no community between the mechanisms of instinct and themechanisms of intelligence, and that the latter are later in thehistory of the evolution of the brain than the former and can onlydevelop in proportion as the former become feeble and defective. "[189]

In this statement we have a good example of the further development ofviews which Darwin foreshadowed but did not thoroughly work out. Itstates the biological case clearly and tersely. Plasticity ofbehaviour in special accommodation to special circumstances is ofsurvival value; it depends upon acquired characters; it is correlatedwith increase in size and complexity of the cerebrum; under naturalselection therefore the larger and more complex cerebrum as the organof plastic behaviour has been the outcome of natural selection. Wehave thus the biological foundations for a further development ofgenetic psychology. 

There are diversities of opinion, as Darwin showed, with regard to therange of instinct in man and the higher animals as contrasted withlower types. Darwin himself said[190] that "Man, perhaps, has somewhatfewer instincts than those possessed by the animals which come next tohim in the series. " On the other hand, Prof. Wm. James says[191] thatman is probably the animal with most instincts. The true position isthat man and the higher animals have fewer complete and self-sufficinginstincts than those which stand lower in the scale of mentalevolution, but that they have an equally large or perhaps larger massof instinctive raw material which may furnish the stuff to beelaborated by intelligent processes. There is, perhaps, a greaterabundance of the primary tissue of experience to be refashioned andintegrated by secondary modification; there is probably the samedifferentiation in relation to the determining biological ends, butthere is at the outset less differentiation of the particular andspecific modes of behaviour. The specialised instinctive performancesand their concomitant experience-complexes are at the outset moreindefinite. Only through acquired connections, correlated withexperience, do they become definitely organised. 

The full working-out of the delicate and subtle relationship ofinstinct and educability--that is, of the hereditary and the acquiredfactors in the mental life--is the task which lies before genetic andcomparative psychology. They interact throughout the whole of life, and their interactions are very complex. No one can read the chaptersof _The Descent of Man_ which Darwin devotes to a consideration of themental characters of man and animals without noticing, on the onehand, how sedulous he is in his search for hereditary foundations, and, on the other hand, how fully he realises the importance ofacquired habits of mind. The fact that educability itself has innatetendencies--is in fact a partially differentiated educability--rendersthe unravelling of the factors of mental progress all the moredifficult. 

In his comparison of the mental powers of men and animals it wasessential that Darwin should lay stress on points of similarity ratherthan on points of difference. Seeking to establish a doctrine ofevolution, with its basal concept of continuity of process andcommunity of character, he was bound to render clear and to emphasisethe contention that the difference in mind between man and the higheranimals, great as it is, is one of degree and not of kind. To this endDarwin not only recorded a large number of valuable observations ofhis own, and collected a considerable body of information fromreliable sources, he presented the whole subject in a new light andshowed that a natural history of mind might be written and that thismethod of study offered a wide and rich field for investigation. Ofcourse those who regarded the study of mind only as a branch ofmetaphysics smiled at the philosophical ineptitude of the mere man ofscience. But the investigation, on natural history lines, has beenprosecuted with a large measure of success. Much indeed still remainsto be done; for special training is required, and the workers arestill few. Promise for the future is however afforded by the fact thatinvestigation is prosecuted on experimental lines and that somethinglike organised methods of research are taking form. There is now butlittle reliance on casual observations recorded by those who have notundergone the necessary discipline in these methods. There is alsosome change of emphasis in formulating conclusions. Now that thegeneral evolutionary thesis is fully and freely accepted by those whocarry on such researches, more stress is laid on the differentiationof the stages of evolutionary advance than on the fact of theirunderlying community of nature. The conceptual intelligence which isespecially characteristic of the higher mental procedure of man ismore firmly distinguished from the perceptual intelligence which heshares with the lower animals--distinguished now as a higher productof evolution, no longer as differing in origin or different in kind. Some progress has been made, on the one hand in rendering an accountof intelligent profiting by experience under the guidance of pleasureand pain in the perceptual field, on lines predetermined byinstinctive differentiation for biological ends, and on the other handin elucidating the method of conceptual thought employed, forexample, by the investigator himself in interpreting the perceptualexperience of the lower animals. 

Thus there is a growing tendency to realise more fully that there aretwo orders of educability--first an educability of the perceptualintelligence based on the biological foundation of instinct, andsecondly an educability of the conceptual intelligence whichrefashions and rearranges the data afforded by previous inheritanceand acquisition. It is in relation to this second and higher order ofeducability that the cerebrum of man shows so large an increase ofmass and a yet larger increase of effective surface through its richconvolutions. It is through educability of this order that the humanchild is brought intellectually and affectively into touch with theideal constructions by means of which man has endeavoured, with moreor less success, to reach an interpretation of nature, and to guidethe course of the further evolution of his race--ideal constructionswhich form part of man's environment. 

It formed no part of Darwin's purpose to consider, save in broadoutline, the methods, or to discuss in any fulness of detail theresults of the process by which a differentiation of the mentalfaculties of man from those of the lower animals has been broughtabout--a differentiation the existence of which he again and againacknowledges. His purpose was rather to show that, notwithstandingthis differentiation, there is basal community in kind. This must beremembered in considering his treatment of the biological foundationson which man's systems of ethics are built. He definitely stated thathe approached the subject "exclusively from the side of naturalhistory. "[192] His general conclusion is that the moral sense isfundamentally identical with the social instincts, which have beendeveloped for the good of the community; and he suggests that theconcept which thus enables us to interpret the biological ground-planof morals also enables us to frame a rational ideal of the moral end. "As the social instincts, " he says, [193] "both of man and the loweranimals have no doubt been developed by nearly the same steps, itwould be advisable, if found practicable, to use the same definitionin both cases, and to take as the standard of morality, the generalgood or welfare of the community, rather than the general happiness. "But the kind of community for the good of which the social instinctsof animals and primitive men were biologically developed may bedifferent from that which is the product of civilisation, as Darwin nodoubt realised. Darwin's contention was that conscience is a socialinstinct and has been evolved because it is useful to the tribe in thestruggle for existence against other tribes. One the other hand J. S. Mill urged that the moral feelings are not innate but acquired, andBain held the same view, believing that the moral sense is acquired byeach individual during his life-time. Darwin, who notes[194] theiropinion with his usual candour, adds that "on the general theory ofevolution this is at least extremely improbable. " It is impossible toenter into the question here: much turns on the exact connotation ofthe terms "conscience" and "moral sense, " and on the meaning we attachto the statement that the moral sense is fundamentally identical withthe social instincts. 

Presumably the majority of those who approach the subjects discussedin the third, fourth, and fifth chapters of _The Descent of Man_ inthe full conviction that mental phenomena, not less than organicphenomena, have a natural genesis, would, without hesitation, admitthat the intellectual and moral systems of civilised man are idealconstructions, the products of conceptual thought, and that as suchthey are, in their developed form, acquired. The moral sentiments arethe emotional analogues of highly developed concepts. This does nothowever imply that they are outside the range of natural historytreatment. Even though it may be desirable to differentiate the moralconduct of men from the social behaviour of animals (to which somesuch term as "pre-moral" or "quasi-moral" may be applied), still thefact remains that, as Darwin showed, there is abundant evidence of theoccurrence of such social behaviour--social behaviour which, evengranted that it is in large part intelligently acquired, and is itselfso far a product of educability, is of survival value. It makes forthat integration without which no social group could hold together andescape elimination. Furthermore, even if we grant that such behaviouris intelligently acquired, that is to say arises through themodification of hereditary instincts and emotions, the fact remainsthat only through these instinctive and emotional data is afforded theprimary tissue of the experience which is susceptible of suchmodification. 

Darwin sought to show, and succeeded in showing, that for theintellectual and moral life there are instinctive foundations which abiological treatment alone can disclose. It is true that he did not inall cases analytically distinguish the foundations from thesuperstructure. Even to-day we are scarcely in a position to do soadequately. But his treatment was of great value in giving an impetusto further research. This value indeed can scarcely be over-estimated. And when the natural history of the mental operations shall have beenwritten, the cardinal fact will stand forth, that the instinctive andemotional foundations are the outcome of biological evolution and havebeen ingrained in the race through natural selection. We shall moreclearly realise that educability itself is a product of naturalselection, though the specific results acquired through cerebralmodifications are not transmitted through heredity. It will, perhaps, also be realised that the instinctive foundations of social behaviourare, for us, somewhat out of date and have undergone but little changethroughout the progress of civilisation, because natural selection haslong since ceased to be the dominant factor in human progress. Thehistory of human progress has been mainly the history of man's highereducability, the products of which he has projected on to hisenvironment. This educability remains on the average what it was adozen generations ago; but the thought-woven tapestry of hissurroundings is refashioned and improved by each succeedinggeneration. Few men have in greater measure enriched thethought-environment with which it is the aim of education to bringeducable human beings into vital contact, than has Charles Darwin. Hisspecial field of work was the wide province of biology; but he didmuch to help us to realise that mental factors have contributed toorganic evolution and that in man, the highest product of Evolution, they have reached a position of unquestioned supremacy. 

FOOTNOTES:

[Footnote 153: _Origin of Species_ (6th edit. ), p. 205. ]

[Footnote 154: _Descent of man_ (2nd edit. 1888), Vol. I. P. 99;Popular edit. P. 99. ]

[Footnote 155: _Ibid. _ p. 99. ]

[Footnote 156: _The Expression of the Emotions_ (2nd edit. ), p. 32. ]

[Footnote 157: _Descent of Man_, Vol. II. P. 435. ]

[Footnote 158: _Ibid. _ 437, 438. ]

[Footnote 159: _Origin of Species_ (6th edit. ), p. 205. ]

[Footnote 160: _Origin of Species_ (6th edit. ), p. 205. ]

[Footnote 161: _Ibid. _ p. 233. ]

[Footnote 162: _Ibid. _ p. 205. ]

[Footnote 163: _Origin of Species_ (6th edit. ), p. 233. ]

[Footnote 164: _Origin of Species_, pp. 210, 211. ]

[Footnote 165: Independently suggested, on somewhat different lines, by Profs. J. Mark Baldwin, Henry F. Osborn and the writer. ]

[Footnote 166: _Origin of Species_ (6th edit. ), p. 206. ]

[Footnote 167: _Expression of the Emotions_, p. 13. The passage ishere somewhat condensed. ]

[Footnote 168: _Ibid. _ p. 368. ]

[Footnote 169: _Expression of the Emotions_, pp. 373, 374. ]

[Footnote 170: _Ibid. _ p. 368. ]

[Footnote 171: _Ibid. _ p. 369. ]

[Footnote 172: _Expression of the Emotions_, pp. 65 ff. ]

[Footnote 173: Cf. William James, _Principles of Psychology_, Vol. II. Chap. XXV, New York, 1890. ]

[Footnote 174: _Darwinism_, pp. 282, 283, London, 1889. ]

[Footnote 175: _Ibid. _ p. 283. ]

[Footnote 176: _Darwinism_, pp. 283, 284. ]

[Footnote 177: _Descent of Man_ (2nd edit. ), Vol. II. Pp. 136, 137;(Popular edit. ), pp. 642, 643. ]

[Footnote 178: _The Play of Animals_, p. 244, London, 1898. ]

[Footnote 179: _Ibid. _ p. 283. ]

[Footnote 180: _Descent of Man_, Vol. II. P. 60; (Popular edit. ), p. 566. ]

[Footnote 181: _The Play of Animals_, p. 76. ]

[Footnote 182: _Ibid. _ p. 75. ]

[Footnote 183: _The Play of Animals_ p. 24. ]

[Footnote 184: _Descent of Man_ (1st edit. ), Chaps. II, III, V; (2ndedit. ), Chaps. III, IV, V. ]

[Footnote 185: _Descent of Man_, Vol. I. Pp. 70, 71; (Popular edit. ), pp. 70, 71. ]

[Footnote 186: _Ibid. _ p. 81. ]

[Footnote 187: _Ibid. _ (Popular edit. ), p. 82. ]

[Footnote 188: _Comptes Rendus des Sciences_, June 1, 1868. ]

[Footnote 189: _Nature_, Vol. LXI. Pp. 624, 625 (1900). ]

[Footnote 190: _Descent of Man_, Vol. I. P. 100. ]

[Footnote 191: _Principles of Psychology_, Vol. II. P. 289. ]

[Footnote 192: _Descent of Man_, Vol. I. P. 149. ]

[Footnote 193: _Descent of Man_, p. 185. ]

[Footnote 194: _Ibid. _ p. 150 (footnote). ]

VII

THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY

BY H. HÖFFDING

_Professor of Philosophy in the University of Copenhagen_

I

It is difficult to draw a sharp line between philosophy and naturalscience. The naturalist who introduces a new principle, ordemonstrates a fact which throws a new light on existence, not onlyrenders an important service to philosophy but is himself aphilosopher in the broader sense of the word. The aim of philosophy inthe stricter sense is to attain points of view from which thefundamental phenomena and the principles of the special sciences canbe seen in their relative importance and connection. But philosophy inthis stricter sense has always been influenced by philosophy in thebroader sense. Greek philosophy came under the influence of logic andmathematics, modern philosophy under the influence of natural science. The name of Charles Darwin stands with those of Galileo, Newton, andRobert Mayer--names which denote new problems and great alterations inour conception of the universe. 

First of all we must lay stress on Darwin's own personality. His deep loveof truth, his indefatigable inquiry, his wide horizon, and his steadyself-criticism make him a scientific model, even if his results andtheories should eventually come to possess mainly an historical interest. In the intellectual domain the primary object is to reach high summitsfrom which wide surveys are possible, to reach them toiling honestlyupwards by the way of experience, and then not to turn dizzy when a summitis gained. Darwinians have sometimes turned dizzy, but Darwin never. He sawfrom the first the great importance of his hypothesis, not only because ofits solution of the old problem as to the value of the concept of species, not only because of the grand picture of natural evolution which itunrolls, but also because of the life and inspiration its method wouldimpart to the study of comparative anatomy, of instinct and of heredity, and finally because of the influence it would exert on the whole conceptionof existence. He wrote in his note-book in the year 1837: "My theory wouldgive zest to recent and fossil comparative anatomy; it would lead to thestudy of instinct, heredity, and mind-heredity, whole [of]metaphysics. "[195]

We can distinguish four main points in which Darwin's investigationspossess philosophical importance. 

The evolution hypothesis is much older than Darwin; it is, indeed, oneof the oldest guessings of human thought. In the eighteenth century iswas put forward by Diderot and Lamettrie and suggested by Kant (1786). As we shall see later, it was held also by several philosophers in thefirst half of the nineteenth century. In his preface to _The Origin ofSpecies_, Darwin mentions the naturalists who were his forerunners. But he has set forth the hypothesis of evolution in so energetic andthorough a manner that it perforce attracts the attention of allthoughtful men in a much higher degree than it did before thepublication of the _Origin_. 

And further, the importance of his teaching rests on the fact that he, much more than his predecessors, even than Lamarck, sought afoundation for his hypothesis in definite facts. Modern science beganby demanding--with Kepler and Newton--evidence of _varae causae_; thisdemand Darwin industriously set himself to satisfy--hence the wealthof material which he collected by his observations and hisexperiments. He not only revived an old hypothesis, but he saw thenecessity of verifying it by facts. Whether the special cause on whichhe founded the explanation of the origin of species--NaturalSelection--is sufficient, is now a subject of discussion. He himselfhad some doubt in regard to this question, and the criticisms whichare directed against his hypothesis hit Darwinism rather than Darwin. In his indefatigable search for empirical evidence he is a model evenfor his antagonists: he has compelled them to approach the problems oflife along other lines than those which were formerly followed. 

Whether the special cause to which Darwin appealed is sufficient or not, atleast to it is probably due the greater part of the influence which he hasexerted on the general trend of thought. "Struggle for existence" and"natural selection" are principles which have been applied, more or less, in every department of thought. Recent research, it is true, has discoveredgreater empirical discontinuity--leaps, "mutations"--whereas Darwinbelieved in the importance of small variations slowly accumulated. It hasalso been shown by the experimental method, which in recent biological workhas succeeded Darwin's more historical method, that types once constitutedpossess great permanence, the fluctuations being restricted within clearlydefined boundaries. The problem has become more precise, both as tovariation and as to heredity. The inner conditions of life have in bothrespects shown a greater independence than Darwin had supposed in histheory, though he always admitted that the cause of variation was to him agreat enigma, "a most perplexing problem, " and that the struggle for lifecould only occur where variation existed. But, at any rate, it was of thegreatest importance that Darwin gave a living impression of the strugglefor life which is everywhere going on, and to which even the highest formsof existence must be amenable. The philosophical importance of these ideasdoes not stand or fall with the answer to the question, whether naturalselection is a sufficient explanation of the origin of species or not ithas an independent, positive value for everyone who will observe life andreality with an unbiased mind. 

In accentuating the struggle for life Darwin stands as acharacteristically English thinker: he continues a train of ideaswhich Hobbes and Malthus had already begun. Moreover in his criticalviews as to the conception of species he had English forerunners; inthe middle ages Occam and Duns Scotus, in the eighteenth centuryBerkeley and Hume. In his moral philosophy, as we shall see later, heis an adherent of the school which is represented by Hutcheson, Homeand Adam Smith. Because he is no philosopher in the stricter sense ofthe term, it is of great interest to see that his attitude of mind isthat of the great thinkers of his nation. 

In considering Darwin's influence on philosophy we will begin with anexamination of the attitude of philosophy to the conception ofevolution at the time when _The Origin of Species_ appeared. We willthen examine the effects which the theory of evolution, and especiallythe idea of the struggle for life, has had, and naturally must have, on the discussion of philosophical problems. 

II

When _The Origin of Species_ appeared fifty years ago Romanticspeculation, Schelling's and Hegel's philosophy, still reigned on thecontinent, while in England Positivism, the philosophy of Comte andStuart Mill, represented the most important trend of thought. Germanspeculation had much to say on evolution, it even pretended to be aphilosophy of evolution. But then the word "evolution" was to be takenin an ideal, not in a real, sense. To speculative thought the formsand types of nature formed a system of ideas, within which any formcould lead us by continuous transitions to any other. It was aclassificatory system which was regarded as a divine world of thoughtor images, within which metamorphoses could go on--a conditioncomparable with that in the mind of the poet when one image followsanother with imperceptible changes. Goethe's ideas of evolution, asexpressed in his _Metamorphosen der Pflanzen und der Thiere_, belongto this category; it is, therefore, incorrect to call him a forerunnerof Darwin. Schelling and Hegel held the same idea; Hegel expresslyrejected the conception of a real evolution in time as coarse andmaterialistic. "Nature, " he says, "is to be considered as a _system ofstages_, the one necessarily arising from the other, and being thenearest truth of that from which it proceeds; but not in such a waythat the one is _naturally_ generated by the other; on the contrary[their connection lies] in the inner idea which is the ground ofnature. The _metamorphosis_ can be ascribed only to the notion assuch, because it alone is evolution. .. . It has been a clumsy idea inthe older as well as in the newer philosophy of nature, to regard thetransformation and the transition from one natural form and sphere toa higher as an outward and actual production. "[196]

The only one of the philosophers of Romanticism who believed in areal, historical evolution, a real production of new species, wasOken. [197] Danish philosophers, such as Treschow (1812) and Sibbern(1846), have also broached the idea of an historical evolution of allliving beings from the lowest to the highest. Schopenhauer'sphilosophy has a more realistic character than that of Schelling's andHegel's, his diametrical opposites, although he also belongs to theromantic school of thought. His philosophical and psychological viewswere greatly influenced by French naturalists and philosophers, especially by Cabanis and Lamarck. He praises the "ever memorableLamarck, " because he laid so much stress on the "will to live. " But herepudiates as a "wonderful error" the idea that the organs of animalsshould have reached their present perfection through a development intime, during the course of innumerable generations. It was, he said, aconsequence of the low standard of contemporary French philosophy, that Lamarck came to the idea of the construction of living beings intime through succession![198]

The positivistic stream of thought was not more in favour of a realevolution than was the Romantic school. Its aim was to adhere topositive facts: it looked with suspicion on far-reaching speculation. Comte laid great stress on the discontinuity found between thedifferent kingdoms of nature, as well as within each single kingdom. As he regarded as unscientific every attempt to reduce the number ofphysical forces, so he rejected entirely the hypothesis of Lamarckconcerning the evolution of species; the idea of species would in hiseyes absolutely lose its importance if a transition from species tospecies under the influence of conditions of life were admitted. Hisdisciples (Littré, Robin) continued to direct against Darwin thepolemics which their master had employed against Lamarck. Stuart Mill, who, in the theory of knowledge, represented the empirical orpositivistic movement in philosophy--like his English forerunners fromLocke to Hume--founded his theory of knowledge and morals on theexperience of the single individual. He sympathised with the theory ofthe original likeness of all individuals and derived theirdifferences, on which he practically and theoretically laid muchstress, from the influence both of experience and education, and, generally, of physical and social causes. He admitted an individualevolution, and, in the human species, an evolution based on socialprogress; but no physiological evolution of species. He was afraidthat the hypothesis of heredity would carry us back to the old theoryof "innate" ideas. 

Darwin was more empirical than Comte and Mill; experience disclosed tohim a deeper continuity than they could find; closer than before thenature and fate of the single individual were shown to be interwovenin the great web binding the life of the species with nature as awhole. And the continuity which so many idealistic philosophers couldfind only in the world of thought, he showed to be present in theworld of reality. 

III

Darwin's energetic renewal of the old idea of evolution has its chiefimportance in strengthening the conviction of this real continuity inthe world, of continuity in the series of form and events. It was agreat support for all those who were prepared to base their conceptionof life on scientific grounds. Together with the recently discoveredlaw of the conservation of energy, it helped to produce the greatrealistic movement which characterises the last third of thenineteenth century. After the decline of the Romantic movement peoplewished to have firmer ground under their feet and reality now asserteditself in a more emphatic manner than in the period of Romanticism. Itwas easy for Hegel to proclaim that "the real" was "the rational, " andthat "the rational" was "the real": reality itself existed for himonly in the interpretation of ideal reason, and if there was anythingwhich could not be merged in the higher unity of thought, then it wasonly an example of the "impotence of nature to hold to the idea. " Butnow concepts are to be founded on nature and not on any system ofcategories too confidently deduced _à priori_. The new devotion tonature had its recompense in itself, because the new points of viewmade us see that nature could indeed "hold to ideas, " though perhapsnot to those which we had cogitated beforehand. 

A most important question for philosophers to answer was whether thenew views were compatible with an idealistic conception of life andexistence. Some proclaimed that we have now no need of any philosophybeyond the principles of the conservation of matter and energy and theprinciple of natural evolution: existence should and could bedefinitely and completely explained by the laws of material nature. But abler thinkers saw that the thing was not so simple. They wereprepared to give the new views their just place and to examine whatalterations the old views must undergo in order to be brought intoharmony with the new data. 

The realistic character of Darwin's theory was shown not only in theidea of natural continuity, but also, and not least, in the idea ofthe cause whereby organic life advances step by step. This idea--theidea of the struggle for life--implied that nothing could persist, ifit had no power to maintain itself under the given conditions. Innervalue alone does not decide. Idealism was here put to its hardesttrial. In continuous evolution it could perhaps still find an analogyto the inner evolution of ideas in the mind; but in the demand forpower in order to struggle with outward conditions Realism seemed toannounce itself in its most brutal form. Every form of Idealism had toask itself seriously how it was going to "struggle for life" with thisnew Realism. 

We will now give a short account of the position which leadingthinkers in different countries have taken up in regard to thisquestion. 

I. Herbert Spencer was the philosopher whose mind was best prepared by hisown previous thinking to admit the theory of Darwin to a place in hisconception of the world. His criticism of the arguments which had been putforward against the hypothesis of Lamarck, showed that Spencer, as a youngman, was an adherent to the evolution idea. In his _Social Statics_ (1850)he applied this idea to human life and moral civilisation. In 1852 he wrotean essay on _The Development Hypothesis_, in which he definitely stated hisbelief that the differentiation of species, like the differentiation withina single organism, was the result of development. In the first edition ofhis _Psychology_ (1855) he took a step which put him in opposition to theolder English school (from Locke to Mill): he acknowledged "innate ideas"so far as to admit the tendency of acquired habits to be inherited in thecourse of generations, so that the nature and functions of the individualare only to be understood through its connection with the life of thespecies. In 1857, in his essay on _Progress_, he propounded the law ofdifferentiation as a general law of evolution, verified by examples fromall regions of experience, the evolution of species being only one of theseexamples. On the effect which the appearance of _The Origin of Species_ hadon his mind he writes in his _Autobiography_: "Up to that time . .. I heldthat the sole cause of organic evolution is the inheritance offunctionally-produced modifications. The _Origin of Species_ made it clearto me that I was wrong, and that the larger part of the facts cannot be dueto any such cause. .. . To have the theory of organic evolution justified wasof course to get further support for that theory of evolution at large withwhich . .. All my conceptions were bound up. "[199] Instead of themetaphorical expression "natural selection, " Spencer introduced the term"survival of the fittest, " which found favour with Darwin as well as withWallace. 

In working out his ideas of evolution, Spencer found thatdifferentiation was not the only form of evolution. In its simplestform evolution is mainly a concentration, previously scatteredelements being integrated and losing independent movement. Differentiation is only forthcoming when minor wholes arise within agreater whole. And the highest form of evolution is reached when thereis a harmony between concentration and differentiation, a harmonywhich Spencer calls equilibration and which he defines as a movingequilibrium. At the same time this definition enables him toillustrate the expression "survival of the fittest. " "Every livingorganism exhibits such a moving equilibrium--a balanced set offunctions constituting its life; and the overthrow of this balancedset of functions or moving equilibrium is what we call death. Someindividuals in a species are so constituted that their movingequilibria are less easily overthrown than those of otherindividuals; and these are the fittest which survive, or, in Mr. Darwin's language, they are the select which nature preserves. "[200]Not only in the domain of organic life, but in all domains, the summitof evolution is, according to Spencer, characterised by such aharmony--by a moving equilibrium. 

Spencer's analysis of the concept of evolution, based on a greatvariety of examples, has made this concept clearer and more definitethan before. It contains the three elements; integration, differentiation and equilibration. It is true that a concept which isto be valid for all domains of experience must have an abstractcharacter, and between the several domains there is, strictlyspeaking, only a relation of analogy. So there is only analogy betweenpsychical and physical evolution. But this is no serious objection, because general concepts do not express more than analogies betweenthe phenomena which they represent. Spencer takes his leading formsfrom the material world in defining evolution (in the simplest form)as integration of matter and dissipation of movement; but as he--notalways quite consistently[201]--assumed a correspondence of mind andmatter, he could very well give these terms an indirect importance forpsychical evolution. Spencer has always, in my opinion with fullright, repudiated the ascription of materialism. He is no more amaterialist than Spinoza. In his _Principles of Psychology_ (§ 63) heexpressed himself very clearly: "Though it seems easier to translateso-called matter into so-called spirit, than to translate so-calledspirit into so-called matter--which latter is indeed whollyimpossible--yet no translation can carry us beyond our symbols. " Thesewords lead us naturally to a group of thinkers whose starting-pointwas psychical evolution. But we have still one aspect of Spencer'sphilosophy to mention. 

Spencer founded his "laws of evolution" on an inductive basis, but hewas convinced that they could be deduced from the law of theconservation of energy. Such a deduction is, perhaps, possible for themore elementary forms of evolution, integration and differentiation;but it is not possible for the highest form, the equilibration, whichis a harmony of integration and differentiation. Spencer can no morededuce the necessity for the eventual appearance of "movingequilibria" of harmonious totalities than Hegel could guarantee the"higher unities" in which all contradictions should be reconciled. InSpencer's hands the theory of evolution acquired a more decidedlyoptimistic character than in Darwin's; but I shall deal later with therelation of Darwin's hypothesis to the opposition of optimism andpessimism. 

II. While the starting-point of Spencer was biological orcosmological, psychical evolution being conceived as in analogy withphysical, a group of eminent thinkers--in Germany Wundt, in FranceFouillée, in Italy Ardigò--took, each in his own manner, theirstarting-point in psychical evolution as an original fact and as atype of all evolution, the hypothesis of Darwin coming in as acorroboration and as a special example. They maintain the continuityof evolution; they find this character most prominent in psychicalevolution, and this is for them a motive to demand a correspondingcontinuity in the material, especially in the organic domain. 

To Wundt and Fouillée the concept of will is prominent. They see thetype of all evolution in the transformation of the life of will fromblind impulse to conscious choice; the theories of Lamarck and Darwinare used to support the view that there is in nature a tendency toevolution in steady reciprocity with external conditions. The strugglefor life is here only a secondary fact. Its apparent prominence isexplained by the circumstance that the influence of externalconditions is easily made out, while inner conditions can be verifiedonly through their effects. For Ardigò the evolution of thought wasthe starting-point and the type: in the evolution of a scientifichypothesis we see a progress from the indefinite (_indistinto_) to thedefinite (_distinto_), and this is a characteristic of all evolution, as Ardigò has pointed out in a series of works. The opposition between_indistinto_ and _distinto_ corresponds to Spencer's oppositionbetween homogeneity and heterogeneity. The hypothesis of the origin ofdifferences of species from more simple forms is a special example ofthe general law of evolution. 

In the views of Wundt and Fouillée we find the fundamental idea ofidealism psychical phenomena as expressions of the innermost nature ofexistence. They differ from the older Idealism in the great stresswhich they lay on evolution as a real, historical process which isgoing on through steady conflict with external conditions. TheRomantic dread of reality is broken. It is beyond doubt that Darwin'semphasis on the struggle for life as a necessary condition ofevolution has been a very important factor in carrying philosophy backto reality from the heaven of pure ideas. The philosophy of Ardigò, onthe other side, appears more as a continuation and deepening ofpositivism, though the Italian thinker arrived at his point of viewindependently of French-English positivism. The idea of continuousevolution is here maintained in opposition to Comte's and Mill'sphilosophy of discontinuity. From Wundt and Fouillée Ardigò differs inconceiving psychical evolution not as an immediate revelation of theinnermost nature of existence, but only as a single, though the mostaccessible example, of evolution. 

III. To the French philosophers Boutroux and Bergson, evolution properis continuous and qualitative, while outer experience and physicalscience give us fragments only, sporadic processes and mechanicalcombinations. To Bergson, in his recent work _L'Evolution Créatrice_, evolution consists in an _élan de vie_ which to our fragmentaryobservation and analytic reflexion appears as broken into a manifoldof elements and processes. The concept of matter in its scientificform is the result of this breaking asunder, essential for allscientific reflexion. In these conceptions the strongest oppositionbetween inner and outer conditions of evolution is expressed: in thedomain of internal conditions spontaneous development of qualitativeforms--in the domain of external conditions discontinuity andmechanical combination. 

We see, then, that the theory of evolution has influenced philosophyin a variety of forms. It has made idealistic thinkers revise theirrelation to the real world; it has led positivistic thinkers to find acloser connection between the facts on which they based their views;it has made us all open our eyes for new possibilities to arisethrough the _prima facie_ inexplicable "spontaneous" variations whichare the condition of all evolution. This last point is one of peculiarinterest. Deeper than speculative philosophy and mechanical sciencesaw in the days of their triumph, we catch sight of new streams, whosesources and laws we have still to discover. Most sharply does thisappear in the theory of mutation, which is only a strongeraccentuation of a main point in Darwinism. It is interesting to seethat an analogous problem comes into the foreground in physics throughthe discovery of radioactive phenomena, and in psychology through theassumption of psychical new formations (as held by Boutroux, WilliamJames and Bergson). From this side, Darwin's ideas, as well as theanalogous ideas in other domains, incite us to renewed examination ofour first principles, their rationality and their value. On the otherhand, his theory of the struggle for existence challenges us toexamine the conditions and discuss the outlook as to the persistenceof human life and society and of the values that belong to them. It isnot enough to hope (or fear?) the rising of new forms; we have also toinvestigate the possibility of upholding the forms and ideals whichhave hitherto been the bases of human life. Darwin has here given hisage the most earnest and most impressive lesson. This side of Darwin'stheory is of peculiar interest to some special philosophical problemsto which I now pass. 

IV

Among philosophical problems the problem of knowledge has in the lastcentury occupied a foremost place. It is natural, then, to ask howDarwin and the hypothesis whose most eminent representative he is, stand to this problem. 

Darwin started an hypothesis. But every hypothesis is won by inferencefrom certain presuppositions, and every inference is based on thegeneral principles of human thought. The evolution hypothesispresupposes, then, human thought and its principles. And not only theabstract logical principles are thus pre-supposed. The evolutionhypothesis purports to be not only a formal arrangement of phenomena, but to express also the law of a real process. It supposes, then, thatthe real data--all that in our knowledge which we do not produceourselves, but which we in the main simply receive--are subject tolaws which are at least analogous to the logical relations of ourthoughts; in other words, it assumes the validity of the principle ofcausality. If organic species could arise without cause there would beno use in framing hypotheses. Only if we assume the principle ofcausality, is there a problem to solve. 

Though Darwinism has had a great influence on philosophy considered asa striving after a scientific view of the world, yet here is a pointof view--the epistemological--where philosophy is not only independentbut reaches beyond any result of natural science. Perhaps it will besaid: the powers and functions of organic beings only persist (perhapsalso only arise) when they correspond sufficiently to the conditionsunder which the struggle of life is to go on. Human thought itself is, then, a variation (or a mutation) which has been able to persist andto survive. Is not, then, the problem of knowledge solved by theevolution hypothesis? Spencer had given an affirmative answer to thisquestion before the appearance of _The Origin of Species_. For theindividual, he said, there is an _à priori_, original, basis (or_Anlage_) for all mental life; but in the species all powers havedeveloped in reciprocity with extendal conditions. Knowledge is hereconsidered from the practical point of view, as a weapon in thestruggle for life, as an "organon" which has been continuously in usefor generations. In recent years the economic or pragmaticepistemology, as developed by Avenarius and Mach in Germany, and byJames in America, points in the same direction. Science, it is said, only maintains those principles and presuppositions which arenecessary to the simplest and clearest orientation be applied toexperience and to practical work, will successively be eliminated. 

In these views a striking and important application is made of theidea of struggle for life to the development of human thought. Thoughtmust, as all other things in the world, struggle for life. But thiswhole consideration belongs to psychology, not to the theory ofknowledge (epistemology), which is concerned only with the validity ofknowledge, not with its historical origin. Every hypothesis to explainthe origin of knowledge must submit to cross-examination by the theoryof knowledge, because it works with the fundamental forms andprinciples of human thought. We cannot go further back than theseforms and principles, which it is the aim of epistemology to ascertainand for which no further reason can be given. [202]

But there is another side of the problem which is, perhaps, of moreimportance and which epistemology generally overlooks. If newvariations can arise, not only in organic but perhaps also ininorganic nature, new tasks are placed before the human mind. Thequestion is, then, if it has forms in which there is room for the newmatter? We are here touching a possibility which the great master ofepistemology did not bring to light. Kant supposed confidently that noother matter of knowledge could stream forth from the dark sourcewhich he called "the thing-in-itself, " than such as could besynthesised in our existing forms of knowledge. He mentions thepossibility of other forms than the human, and warns us against thedogmatic assumption that the human conception of existence should beabsolutely adequate. But he seems to be quite sure that thething-in-itself works constantly, and consequently always gives usonly what our powers can master. This assumption was a consequence ofKant's rationalistic tendency, but one for which no warrant can begiven. Evolutionism and systematism are opposing tendencies which cannever be absolutely harmonised one with the other. Evolution may atany time break some form which the system-monger regards as finallyestablished. Darwin himself felt a great difference in looking atvariation as an evolutionist and as a systematist. When he was workingat his evolution theory, he was very glad to find variations; but theywere a hindrance to him when he worked as a systematist, in preparinghis work on Cirripedia. He says in a letter: "I had thought the sameparts of the same species more resemble (than they do anyhow inCirripedia) objects cast in the same mould. Systematic work would beeasy were it not for this confounded variation, which, however, ispleasant to me as a speculatist, though odious to me as asystematist. "[203] He could indeed be angry with variations even as anevolutionist; but then only because he could not explain them, notbecause he could not classify them. "If, as I must think, externalconditions produce little _direct_ effect, what the devil determineseach particular variation?"[204] What Darwin experienced in thisparticular domain holds good of all knowledge. All knowledge issystematic, in so far as it strives to put phenomena in quite definiterelations, one to another. But the systematisation can never becomplete. And here Darwin has contributed much to widen the world, forus. He has shown us forces and tendencies in nature which makeabsolute systems impossible, at the same time that they give us newobjects and problems. There is still a place for what Lessing called"the unceasing striving after truth, " while "absolute truth" (in thesense of a closed system) is unattainable so long as life andexperience are going on. 

There is here a special remark to be made. As we have seen above, recent research has shown that natural selection or struggle for lifeis no explanation of variations. Hugo de Vries distinguishes betweenpartial and embryonal variations, or between variations and mutations, only the last-named being heritable, and therefore of importance forthe origin of new species. But the existence of variations is not onlyof interest for the problem of the origin of species; it has also amore general interest. An individual does not lose its importance forknowledge, because its qualities are not heritable. On the contrary, in higher beings at least, individual peculiarities will become moreand more independent objects of interest. Knowledge takes account ofthe biographies not only of species, but also of individuals: it seeksto find the law of development of the single individual. [205] AsLeibnitz said long ago, individuality consists in the law of thechanges of a being: "La loi du changement fait l'individualité dechaque substance. " Here is a world which is almost new for science, which till now has mainly occupied itself with general laws and forms. But these are ultimately only means to understand the individualphenomena, in whose nature and history a manifold of laws and formsalways coöperate. The importance of this remark will appear in thesequel. 

V

To many people the Darwinian theory of natural selection or strugglefor existence seemed to change the whole conception of life, andparticularly all the conditions on which the validity of ethical ideasdepends. If only that has persistence which can be adapted to a givencondition, what will then be the fate of our ideals, of our standardsof good and evil? Blind force seems to reign, and the only thing thatcounts seems to be the most heedless use of power. Darwinism, it wassaid, has proclaimed brutality. No other difference seems permanentsave that between the sound, powerful and happy on the one side, thesick, feeble and unhappy on the other; and every attempt to alleviatethis difference seems to lead to general enervation. Some of those whointerpreted Darwinism in this manner felt an aesthetic delight incontemplating the heedlessness and energy of the great struggle forexistence and anticipated the realisation of a higher human type asthe outcome of it: so Nietzsche and his followers. Others recognisingthe same consequences in Darwinism regarded these as one of thestrongest objections against it; so Dühring and Kropotkin (in hisearlier works). 

This interpretation of Darwinism was frequent in the interval betweenthe two main works of Darwin--_The Origin of Species_ and _The Descentof Man_. But even during this interval it was evident to an attentivereader that Darwin himself did not found his standard of good and evilon the features of the life of nature he had emphasised so strongly. He did not justify the ways along which nature reached its ends; heonly pointed them out. The "real" was not to him, as to Hegel, onewith the "rational. " Darwin has, indeed, by his whole conception ofnature, rendered a great service to ethics in making the differencebetween the life of nature and the ethical life appear in so strong alight. The ethical problem could now be stated in a sharper form thanbefore. But this was not the first time that the idea of the strugglefor life was put in relation to the ethical problem. In theseventeenth century Thomas Hobbes gave the first impulse to the wholemodern discussion of ethical principles in his theory of _bellumomnium contra omnes_. Men, he taught, are in the state of natureenemies one of another, and they live either in fright or in the gloryof power. But it was not the opinion of Hobbes that this made ethicsimpossible. On the contrary, he found a standard for virtue and vicein the fact that some qualities and actions have a tendency to bringus out of the state of war and to secure peace, while other qualitieshave a contrary tendency. In the eighteenth century even ImmanuelKant's ideal ethics had--so far as can be seen--a similar origin. Shortly before the foundation of his definitive ethics, Kant wrote his_Idee zu einer allgemeinen Weltgeschichte_ (1784), where--in a waywhich reminds us of Hobbes, and is prophetic of Darwin--he describesthe forward-driving power of struggle in the human world. It is hereas with the struggle of the trees for light and air, through whichthey compete with one another in height. Anxiety about war can only beallayed by an ordinance which gives everyone his full liberty underacknowledgment of the equal liberty of others. And such ordinance andacknowledgment are also attributes of the content of the moral law, asKant proclaimed it in the year after the publication of his essay(1785). [206] Kant really came to his ethics by the way of evolution, though he afterwards disavowed it. Similarly the same line of thoughtmay be traced in Hegel though it has been disguised in the form ofspeculative dialectics. [207] And in Schopenhauer's theory of the blindwill to live and its abrogation by the ethical feeling, which isfounded on universal sympathy, we have a more individualistic form ofthe same idea. 

It was, then, not entirely a foreign point of view which Darwinintroduced into ethical thought, even if we take no account of thepoetical character of the word "struggle" and of the more directadaptation, through the use and non-use of power, which Darwin alsoemphasised. In _The Descent of Man_ he has devoted a specialchapter[208] to a discussion of the origin of the ethicalconsciousness. The characteristic expression of this consciousness hefound, just as Kant did, in the idea of "ought"; it was the origin ofthis new idea which should be explained. His hypothesis was that theethical "ought" has its origin in the social and parental instincts, which, as well as other instincts (e. G. The instinct ofself-preservation), lie deeper than pleasure and pain. In manyspecies, not least in the human species, these instincts are fosteredby natural selection; and when the powers of memory and comparison aredeveloped, so that single acts can be valued according to the claimsof the deep social instinct, then consciousness of duty and remorseare possible. Blind instinct has developed to conscious ethical will. 

As already stated, Darwin, as a moral philosopher belongs to theschool that was founded by Shaftesbury, and was afterwards representedby Hutcheson, Hume, Adam Smith, Comte and Spencer. His merit is, first, that he has given this tendency of thought a biologicalfoundation, and that he has stamped on it a doughty character inshowing that ethical ideas and sentiments, rightly conceived, areforces which are at work in the struggle for life. 

There are still many questions to solve. Not only does the ethicaldevelopment within the human species contain features stillunexplained;[209] but we are confronted by the great problem whetherafter all a genetic historical theory can be of decisive importancehere. To every consequent ethical consciousness there is a standard ofvalue, a primordial value which determines the single ethicaljudgments as their last presupposition, and the "rightness" of thisbasis, the "value" of this value can as little be discussed as the"rationality" of our logical principles. There is here revealed apossibility of ethical scepticism which evolutionistic ethics (as wellas intuitive or rationalistic ethics) has overlooked. No demonstrationcan show that the results of the ethical development are definitiveand universal. We meet here again with the important opposition ofsystematisation and evolution. There will, I think, always be an openquestion here, though comparative ethics, of which we have so far onlythe first attempts, can do much to throw light on it. 

It would carry us too far to discuss all the philosophical works onethics, which have been influenced directly or indirectly byevolutionism. I may, however, here refer to the book of C. M. Williams, _A Review of the Systems of Ethics founded on the Theory ofEvolution_, [210] in which, besides Darwin, the following authors arereviewed: Wallace, Haeckel, Spencer, Fiske, Rolph, Barratt, Stephen, Carneri, Höffding, Gizycki, Alexander, Rée. As works which criticiseevolutionistic ethics from an intuitive point of view and in aninstructive way, may be cited: Guyau, _La morale anglaisecontemporaine_, [211] and Sorley, _Ethics of Naturalism_. I will onlymention some interesting contributions to ethical discussion which canbe found in Darwinism besides the idea of struggle for life. 

The attention which Darwin has directed to variations has opened oureyes to the differences in human nature as well as in naturegenerally. There is here a fact of great importance for ethicalthought, no matter from what ultimate premiss it starts. Only from avery abstract point of view can different individuals be treated inthe same manner. The most eminent ethical thinkers, men such as JeremyBentham and Immanuel Kant, who discussed ethical questions from veryopposite standpoints, agreed in regarding all men as equal in respectof ethical endowment. In regard to Bentham, Leslie Stephen remarks:"He is determined to be thoroughly empirical, to take men as he foundthem. But his utilitarianism supposed that men's views of happinessand utility were uniform and clear, and that all that was wanted wasto show them the means by which their ends could be reached. "[212] AndKant supposed that every man would find the "categorical imperative"in his consciousness, when he came to sober reflexion, and that allwould have the same qualifications to follow it. But if continualvariations, great or small, are going on in human nature, it is theduty of ethics to make allowance for them, both in making claims, andin valuing what is done. A new set of ethical problems have theirorigin here. [213] It is an interesting fact that Stuart Mill's book_On Liberty_ appeared in the same year as _The Origin of Species_. Though Mill agreed with Bentham about the original equality of allmen's endowments, he regarded individual differences as a necessaryresult of physical and social influences, and he claimed that freeplay shall be allowed to differences of character so far as ispossible without injury to other men. It is a condition of individualand social progress that a man's mode of action should be determinedby his own character and not by tradition and custom, nor by abstractrules. This view was to be corroborated by the theory of Darwin. 

But here we have reached a point of view from which the criticism, which in recent years has often been directed against Darwin--thatsmall variations are of no importance in the struggle for life--is ofno weight. From an ethical standpoint, and particularly from theethical standpoint of Darwin himself, it is a duty to fosterindividual differences that can be valuable, even though they canneither be of service for physical preservation nor be physicallyinherited. The distinction between variation and mutation is herewithout importance. It is quite natural that biologists should beparticularly interested in such variations as can be inherited andproduce new species. But in the human world there is not only aphysical, but also a mental and social heredity. When an ideal humancharacter has taken form, then there is shaped a type, which throughimitation and influence can become an important factor in subsequentdevelopment, even if it cannot form a species in the biological senseof the word. Spiritually strong men often succumb in the physicalstruggle for life; but they can nevertheless be victorious through thetypical influence they exert, perhaps on very distant generations, ifthe remembrance of them is kept alive, be it in legendary or inhistorical form. Their very failure can show that a type has takenform which is maintained at all risks, a standard of life which isadhered to in spite of the strongest opposition. The question "to beor not to be" can be put from very different levels of being: it hastoo often been considered a consequence of Darwinism that thisquestion is only to be put from the lowest level. When a stage isreached, where ideal (ethical, intellectual, aesthetic) interests areconcerned, the struggle for life is a struggle for the preservation ofthis stage. The giving up of a higher standard of life is a sort ofdeath; for there is not only a physical, there is also a spiritual, death. 

VI

The Socratic character of Darwin's mind appears in his wariness indrawing the last consequences of his doctrine, in contrast both withthe audacious theories of so many of his followers and with theconsequences which his antagonists were busy in drawing. Though he, aswe have seen, saw from the beginning that his hypothesis wouldoccasion "a whole of metaphysics, " he was himself very reserved as tothe ultimate questions, and his answers to such questions wereextorted from him. 

As to the question of optimism and pessimism, Darwin held that thoughpain and suffering were very often the ways by which animals were ledto pursue that course of action which is most beneficial to thespecies, yet pleasurable feelings were the most habitual guides. "Wesee this in the pleasure from exertion, even occasionally from greatexertion of the body or mind, in the pleasure of our daily meals, andespecially in the pleasure derived from sociability, and from lovingour families. " But there was to him so much suffering in the worldthat it was a strong argument against the existence of an intelligentFirst Cause. [214]

It seems to me that Darwin was not so clear on another question, thatof the relation between improvement and adaptation. He wrote to Lyell:"When you contrast natural selection and 'improvement, ' you seemalways to overlook . .. That every step in the natural selection ofeach species implies improvement in that species _in relation to itscondition of life_. .. . Improvement implies, I suppose, _each formobtaining many parts or organs_, all excellently adapted for theirfunctions. " "All this, " he adds, "seems to me quite compatible withcertain forms fitted for simple conditions, remaining unaltered, orbeing, degraded. "[215] But the great question is, if the conditions oflife will in the long run favour "improvement" in the sense ofdifferentiation (or harmony of differentiation and integration). Manybeings are best adapted to their conditions of life if they have feworgans and few necessities. Pessimism would not only be theconsequence, if suffering outweighed happiness, but also if the mostelementary forms of happiness were predominant, or if there were atendency to reduce the standard of life to the simplest possible, thecontentment of inertia or stable equilibrium. There are animals whichare very highly differentiated and active in their young state, butlater lose their complex organisation and concentrate themselves onthe one function of nutrition. In the human world analogies to thissort of adaptation are not wanting. Young "idealists" very often endas old "Philistines. " Adaptation and progress are not the same. 

Another question of great importance in respect to human evolution is, whether there will be always a possibility for the existence of animpulse to progress, an impulse to make great claims on life, to beactive and to alter the conditions of life instead of adapting to themin a passive manner. Many people do not develop because they have toofew necessities, and because they have no power to imagine otherconditions of life than those under which they live. In his remarks on"the pleasure from exertion" Darwin has a point of contact with thepractical idealism of former times--with the ideas of Lessing andGoethe, of Condorcet and Fichte. The continual striving which was thecondition of salvation to Faust's soul, is also the condition ofsalvation to mankind. There is a holy fire which we ought to keepburning, if adaptation is really to be improvement. If, as I havetried to show in my _Philosophy of Religion_, the innermost core ofall religion is faith in the persistence of value in the world, and ifthe highest values express themselves in the cry "Excelsior!" then thecapital point is, that this cry should always be heard and followed. We have here a corollary of the theory of evolution in its applicationto human life. 

Darwin declared himself an agnostic, not only because he could notharmonise the large amount of suffering in the world with the idea ofa God as its first cause, but also because he "was aware that if weadmit a first cause, the mind still craves to know whence it came andhow it arose. "[216] He saw, as Kant had seen before him and expressedin his _Kritik der Urtheilskraft_, that we cannot accept either of theonly two possibilities which we are able to conceive: chance (or bruteforce) and design. Neither mechanism nor teleology can give anabsolute answer to ultimate questions. The universe, and especiallythe organic life in it, can neither be explained as a merecombination of absolute elements nor as the effect of a constructingthought. Darwin concluded, as Kant, and before him Spinoza, that theoppositions and distinctions which our experience presents, cannotsafely be regarded as valid for existence in itself. And, with Kantand Fichte, he found his stronghold in the conviction that man hassomething to do, even if he cannot solve all enigmas. "The safestconclusion seems to me that the whole subject is beyond the scope ofman's intellect; but man can do his duty. "[217]

Is this the last word of human thought? Does not the possibility, thatman can do his duty, suppose that the conditions of life allow ofcontinuous ethical striving, so that there is a certain harmonybetween cosmic order and human ideals? Darwin himself has shown howthe consciousness of duty can arise as a natural result of evolution. Moreover there are lines of evolution which have their end in ethicalidealism, in a kingdom of values, which must struggle for life as allthings in the world must do, but a kingdom which has its firmfoundation in reality. 

FOOTNOTES:

[Footnote 195: _Life and Letters of Charles Darwin_, Vol. I. P. 8. ]

[Footnote 196: _Encyclopädie der philosophischen Wissenschaften_ (4thedit. ), Berlin, 1845, § 249. ]

[Footnote 197: _Lehrbuch der Naturphilosophie_, Jena, 1809. ]

[Footnote 198: _Ueber den Willen in der Natur_ (2nd edit. ), Frankfurta. M. , 1854, pp. 41-43. ]

[Footnote 199: Spencer, _Autobiography_, Vol. II. P. 50, London andNew York, 1904. ]

[Footnote 200: _Autobiography_, Vol. II. P. 100. ]

[Footnote 201: Cf. My letter to him 1876, now printed in Duncan's_Life and Letters of Herbert Spencer_, p. 178. London, 1908. ]

[Footnote 202: The present writer, many years ago, in his _Psychology_(Copenhagen, 1882; Eng. Transl. London, 1891), criticised theevolutionistic treatment of the problem of knowledge from the Kantianpoint of view. ]

[Footnote 203: _Life and Letters_, Vol. II. P. 37. ]

[Footnote 204: _Ibid. _ p. 232. ]

[Footnote 205: The new science of Ecology occupies an intermediateposition between the biography of species and the biography ofindividuals. Compare _Congress of Arts and Science_, St. Louis, Vol. V. 1906 (The Reports of Drude and Robinson) and the work of mycolleague, E. Warming. ]

[Footnote 206: Cf. My _History of Modern Philosophy_ (Eng. Transl. London, 1900), I. Pp. 76-79. ]

[Footnote 207: "Herrschaft und Knechtschaft, " _Phönomenologie desGeistes_, IV. A. , Leiden, 1907. ]

[Footnote 208: _The Descent of Man_, Vol. I. Ch. Iii. ]

[Footnote 209: The works of Westermarck and Hobhouse throw new lighton many of these features. ]

[Footnote 210: New York and London, 1893. ]

[Footnote 211: Paris, 1879. ]

[Footnote 212: _English literature and society in the eighteenthcentury_, London, 1904, p. 187. ]

[Footnote 213: Cf. My paper, "The law of relativity in Ethics, "_International Journal of Ethics_, Vol. I. 1891, pp. 37-62. ]

[Footnote 214: _Life and Letters_, Vol. I. P. 310. ]

[Footnote 215: _Ibid. _ Vol. II. P. 177. ]

[Footnote 216: _Life and Letters_, Vol. 1. P. 306. ]

[Footnote 217: _Life and Letters_, p. 307. ]

VIII

THE INFLUENCE OF DARWIN UPON RELIGIOUS THOUGHT

BY P. N. WAGGETT, M. A. , S. S. J. E. 

I

The object of this paper is first to point out certain elements of theDarwinian influence upon Religious thought, and then to show reasonfor the conclusion that it has been, from a Christian point of view, satisfactory. I shall not proceed further to urge that the Christianapologetic in relation to biology has been successful. A variety ofopinions may be held on this question, without disturbing theconclusion that the movements of readjustment have been beneficial tothose who remain Christians, and this by making them more Christianand not only more liberal. The theologians may sometimes haveretreated, but there has been an advance of theology. I know that thisaccount incurs the charge of optimism. It is not the worst that couldbe made. The influence has been limited in personal range, unequal, even divergent, in operation, and accompanied by the appearance ofwaste and mischievous products. The estimate which follows requiresfor due balance a full development of many qualifying considerations. For this I lack space, but I must at least distinguish my view fromthe popular one that our difficulties about religion and naturalscience have come to an end. 

Concerning the older questions about origins--the origin of theworld, of species, of man, of reason, conscience, religion--a largemeasure of understanding has been reached by some thoughtful men. Butmeanwhile new questions have arisen, questions about conduct, regarding both the reality of morals and the rule of right action forindividuals and societies. And these problems, still far fromsolution, may also be traced to the influence of Darwin. For theyarise from the renewed attention to heredity, brought about by thesearch for the causes of variation, without which the study of theselection of variations has no sufficient basis. 

Even the existing understanding about origins is very far fromuniversal. On these points there were always thoughtful men who deniedthe necessity of conflict, and there are still thoughtful men who denythe possibility of a truce. 

It must further be remembered that the earlier discussion now, as Ihope to show, producing favourable results, created also for a timegrave damage, not only in the disturbance of faith and the loss ofmen--a loss not repaired by a change in the currents of debate--but inwhat I believe to be a still more serious respect. I mean theintroduction of a habit of facile and untested hypothesis in religiousas in other departments of thought. 

Darwin is not responsible for this, but he is in part the cause of it. Great ideas are dangerous guests in narrow minds; and thus it hashappened that Darwin--the most patient of scientific workers, in whomhypothesis waited upon research, or if it provisionally outstepped itdid so only with the most scrupulously careful acknowledgment--has ledsmaller and less conscientious men in natural science, in history, andin theology to an over-eager confidence in probable conjecture and aloose grip upon the facts of experience. It is not too much to saythat in many quarters the age of materialism was the leastmatter-of-fact age conceivable, and the age of science the age whichshowed least of the patient temper of inquiry. 

I have indicated, as shortly as I could, some losses and dangerswhich in a balanced account of Darwin's influence would be discussedat length. 

One other loss must be mentioned. It is a defect in our thought which, in some quarters, has by itself almost cancelled all the advantagessecured. I mean the exaggerated emphasis on uniformity or continuity;the unwillingness to rest any part of faith or of our practicalexpectation upon anything that from any point of view can be calledexceptional. The high degree of success reached by naturalists intracing, or reasonably conjecturing, the small beginnings of greatdifferences, has led the inconsiderate to believe that anything may intime become anything else. 

It is true that this exaggeration of the belief in uniformity hasproduced in turn its own perilous reaction. From refusing to believewhatever can be called exceptional, some have come to believe whatevercan be called wonderful. 

But, on the whole, the discontinuous or highly various character ofexperience received for many years too little deliberate attention. The conception of uniformity which is a necessity of scientificdescription has been taken for the substance of history. We haveaccepted a postulate of scientific method as if it were a conclusionof scientific demonstration. In the name of a generalisation which, however just on the lines of a particular method, is the prize of adifficult exploit of reflexion, we have discarded the directimpressions of experience; or, perhaps it is more true to say, we haveused for the criticism of alleged experiences a doctrine of uniformitywhich is only valid in the region of abstract science. For everyscience depends for its advance upon limitation of attention, upon theselection out of the whole content of consciousness of that part oraspect which is measurable by the method of the science. Accordinglythere is a science of life which rightly displays the unity underlyingall its manifestations. But there is another view of life, equallyvalid, and practically sometimes more important, which recognises theimmediate and lasting effect of crisis, difference, and revolution. Our ardour for the demonstration of uniformity of process and ofminute continuous change needs to be balanced by a recognition of thecatastrophic element in experience, and also by a recognition of theexceptional significance for us of events which may be perfectlyregular from an impersonal point of view. 

An exorbitant jealousy of miracle, revelation, and ultimate moraldistinctions has been imported from evolutionary science intoreligious thought. And it has been a damaging influence, because ithas taken men's attention from facts, and fixed them upon theories. 

II

With this acknowledgment of important drawbacks, requiring many wordsfor their proper description, I proceed to indicate certain results ofDarwin's doctrine which I believe to be in the long run whollybeneficial to Christian thought. These are:

The encouragement in theology of that evolutionary method ofobservation and study, which has shaped all modern research:

The recoil of Christian apologetics towards the ground of religiousexperience, a recoil produced by the pressure of scientific criticismupon other supports of faith:

The restatement, or the recovery of ancient forms of statement, of thedoctrines of Creation and of divine Design in Nature, consequent uponthe discussion of evolution and of natural selection as its guidingfactor. 

(1) The first of these is quite possibly the most important of all. Itwas well defined in a notable paper read by Dr. Gore, now Bishop ofBirmingham, to the Church Congress at Shrewsbury in 1896. We havelearnt a new caution both in ascribing and in denying significance toitems of evidence, in utterance or in event. There has been, as inart, a study of values, which secures perspective and solidity in ourrepresentation of facts. On the one hand, a given utterance or eventcannot be drawn into evidence as if all items were of equalconsequence, like sovereigns in a bag. The question whence and whithermust be asked, and the particular thing measured as part of a series. Thus measured it is not less truly important, but it may be importantin a lower degree. On the other hand, and for exactly the same reason, nothing that is real is unimportant. The "failures" are not meremistakes. We see them, in St. Augustine's words, as "scholar's faultswhich men praise in hope of fruit. "

We cannot safely trace the origin of the evolutionistic method to theinfluence of natural science. The view is tenable that theology ledthe way. Probably this is a case of alternate and reciprocal debt. Quite certainly the evolutionist method in theology, in Christianhistory and in the estimate of scripture, has received vastreinforcement from biology, in which evolution has been the everpresent and ever victorious conception. 

(2) The second effect named is the new willingness of Christianthinkers to take definite account of religious experience. This isrelated to Darwin through the general pressure upon religious faith ofscientific criticism. The great advance of our knowledge of organismshas been an important element in the general advance of science. Ithas acted, by the varied requirements of the theory of organisms, uponall other branches of natural inquiry, and it held for a long timethat leading place in public attention which is now occupied byspeculative physics. Consequently it contributed largely to ourpresent estimation of science as the supreme judge in all matters ofinquiry, [218] to the supposed destruction of mystery and thedisparagement of metaphysics which marked the last age, as well as tothe just recommendation of scientific method in branches of learningwhere the direct acquisitions of natural science had no place. 

Besides this, the new application of the idea of law and mechanicalregularity to the organic world seemed to rob faith of a kind ofrefuge. The romantics had, as Berthelot[219] shows, appealed to lifeto redress the judgments drawn from mechanism. Now, in Spencer, evolution gave us a vitalist mechanic or mechanical vitalism, and theappeal seemed cut off. We may return to this point later when weconsider evolution; at present I only endeavour to indicate thatgeneral pressure of scientific criticism which drove men of faith toseek the grounds of reassurance in a science of their own; in a methodof experiment, of observation, of hypothesis checked by known facts. It is impossible for me to do more than glance across the threshold ofthis subject. But it is necessary to say that the method is in anelementary stage of revival. The imposing success that belongs tonatural science is absent: we fall short of the unchallengeableunanimity of the Biologists on fundamentals. The experimental methodwith its sure repetitions cannot be applied to our subject-matter. Butwe have something like the observational method of palaeontology andgeographical distribution; and in biology there are still men whothink that the large examination of varieties by way of geography andthe search of strata is as truly scientific, uses as genuinely thelogical method of difference, and is as fruitful in sure conclusionsas the quasi-chemical analysis of Mendelian laboratory work, of whichlast I desire to express my humble admiration. Religion also has itsobservational work in the larger and possibly more arduous manner. 

But the scientific work in religion makes its way through difficultiesand dangers. We are far from having found the formula of itscombination with the historical elements of our apologetic. It isexposed, therefore, to a damaging fire not only from unspiritualistpsychology and pathology but also from the side of scholastic dogma. It is hard to admit on equal terms a partner to the old undivided ruleof books and learning. With Charles Lamb, we cry in some distress, "must knowledge come to me, if it come at all, by some awkwardexperiment of intuition, and no longer by this familiar process ofreading?"[220] and we are answered that the old process has animperishable value, only we have not yet made clear its connectionwith other contributions. And all the work is young, liable to bedrawn into unprofitable excursions, side-tracked by self-deceit andpretence; and it fatally attracts, like the older mysticism, thecuriosity and the expository powers of those least in sympathy withit, ready writers who, with all the air of extended research, havebeen content with narrow grounds for induction. There is a danger, besides, which accompanies even the most genuine work of this scienceand must be provided against by all its serious students. I mean thedanger of unbalanced introspection both for individuals and forsocieties; of a preoccupation comparable to our modern socialpreoccupation with bodily health; of reflexion upon mental states notaccompanied by exercise and growth of the mental powers; the danger ofcontemplating will and neglecting work, of analysing conviction andnot criticising evidence. 

Still, in spite of dangers and mistakes, the work remains full ofhopeful indications, and, in the best examples, [221] it is trulyscientific in its determination to know the very truth, to tell whatwe think, not what we think we ought to think, [222] truly scientificin its employment of hypothesis and verification, and in growingconviction of the reality of its subject-matter through the repeatedvictories of a mastery which advances, like science, in the Baconianroad of obedience. It is reasonable to hope that progress in thisrespect will be more rapid and sure when religious study enlists moremen affected by scientific desire and endowed with scientificcapacity. 

The class of investigating minds is a small one, possibly even smallerthan that of reflecting minds. Very few persons at any period are ableto find out anything whatever. There are few observers, fewdiscoverers, few who even wish to discover truth. In how manysocieties the problems of philology which face every person who speaksEnglish are left unattempted! And if the inquiring or the successfullyinquiring class of minds is small, much smaller, of course, is theclass of those possessing the scientific aptitude in an eminentdegree. During the last age this most distinguished class was to avery great extent absorbed in the study of phenomena, a study whichhad fallen into arrears. For we stood possessed, in rudiment, of meansof observation, means for travelling and acquisition, qualifying menfor a larger knowledge than had yet been attempted. These were now tobe directed with new accuracy and ardour upon the fabric and behaviourof the world of sense. Our debt to the great masters in physicalscience who overtook and almost outstripped the task cannot bemeasured; and, under the honourable leadership of Ruskin, we may allwell do penance if we have failed "in the respect due to their greatpowers of thought, or in the admiration due to the far scope of theirdiscovery. "[223] With what miraculous mental energy and divine goodfortune--as Romans said of their soldiers--did our men of curiosityface the apparently impenetrable mysteries of nature! And how naturalit was that immense accessions of knowledge, unrelated to thespiritual facts of life, should discredit Christian faith, by theapparent superiority of the new work to the feeble and unprogressiveknowledge of Christian believers! The day is coming when men of thismental character and rank, of this curiosity, this energy and thisgood fortune in investigation, will be employed in opening mysteriesof a spiritual nature. They will silence with masterful witness theover-confident denials of naturalism. They will be in danger of thewidespread recognition which thirty years ago accompanied everyutterance of Huxley, Tyndall, Spencer. They will contribute, in spiteof adulation, to the advance of sober religious and moral science. 

And this result will be due to Darwin, first because by raising thedignity of natural science, he encouraged the development of thescientific mind; secondly because he gave to religious students theexample of patient and ardent investigation; and thirdly because bythe pressure of naturalistic criticism the religious have been drivento ascertain the causes of their own convictions, a work in which theywere not without the sympathy of men of science. [224]

In leaving the subject of scientific religious inquiry, I will onlyadd that I do not believe it receives any important help--andcertainly it suffers incidentally much damaging interruption--from thestudy of abnormal manifestations or abnormal conditions ofpersonality. 

(3) Both of the above effects seem to me of high, perhaps the veryhighest, importance to faith and to thought. But, under the thirdhead, I name two which are more directly traceable to the personalwork of Darwin, and more definitely characteristic of the age in whichhis influence was paramount: viz. The influence of the two conceptionsof evolution and natural selection upon the doctrine of creation andof design respectively. 

It is impossible here, though it is necessary for a complete sketch ofthe matter, to distinguish the different elements and channels of thisDarwinian influence; in Darwin's own writings, in the vigourouspolemic of Huxley, and strangely enough, but very actually for popularthought, in the teaching of the definitely anti-Darwinian evolutionistSpencer. 

Under the head of the directly and purely Darwinian elements I shouldclass as preeminent the work of Wallace and of Bates; for no two setsof facts have done more to fix in ordinary intelligent minds a beliefin organic evolution and in natural selection as its guiding factorthan the facts of geographical distribution and of protective colourand mimicry. The facts of geology were difficult to grasp and thepublic and theologians heard more often of the imperfection than ofthe extent of the geological record. The witness of embryology, depending to a great extent upon microscopic work, was and is beyondthe appreciation of persons occupied in fields of work other thanbiology. 

III

From the influence in religion of scientific modes of thought we passto the influence of particular biological conceptions. The formereffect comes by way of analogy, example, encouragement and challenge;inspiring or provoking kindred or similar modes of thought in thefield of theology; the latter by a collision of opinions upon mattersof fact or conjecture which seem to concern both science and religion. 

In the case of Darwinism the story of this collision is familiar, andfalls under the heads of evolution and natural selection, the doctrineof descent with modification, and the doctrine of its guidance ordetermination by the struggle for existence between related varieties. These doctrines, though associated and interdependent, and in popularthought not only combined but confused, must be considered separately. It is true that the ancient doctrine of Evolution, in spite of theingenuity and ardour of Lamarck, remained a dream tantalising theintellectual ambition of naturalists, until the day when Darwin madeit conceivable by suggesting the machinery of its guidance. And, further, the idea of natural selection has so effectively opened thedoor of research and stimulated observation in a score of principaldirections that, even if the Darwinian explanation became one day muchless convincing than, in spite of recent criticism, it now is, yet itspassing, supposing it to pass, would leave the doctrine of Evolutionimmeasurably and permanently strengthened. For in the interests of thetheory of selection, "Für Darwin, " as Müller wrote, facts have beencollected which remain in any case evidence of the reality of descentwith modification. 

But still, though thus united in the modern history of convictions, though united and confused in the collision of biological andtraditional opinion, yet evolution and natural selection must beseparated in theological no less than in biological estimation. Evolution seemed inconsistent with Creation; natural selection withProvidence and Divine design. 

Discussion was maintained about these points for many years and withmuch dark heat. It ranged over many particular topics and engagedminds different in tone, in quality, and in accomplishment. There wasat most times a degree of misconception. Some naturalists attributedto theologians in general a poverty of thought which belonged reallyto men of a particular temper or training. The "timid theism"discerned in Darwin by so cautious a theologian as Liddon[225] wassupposed by many biologists to be the necessary foundation of anhonest Christianity. It was really more characteristic of devout_naturalists_ like Philip Henry Gosse, than of religious believers assuch. [226] The study of theologians more considerable and even moretypically conservative than Liddon does not confirm the description ofreligious intolerance given in good faith, but in serious ignorance, by a disputant so acute, so observant and so candid as Huxley. Something hid from each other's knowledge the devoted pilgrims in twogreat ways of thought. The truth may be, that naturalists took theirview of what creation was from Christian men of science who naturallylooked in their own special studies for the supports and illustrationsof their religious belief. Of almost every labourious student it maybe said: "_Hic ab arte sua non recessit_. " And both the believing andthe denying naturalists, confining habitual attention to a part ofexperience, are apt to affirm and deny with trenchant vigour andsomething of a narrow clearness "_Qui respiciunt ad pauca, de facilipronunciant_. "[227]

Newman says of some secular teachers that "they persuade the world ofwhat is false by urging upon it what is true. " Of some early opponentsof Darwin it might be said by a candid friend that, in all sincerityof devotion to truth, they tried to persuade the world of what is trueby urging upon it what is false. If naturalists took their version oforthodoxy from amateurs in theology, some conservative Christians, instead of learning what evolution meant to its regular exponents, took their view of it from celebrated persons, not of the front rankin theology or in thought, but eager to take account of publicmovements and able to arrest public attention. 

Cleverness and eloquence on both sides certainly had their share inproducing the very great and general disturbance of men's minds in theearly days of Darwinian teaching. But by far the greater part of thatdisturbance was due to the practical novelty and the profoundimportance of the teaching itself, and to the fact that thecontroversy about evolution quickly became much more public than anycontroversy of equal seriousness had been for many generations. 

We must not think lightly of that great disturbance because it has, insome real sense, done its work, and because it is impossible in daysof more coolness and light, to recover a full sense of its very realdifficulties. 

Those who would know them better should add to the calm records ofDarwin[228] and to the story of Huxley's impassioned championship, allthat they can learn of George Romanes. [229] For his life was absorbedin this very struggle and reproduced its stages. It began in a certainassured simplicity of biblical interpretation; it went on, through theglories and adventures of a paladin in Darwin's train, to the darknessand dismay of a man who saw all his most cherished beliefs rendered, as he thought, incredible. [230] He lived to find the freer faith forwhich process and purpose are not irreconcilable, but necessary to oneanother. His development, scientific, intellectual and moral, wasitself of high significance; and its record is of unique value to ourown generation, so near the age of that doubt and yet so far from it;certainly still much in need of the caution and courage by which pastendurance prepares men for new emergencies. We have little enoughreason to be sure that in the discussions awaiting us we shall do aswell as our predecessors in theirs. Remembering their endurance ofmental pain, their ardour in mental labour, the heroic temper and thehigh sincerity of controversialists on either side, we may well speakof our fathers in such words of modesty and self-judgment as Draytonused when he sang the victors of Agincourt. The progress of biblicalstudy, in the departments of Introduction and Exegesis, resulting inthe recovery of a point of view anciently tolerated if not prevalent, has altered some of the conditions of that discussion. In the yearsnear 1858, the witness of Scripture was adduced both by Christianadvocates and their critics as if unmistakably irreconcilable withEvolution. 

Huxley[231] found the path of the blameless naturalist everywhereblocked by "Moses": the believer in revelation was generally held tobe forced to a choice between revealed cosmogony and the scientificaccount of origins. It is not clear how far the change in Biblicalinterpretation is due to natural science, and how far to the vitalmovements of theological study which have been quite independent ofthe controversy about species. It belongs to a general renewal ofChristian movement, the recovery of a heritage. "SpecialCreation"--really a biological rather than a theologicalconception, --seems in its rigid form to have been a recent elementeven in English biblical orthodoxy. 

The Middle Ages had no suspicion that religious faith forbad inquiryinto the natural origination of the different forms of life. Bartholomaeus Anglicus, an English Franciscan of the thirteenthcentury, was a mutationist in his way, as Aristotle, "the Philosopher"of the Christian Schoolmen, had been in his. So late as theseventeenth century, as we learn not only from early proceedings ofthe Royal Society, but from a writer so homely and so regularly piousas Walton, the variation of species and "spontaneous" generations hadno theological bearing, except as instances of that various wonder ofthe world which in devout minds is food for devotion. 

It was in the eighteenth century that the harder statement took shape. Something in the preciseness of that age, its exaltation of law, itscold passion for a stable and measured universe, its cold denial, itscold affirmation of the power of God, a God of ice, is the occasion ofthat rigidity of religious thought about the living world which Darwinby accident challenged, or rather by one of those movements of geniuswhich, Goethe[232] declares, are "elevated above all earthly control. "

If religious thought in the eighteenth century was aimed at a fixedand nearly finite world of spirit, it followed in all these respectsthe secular and critical lead. "La philosophie réformatrice duXVIII^{e} siècle[233] ramenait la nature et la société à desmécanismes que la pensée réfléchie peut concevoir et récomposer. " Infact, religion in a mechanical age is condemned if it takes any but amechanical tone. Butler's thought was too moving, too vital, tooevolutionary, for the sceptics of his time. In a rationalist, encyclopaedic period, religion also must give hard outline to itsfacts, it must be able to display its secret to any sensible man inthe language used by all sensible men. Milton's prophetic geniusfurnished the eighteenth century, out of the depth of the passionateage before it, with the theological tone it was to need. In spite ofthe austere magnificence of his devotion, he gives to smaller souls adangerous lead. The rigidity of Scripture exegesis belonged to thisstately but imperfectly sensitive mode of thought. It passed away withthe influence of the older rationalists whose precise denials matchedthe precise and limited affirmations of the static orthodoxy. 

I shall, then, leave the specially biblical aspect of thedebate--interesting as it is and even useful, as in Huxley'scorrespondence with the Duke of Argyll and others in 1892[234]--inorder to consider without complication the permanent elements ofChristian thought brought into question by the teaching of evolution. 

Such permanent elements are the doctrine of God as Creator of theuniverse, and the doctrine of man as spiritual and unique. Upon boththe doctrine of evolution seemed to fall with crushing force. 

With regard to Man I leave out, acknowledging a grave omission, thedoctrine of the Fall and of Sin. And I do so because these have notyet, as I believe, been adequately treated: here the fruitful reactionto the stimulus of evolution is yet to come. The doctrine of sin, indeed, falls principally within the scope of that discussion whichhas followed or displaced the Darwinian; and without it the Fallcannot be usefully considered. For the question about the Fall is aquestion not merely of origins, but of the interpretation of moralfacts whose moral reality must first be established. 

I confine myself therefore to Creation and the dignity of man. 

The meaning of evolution, in the most general terms, is that thedifferentiation of forms is not essentially separate from theirbehaviour and use; that if these are within the scope of study, thatis also; that the world has taken the form we see by movements notunlike those we now see in progress; that what may be called proximateorigins are continuous in the way of force and matter, continuous inthe way of life, with actual occurrences and actual characteristics. All this has no revolutionary bearing upon the question of ultimateorigins. The whole is a statement about process. It says nothing tometaphysicians about cause. It simply brings within the scope ofobservation or conjecture that series of changes which has given theirspecial characters to the different parts of the world we see. Inparticular, evolutionary science aspires to the discovery of theprocess or order of the appearance of life itself: if it were toachieve its aim it could say nothing of the cause of this or indeed ofthe most familiar occurrences. We should have become spectators orconvinced historians of an event which, in respect of its cause andultimate meaning, would be still impenetrable. 

With regard to the origin of species, supposing life alreadyestablished, biological science has the well founded hopes and themeasure of success with which we are all familiar. All this has, itwould seem, little chance of collision with a consistent theism, adoctrine which has its own difficulties unconnected with anyparticular view of order or process. But when it was stated thatspecies had arisen by processes through which new species were stillbeing made, evolutionism came into collision with a statement, traditionally religious, that species were formed and fixed once forall and long ago. 

What is the theological import of such a statement when it is regardedas essential to belief in God? Simply that God's activity, withrespect to the formation of living creatures, ceased at some point inpast time. 

"God rested" is made the touchstone of orthodoxy. And when, under thepressure of the evidences, we found ourselves obliged to acknowledgeand assert the present and persistent power of God, in the maintenanceand in the continued formation of "types, " what happened was theabolition of a time-limit. We were forced only to a bolder claim, toa theistic language less halting, more consistent, more thorough inits own line, as well as better qualified to assimilate and modifysuch schemes as Von Hartmann's philosophy of the Unconscious--aphilosophy, by the way, quite intolerant of a merely mechanicalevolution. [235]

Here was not the retrenchment of an extravagant assertion, but theexpansion of one which was faltering and inadequate. The traditionalstatement did not need paring down so as to pass the meshes of a newand exacting criticism. It was itself a net meant to surround andenclose experience; and we must increase its size and close its meshto hold newly disclosed facts of life. The world, which had seemed afixed picture or model, gained first perspective and then solidity andmovement. We had a glimpse of organic _history_; and Christian thoughtbecame more living and more assured as it met the larger view of life. 

However unsatisfactory the new attitude might be to our critics, toChristians the reform was positive. What was discarded was alimitation, a negation. The movement was essentially conservative, even actually reconstructive. For the language disused was a languageinconsistent with the definitions of orthodoxy; it set bounds to theinfinite, and by implication withdrew from the creative rule all suchprocesses as could be brought within the descriptions of research. Itascribed fixity and finality to that "creature" in which an apostletaught us to recognise the birth-struggles of an unexhausted progress. It tended to banish mystery from the world we see, and to confine itto a remote first age. 

In the reformed, the restored, language of religion, Creation becameagain not a link in a rational series to complete a circle of thesciences, but the mysterious and permanent relation between theinfinite and the finite, between the moving changes we know in part, and the Power, after the fashion of that observation, unknown, whichis itself "unmoved all motion's source. "[236]

With regard to man it is hardly necessary, even were it possible, toillustrate the application of this bolder faith. When the record ofhis high extraction fell under dispute, we were driven to acontemplation of the whole of his life, rather than of a part and thatpart out of sight. We remembered again, out of Aristotle, that theresult of a process interprets its beginnings. We were obliged to readthe title of such dignity as we may claim, in results and still morein aspirations. 

Some men still measure the value of great present facts inlife--reason and virtue and sacrifice--by what a self-disparagedreason can collect of the meaner rudiments of these noble gifts. Mr. Balfour has admirably displayed the discrepancy, in this view, betweenthe alleged origin and the alleged authority of reason. Such anargument ought to be used not to discredit the confident reason, butto illuminate and dignify its dark beginnings, and to show that atevery step in the long course of growth a Power was at work which isnot included in any term or in all the terms of the series. 

I submit that the more men know of actual Christian teaching, itsfidelity to the past, and its sincerity in face of discovery, the morecertainly they will judge that the stimulus of the doctrine ofevolution has produced in the long run vigour as well as flexibilityin the doctrine of Creation and of man. 

I pass from Evolution in general to Natural Selection. 

The character in religious language which I have for short calledmechanical was not absent in the argument from design as stated beforeDarwin. It seemed to have reference to a world conceived as fixed. Itpointed, not to the plastic capacity and energy of living matter, butto the fixed adaptation of this and that organ to an unchanging placeor function. 

Mr. Hobhouse has given us the valuable phrase "a niche of organicopportunity. " Such a phrase would have borne a different sense innon-evolutionary thought. In that thought, the opportunity was anopportunity for the Creative Power, and Design appeared in thepreparation of the organism to fit the niche. The idea of the nicheand its occupant growing together from simpler to more complex mutualadjustment was unwelcome to this teleology. If the adaptation wastraced to the influence, through competition, of the environment, theold teleology lost an illustration and a proof. For the cogency of theproof in every instance depended upon the absence of explanation. Where the process of adaptation was discerned, the evidence of Purposeor Design was weak. It was strong only when the natural antecedentswere not discovered, strongest when they could be declaredundiscoverable. 

Paley's favourite word is "Contrivance"; and for him contrivance ismost certain where production is most obscure. He points out thephysiological advantage of the _valvulae conniventes_ to man, and theadvantage for teleology of the fact that they cannot have been formedby "action and pressure. " What is not due to pressure may beattributed to design, and when a "mechanical" process more subtle thanpressure was suggested, the case for design was so far weakened. Thecumulative proof from the multitude of instances began to disappearwhen, in selection, a natural sequence was suggested in which all theadaptations might be reached by the motive power of life, andespecially when, as in Darwin's teaching, there was full recognitionof the reactions of life to the stimulus of circumstance. "Theorganism fits the niche, " said the teleologist, "because the Creatorformed it so as to fit. " "The organism fits the niche, " said thenaturalist, "because unless it fitted it could not exist. " "It wasfitted to survive, " said the theologian. "It survives because itfits, " said the selectionist. The two forms of statement are notincompatible; but the new statement, by provision of an ideallyuniversal explanation of process, was hostile to a doctrine of purposewhich relied upon evidences always exceptional however numerous. Science persistently presses on to find the universal machinery ofadaptation in this planet; and whether this be found in selection, orin direct-effect, or in vital reactions resulting in large changes, orin a combination of these and other factors, it must always be opposedto the conception of a Divine Power here and there but not everywhereactive. 

For science, the Divine must be constant, operative everywhere and inevery quality and power, in environment and in organism, in stimulusand in reaction, in variation and in struggle, in hereditaryequilibrium, and in "the unstable state of species"; equally presenton both sides of every strain, in all pressures and in allresistances, in short in the general wonder of life and the world. Andthis is exactly what the Divine Power must be for religious faith. 

The point I wish once more to make is that the necessary readjustmentof teleology, so as to make it depend upon the contemplation of thewhole instead of a part, is advantageous quite as much to theology asto science. For the older view failed in courage. Here again ourtheism was not sufficiently theistic. 

Where results seemed inevitable, it dared not claim them as God-given. In the argument from Design it spoke not of God in the sense oftheology, but of a Contriver, immensely, not infinitely wise and good, working within a world, the scene, rather than the ever dependentoutcome, of His Wisdom; working in such emergencies and opportunitiesas occurred, by forces not altogether within His control, towards anend beyond Himself. It gave us, instead of the awful reverence due tothe Cause of all substance and form, all love and wisdom, adangerously detached appreciation of an ingenuity and benevolencemeritorious in aim and often surprisingly successful in contrivance. 

The old teleology was more useful to science than to religion, andthe design-naturalists ought to be gratefully remembered byBiologists. Their search for evidences led them to an eager study ofadaptations and of minute forms, a study such as we have now anincentive to in the theory of Natural Selection. One hardly meets withthe same ardour in microscopical research until we come to modernworkers. But the argument from Design was never of great importance tofaith. Still, to rid it of this character was worth all the stress andanxiety of the gallant old war. If Darwin had done nothing else forus, we are to-day deeply in his debt for this. The world is not lessvenerable to us now, not less eloquent of the causing mind, rathermuch more eloquent and sacred. But our wonder is not that "theunderjaw of the swine works under the ground" or in any or all ofthose particular adaptations which Paley collected with so much skill, but that a purpose transcending, though resembling, our own purposes, is everywhere manifest; that what we live in is a whole, mutuallysustaining, eventful and beautiful, where the "dead" forces feed theenergies of life, and life sustains a stranger existence, able in somereal measure to contemplate the whole, of which, mechanicallyconsidered, it is a minor product and a rare ingredient. Here, again, the change was altogether positive. It was not the escape of a vesselin a storm with loss of spars and rigging, not a shortening of sail tosave the masts and make a port of refuge. It was rather the emergencefrom narrow channels to an open sea. We had propelled the great ship, finding purchase here and there for slow and uncertain movement. Now, in deep water, we spread large canvas to a favouring breeze. 

The scattered traces of design might be forgotten or obliterated. Butthe broad impression of Order became plainer when seen at due distanceand in sufficient range of effect, and the evidence of love and wisdomin the universe could be trusted more securely for the loss of theparticular calculation of their machinery. 

Many other topics of faith are affected by modern biology. In some ofthese we have learnt at present only a wise caution, a wiseuncertainty. We stand before the newly unfolded spectacle ofsuffering, silenced; with faith not scientifically reassured but stillholding fast certain other clues of conviction. In many importanttopics we are at a loss. But in others, and among them those I havementioned, we have passed beyond this negative state and find faithpositively strengthened and more fully expressed. 

We have gained also a language and a habit of thought more fit for thegreat and dark problems that remain, less liable to damagingconflicts, equipped for more rapid assimilation of knowledge. And bythis change biology itself is a gainer. For, relieved of fruitlessencounters with popular religion, it may advance with surer aim alongthe path of really scientific life-study which was reopened for modernmen by the publication of _The Origin of Species_. 

Charles Darwin regretted that, in following science, he had not done"more direct good"[237] to his fellow-creatures. He has, in fact, rendered substantial service to interests bound up with the dailyconduct and hopes of common men; for his work has led to improvementsin the preaching of the Christian faith. 

FOOTNOTES:

[Footnote 218: F. R. Tennant: "The Being of God in the light ofPhysical Science, " in _Essays on some theological questions of theday_. London, 1905. ]

[Footnote 219: _Evolutionisme et Platonisme_, pp. 45, 46, 47. Paris, 1908. ]

[Footnote 220: _Essays of Elia_, "New Year's Eve, " p. 41; Ainger'sedition. London, 1899. ]

[Footnote 221: Such an example is given in Baron F. Von Hügel'srecently finished book, the result of thirty years' research: _TheMystical Element of Religion, as studied in Saint Catherine of Genoaand her Friends_. London, 1908. ]

[Footnote 222: G. Tyrrell, in _Mediaevalism_, has a chapter which isfull of the important _moral_ element in a scientific attitude. "Theonly infallible guardian of truth is the spirit of truthfulness. "_Mediaevalism_, p. 182, London, 1908. ]

[Footnote 223: _Queen of the Air_, Preface, p. Vii. London, 1906. ]

[Footnote 224: The scientific rank of its writer justifies theinsertion of the following letter from the late Sir JohnBurdon-Sanderson to me. In the lecture referred to I had described themethods of Professor Moseley in teaching Biology as affording asuggestion of the scientific treatment of religion. 

OXFORD, _April 30, 1902_. 

DEAR SIR:

 I feel that I must express to you my thanks for the discourse which I had the pleasure of listening to yesterday afternoon. 

 I do not mean to say that I was able to follow all that you said as to the identity of Method in the two fields of Science and Religion, but I recognise that the "mysticism" of which you spoke gives us the only way by which the two fields can be brought into relation. 

 Among much that was memorable, nothing interested me more than what you said of Moseley. 

 No one, I am sure, knew better than you the value of his teaching and in what that value consisted. 

Yours faithfully, J. BURDON-SANDERSON. 

]

[Footnote 225: H. P. Liddon, _The Recovery of S. Thomas_; a sermonpreached in St. Paul's, London, on April 23rd, 1882 (the Sunday afterDarwin's death). ]

[Footnote 226: Dr. Pusey (_Unscience not Science adverse to Faith_, 1878) writes: "The questions as to 'species, ' of what variations theanimal world is capable, whether the species be more or fewer, whetheraccidental variations may become hereditary . .. And the like, naturally fall under the province of science. In all these questionsMr. Darwin's careful observations gained for him a deservedapprobation and confidence. "]

[Footnote 227: Aristotle, in Bacon, quoted by Newman in his _Idea of aUniversity_, p. 78. London, 1873. ]

[Footnote 228: _Life and Letters_ and _More Letters of CharlesDarwin. _]

[Footnote 229: _Life and Letters_, London, 1896. _Thoughts onReligion_, London, 1895. _Candid Examination of Theism_, London, 1878. ]

[Footnote 230: "Never in the history of man has so terrific a calamitybefallen the race as that which all who look may now (viz. Inconsequence of the scientific victory of Darwin) behold advancing as adeluge black with destruction, resistless in might, uprooting our mostcherished hopes, engulphing our most precious creed, and burying ourhighest life in mindless destruction. "--_A Candid Examination ofTheism_, p. 51. ]

[Footnote 231: _Science and Christian Tradition. _ London, 1904. ]

[Footnote 232: "No productiveness of the highest kind . .. Is in thepower of anyone. "--_Conversations of Goethe with Eckermann and Soret_. London, 1850. ]

[Footnote 233: Berthelot, _Evolutionisme et Platonisme_, Paris, 1908, p. 45. ]

[Footnote 234: _Times_, 1892, _passim. _]

[Footnote 235: See Von Hartmann's _Wahrheit und Irrthum inDarwinismus_. Berlin, 1875. ]

[Footnote 236: Hymn of the Church--

 Rerum Deus tenax vigor, Immotus in te permanens. 

]

[Footnote 237: _Life and Letters_, Vol. III. P. 359. ]

IX

DARWINISM AND HISTORY

BY J. B. BURY, LITT. D. , LL. D. 

_Regius Professor of Modern History in the University of Cambridge_

1. Evolution, and the principles associated with the Darwinian theory, could not fail to exert a considerable influence on the studiesconnected with the history of civilised man. The speculations whichare known as "philosophy of history, " as well as the sciences ofanthropology, ethnography, and sociology (sciences which though theystand on their own feet are for the historian auxiliary), have beendeeply affected by these principles. Historiographers, indeed, havewith few exceptions made little attempt to apply them; but the growthof historical study in the nineteenth century has been determined andcharacterised by the same general principle which has underlain thesimultaneous developments of the study of nature, namely the _geneticidea_. The "historical" conception of nature, which has produced thehistory of the solar system, the story of the earth, the genealogiesof telluric organisms, and has revolutionised natural science, belongsto the same order of thought as the conception of human history as acontinuous, genetic, causal process--a conception which hasrevolutionised historical research and made it scientific. Beforeproceeding to consider the application of evolutional principles, itwill be pertinent to notice the rise of this new view. 

2. With the Greeks and Romans history had been either a descriptiverecord or had been written in practical interests. The most eminentof the ancient historians were pragmatical; that is, they regardedhistory as an instructress in statesmanship, or in the art of war, orin morals. Their records reached back such a short way, theirexperience was so brief, that they never attained to the conception ofcontinuous process, or realised the significance of time; and theynever viewed the history of human societies as a phenomenon to beinvestigated for its own sake. In the middle ages there was still lesschance of the emergence of the ideas of progress and development. Suchnotions were excluded by the fundamental doctrines of the dominantreligion which bounded and bound men's minds. As the course of historywas held to be determined from hour to hour by the arbitrary will ofan extra cosmic person, there could be no self-contained causaldevelopment, only a dispensation imposed from without. And as it wasbelieved that the world was within no great distance from the end ofthis dispensation, there was no motive to take much interest inunderstanding the temporal, which was to be only temporary. 

The intellectual movements of the fifteenth and sixteenth centuriesprepared the way for a new conception, but it did not emergeimmediately. The historians of the Renaissance period simply revertedto the ancient pragmatical view. For Machiavelli, exactly as forThucydides and Polybius, the use of studying history was instructionin the art of politics. The Renaissance itself was the appearance of anew culture, different from anything that had gone before; but at thetime men were not conscious of this; they saw clearly that thetraditions of classical antiquity had been lost for a long period, andthey were seeking to revive them, but otherwise they did not perceivethat the world had moved, and that their own spirit, culture, andconditions were entirely unlike those of the thirteenth century. Itwas hardly till the seventeenth century that the presence of a newage, as different from the middle ages as from the ages of Greece andRome, was fully realised. It was then that the triple division ofancient, medieval, and modern was first applied to the history ofwestern civilisation. Whatever objections may be urged against thisdivision, which has now become almost a category of thought, it marksa most significant advance in man's view of his own past. He hasbecome conscious of the immense changes in civilisation which havecome about slowly in the course of time, and history confronts himwith a new aspect. He has to explain how those changes have beenproduced, how the transformations were effected. The appearance ofthis problem was almost simultaneous with the rise of rationalism, andthe great historians and thinkers of the eighteenth century, such asMontesquieu, Voltaire, Gibbon, attempted to explain the movement ofcivilisation by purely natural causes. These brilliant writersprepared the way for the genetic history of the following century. Butin the spirit of the _Aufklärung_, that eighteenth-centuryEnlightenment to which they belonged, they were concerned to judge allphenomena before the tribunal of reason; and the apotheosis of"reason" tended to foster a certain superior _a priori_ attitude, which was not favourable to objective treatment and was incompatiblewith a "historical sense. " Moreover the traditions of pragmaticalhistoriography had by no means disappeared. 

3. In the first quarter of the nineteenth century the meaning ofgenetic history was fully realised. "Genetic" perhaps is as good aword as can be found for the conception which in this century wasapplied to so many branches of knowledge in the spheres both of natureand of mind. It does not commit us to the doctrine proper ofevolution, nor yet to any teleological hypothesis such as is impliedin "progress. " For history it meant that the present condition of thehuman race is simply and strictly the result of a causal series (orset of causal series)--a continuous succession of changes, where eachstate arises causally out of the preceding; and that the business ofhistorians is to trace this genetic process, to explain each change, and ultimately to grasp' the complete development of the life ofhumanity. Three influential writers, who appeared at this stage andhelped to initiate a new period of research, may specially bementioned. Ranke in 1824 definitely repudiated the pragmatical viewwhich ascribes to history the duties of an instructress, and with noless decision renounced the function, assumed by the historians of the_Aufklärung_, to judge the past; it was his business, he said, merelyto show how things really happened. Niebuhr was already working in thesame spirit and did more than any other writer to establish theprinciple that historical transactions must be related to the ideasand conditions of their age. Savigny about the same time founded the"historical school" of law. He sought to show that law was not thecreation of an enlightened will, but grew out of custom and wasdeveloped by a series of adaptations and rejections, thus applying theconception of evolution. He helped to diffuse the notion that all theinstitutions of a society or a nation are as closely interconnected asthe parts of a living organism. 

4. The conception of the history of man as a causal development meantthe elevation of historical inquiry to the dignity of a science. Justas the study of bees cannot become scientific so long as the student'sinterest in them is only to procure honey or to derive moral lessonsfrom the labours of "the little busy bee, " so the history of humansocieties cannot become the object of pure scientific investigation solong as man estimates its value in pragmatical scales. Nor can itbecome a science until it is conceived as lying entirely within asphere in which the law of cause and effect has unreserved andunrestricted dominion. On the other hand, once history is envisaged asa causal process, which contains within itself the explanation of thedevelopment of man from his primitive state to the point which he hasreached, such a process necessarily becomes the object of scientificinvestigation and the interest in it is scientific curiosity. 

At the same time, the instruments were sharpened and refined. HereWolf, a philologist with historical instinct, was a pioneer. His_Prolegomena_ to Homer (1795) announced new modes of attack. Historical investigation was soon transformed by the elaboration ofnew methods. 

5. "Progress" involves a judgment of value, which is not involved inthe conception of history as a genetic process. It is also an ideadistinct from that of evolution. Nevertheless it is closely related tothe ideas which revolutionised history at the beginning of the lastcentury; it swam into men's ken simultaneously; and it helpedeffectively to establish the notion of history as a continuous processand to emphasise the significance of time. Passing over earlieranticipations, I may point to a _Discours_ of Turgot (1750), wherehistory is presented as a process in which "the total mass of thehuman race" "marches continually though sometimes slowly to an everincreasing perfection. " That is a clear statement of the conceptionwhich Turgot's friend Condorcet elaborated in the famous work, published in 1795, _Esquisse d'un tableau historique des progrès del'esprit humain_. This work first treated with explicit fulness theidea to which a leading role was to fall in the ideology of thenineteenth century. Condorcet's book reflects the triumphs of the_Tiers état_, whose growing importance had also inspired Turgot; itwas the political changes in the eighteenth century which led to thedoctrine, emphatically formulated by Condorcet, that the masses arethe most important element in the historical process. I dwell on thisbecause, though Condorcet had no idea of evolution, the predominantimportance of the masses was the assumption which made it possible toapply evolutional principles to history. And it enabled Condorcethimself to maintain that the history of civilisation, a progress stillfar from being complete, was a development conditioned by generallaws. 

6. The assimilation of society to an organism, which was a governingnotion in the school of Savigny, and the conception of progress, combined to produce the idea of an organic development, in which thehistorian has to determine the central principle or leading character. This is illustrated by the apotheosis of democracy in Tocqueville's_Démocratie en Amérique_, where the theory is maintained that "thegradual and progressive development of equality is at once the pastand the future of the history of men. " The same two principles arecombined in the doctrine of Spencer (who held that society is anorganism, though he also contemplated its being what he calls a"super-organic aggregate"), [238] that social evolution is aprogressive change from militarism to industrialism. 

7. The idea of development assumed another form in the speculations ofGerman idealism. Hegel conceived the successive periods of history ascorresponding to the ascending phases or ideas in the self-evolutionof his Absolute Being. His _Lectures on the Philosophy of History_were published in 1837 after his death. His philosophy had aconsiderable effect, direct and indirect, on the treatment of historyby historians, and although he was superficial and unscientifichimself in dealing with historical phenomena, he contributed muchtowards making the idea of historical development familiar. Ranke wasinfluenced, if not by Hegel himself, at least by the Idealisticphilosophies of which Hegel's was the greatest. He was inclined toconceive the stages in the process of history as marked byincarnations, as it were, of ideas, and sometimes speaks as if theideas were independent forces, with hands and feet. But while Hegeldetermined his ideas by _a priori_ logic, Ranke obtained his byinduction--by a strict investigation of the phenomena; so that he wasscientific in his method and work, and was influenced by Hegelianprepossessions only in the kind of significance which he was disposedto ascribe to his results. It is to be noted that the theory of Hegelimplied a judgment of value; the movement was a progress towardsperfection. 

8. In France, Comte approached the subject from a different side, andexercised, outside Germany, a far wider influence than Hegel. The 4thvolume of his _Cours de philosophie positive_, which appeared in 1839, created sociology and treated history as a part of this new science, namely as "social dynamics. " Comte sought the key for unfoldinghistorical development, in what he called the social-psychologicalpoint of view, and he worked out the two ideas which had beenenunciated by Condorcet: that the historian's attention should bedirected not, as hitherto, principally to eminent individuals, but tothe collective behaviour of the masses, as being the most importantelement in the process; and that, as in nature, so in history, thereare general laws, necessary and constant, which condition thedevelopment. The two points are intimately connected, for it is onlywhen the masses are moved into the foreground that regularity, uniformity, and law can be conceived as applicable. To determine thesocial-psychological laws which have controlled the development is, according to Comte, the task of sociologists and historians. 

9. The hypothesis of general laws operative in history was carriedfurther in a book which appeared in England twenty years later andexercised an influence in Europe far beyond its intrinsic merit, Buckle's _History of Civilisation in England_ (1857-61). Buckle owedmuch to Comte, and followed him, or rather outdid him, in regardingintellect as the most important factor conditioning the upwarddevelopment of man, so that progress, according to him, consisted inthe victory of the intellectual over the moral laws. 

10. The tendency of Comte and Buckle to assimilate history to thesciences of nature by reducing it to general "laws, " derived stimulusand plausibility from the vista offered by the study of statistics, in which the Belgian Quetelet, whose book _Sur l'homme_ appeared in1835, discerned endless possibilities. The astonishing uniformitieswhich statistical inquiry disclosed led to the belief that it was onlya question of collecting a sufficient amount of statistical material, to enable us to predict how a given social group will act in aparticular case. Bourdeau, a disciple of this school, looks forward tothe time when historical science will become entirely quantitative. The actions of prominent individuals, which are generally consideredto have altered or determined the course of things, are obviously notamenable to statistical computation or explicable by general laws. Thinkers like Buckle sought to minimise their importance or explainthem away. 

11. These indications may suffice to show that the new efforts tointerpret history which marked the first half of the nineteenthcentury were governed by conceptions closely related to those whichwere current in the field of natural science and which resulted in thedoctrine of evolution. The genetic principle, progressive development, general laws, the significance of time, the conception of society asan organic aggregate, the metaphysical theory of history as theself-evolution of spirit, --all these ideas show that historicalinquiry had been advancing independently on somewhat parallel lines tothe sciences of nature. It was necessary to bring this out in order toappreciate the influence of Darwinism. 

12. In the course of the dozen years which elapsed between theappearances of _The Origin of Species_ (observe that the first volumeof Buckle's work was published just two years before) and of _TheDescent of Man_ (1871), the hypothesis of Lamarck that man is theco-descendant with other species of some lower extinct form wasadmitted to have been raised to the rank of an established fact bymost thinkers whose brains were not working under the constraint oftheological authority. 

One important effect of the discovery of this fact (I am not speakingnow of the Darwinian explanation) was to assign to history a definiteplace in the coordinated whole of knowledge, and relate it moreclosely to other sciences. It had indeed a defined logical place insystems such as Hegel's and Comte's; but Darwinism certified itsstanding convincingly and without more ado. The prevailing doctrinethat man was created _ex abrupto_ had placed history in an isolatedposition, disconnected with the sciences of nature. Anthropology, which deals with the animal _anthropos_, now comes into line withzoology, and brings it into relation with history. [239] Man'scondition at the present day is the result of a series oftransformations, going back to the most primitive phase of society, which is the ideal (unattainable) beginning of history. But thatbeginning had emerged without any breach of continuity from adevelopment which carries us back to a quadrimane ancestor, stillfurther back (according to Darwin's conjecture) to a marine animal ofthe ascidian type, and then through remoter periods to the lowest formof organism. It is essential in this theory that though links havebeen lost there was no break in the gradual development; and thisconception of a continuous progress in the evolution of life, resulting in the appearance of uncivilised Anthropos, helped toreinforce, and increase a belief in, the conception of the history ofcivilised Anthropos as itself also a continuous progressivedevelopment. 

13. Thus the diffusion of the Darwinian theory of the origin of man, by emphasising the idea of continuity and breaking down the barriersbetween the human and animal kingdoms, has had an important effect inestablishing the position of history among the sciences which dealwith telluric development. The perspective of history is merged in alarger perspective of development. As one of the objects of biology isto find the exact steps in the genealogy of man from the lowestorganic form, so the scope of history is to determine the stages inthe unique causal series from the most rudimentary to the presentstate of human civilisation. 

It is to be observed that the interest in historical research impliedby this conception need not be that of Comte. In the PositivePhilosophy history is part of sociology; the interest in it is todiscover the sociological laws. In the view of which I have justspoken, history is permitted to be an end in itself; thereconstruction of the genetic process is an independent interest. Forthe purpose of the reconstruction, sociology, as well as physicalgeography, biology, psychology, is necessary; the sociologist and thehistorian play into each other's hands; but the object of the formeris to establish generalisations; the aim of the latter is to trace indetail a singular causal sequence. 

14. The success of the evolutional theory helped to discredit theassumption or at least the invocation of transcendent causes. Philosophically of course it is compatible with theism, but historianshave for the most part desisted from invoking the naive conception ofa "god in history" to explain historical movements. A historian may bea theist; but, so far as his work is concerned, this particular beliefis otiose. Otherwise indeed (as was remarked above) history could notbe a science; for with a _deus ex machina_ who can be brought on thestage to solve difficulties scientific treatment is a farce. Thetranscendent element had appeared in a more subtle form through theinfluence of German philosophy. I noticed how Ranke is prone to referto ideas as if they were transcendent existences manifestingthemselves in the successive movements of history. It is intelligibleto speak of certain ideas as controlling, in a given period, --forinstance, the idea of nationality; but from the scientific point ofview, such ideas have no existence outside the minds of individualsand are purely psychical forces; and a historical "idea, " if it doesnot exist in this form, is merely a way of expressing a synthesis ofthe historian himself. 

15. From the more general influence of Darwinism on the place ofhistory in the system of human knowledge, we may turn to the influenceof the principles and methods by which Darwin explained development. It had been recognised even by ancient writers (such as Aristotle andPolybius) that physical circumstances (geography, climate) werefactors conditioning the character and history of a race or society. In the sixteenth century Bodin emphasised these factors, and manysubsequent writers took them into account. The investigations ofDarwin, which brought them into the foreground, naturally promotedattempts to discover in them the chief key to the growth ofcivilisation. Comte had expressly denounced the notion that thebiological methods of Lamarck could be applied to social man. Bucklehad taken account of natural influences, but had relegated them to asecondary plane, compared with psychological factors. But theDarwinian theory made it tempting to explain the development ofcivilisation in terms of "adaptation to environment, " "struggle forexistence, " "natural selection, " "survival of the fittest, " etc. [240]

The operation of these principles cannot be denied. Man is still ananimal, subject to zoological as well as mechanical laws. The darkinfluence of heredity continues to be effective; and psychicaldevelopment had begun in lower organic forms, --perhaps with lifeitself. The organic and the social struggles for existence aremanifestations of the same principle. Environment and climaticinfluence must be called in to explain not only the differentiation ofthe great racial sections of humanity, but also the varieties withinthese sub-species and, it may be, the assimilation of distinctvarieties. Ritter's _Anthropogeography_ has opened a useful line ofresearch. But on the other hand, it is urged that, in explaining thecourse of history, these principles do not take us very far, and thatit is chiefly for the primitive ultra-prehistoric period that they canaccount for human development. It may be said that, so far as concernsthe actions and movements of men which are the subject of recordedhistory, physical environment has ceased to act mechanically, and inorder to affect their actions must affect their wills first; and thatthis psychical character of the causal relations substantially altersthe problem. The development of human societies, it may be argued, derives a completely new character from the dominance of the consciouspsychical element, creating as it does new conditions (inventions, social institutions, etc. ) which limit and counteract the operation ofnatural selection, and control and modify the influence of physicalenvironment. Most thinkers agree now that the chief clews to thegrowth of civilisation must be sought in the psychological sphere. Imitation, for instance, is a principle which is probably moresignificant for the explanation of human development than naturalselection. Darwin himself was conscious that his principles had only avery restricted application in this sphere, as is evident from hiscautious and tentative remarks in the 5th chapter of his _Descent ofMan_. He applied natural selection to the growth of the intellectualfaculties and of the fundamental social instincts, and also to thedifferentiation of the great races or "sub-species" (Caucasian, African, etc. ) which differ in anthropological character. [241]

16. But if it is admitted that the governing factors which concern thestudent of social development are of the psychical order, thepreliminary success of natural science in explaining organic evolutionby general principles encouraged sociologists to hope that socialevolution could be explained on general principles also. The idea ofCondorcet, Buckle, and others, that history could be assimilated tothe natural sciences was powerfully reinforced, and the notion thatthe actual historical process, and every social movement involved init, can be accounted for by sociological generalisations, so-called"laws, " is still entertained by many, in one form or another. Dissentients from this view do not deny that the generalisations atwhich the sociologist arrives by the comparative method, by theanalysis of social factors, and by psychological deduction may be anaid to the historian; but they deny that such uniformities are laws orcontain an explanation of the phenomena. They can point to the elementof chance coincidence. This element must have played a part in theevents of organic evolution, but it has probably in a larger measurehelped to determine events in social evolution. The collision of twounconnected sequences may be fraught with great results. The suddendeath of a leader or a marriage without issue, to take simple cases, has again and again led to permanent political consequences. Moreemphasis is laid on the decisive actions of individuals, which cannotbe reduced under generalisations and which deflect the course ofevents. If the significance of the individual will had beenexaggerated to the neglect of the collective activity of the socialaggregate before Condorcet, his doctrine tended to eliminate asunimportant the roles of prominent men, and by means of thiselimination it was possible to found sociology. But it may be urgedthat it is patent on the face of history that its course hasconstantly been shaped and modified by the wills of individuals, [242]which are by no means always the expression of the collective will;and that the appearance of such personalities at the given moments isnot a necessary outcome of the conditions and cannot be deduced. Noris there any proof that, if such and such an individual had not beenborn, some one else would have arisen to do what he did. In some casesthere is no reason to think that what happened need ever have come topass. In other cases, it seems evident that the actual change wasinevitable, but in default of the man who initiated and guided it, itmight have been postponed, and, postponed or not, might have borne adifferent cachet. I may illustrate by an instance which has just comeunder my notice. Modern painting was founded by Giotto, and theItalian expedition of Charles VIII, near the close of the sixteenthcentury, introduced into France the fashion of imitating Italianpainters. But for Giotto and Charles VIII, French painting might havebeen very different. It may be said that "if Giotto had not appeared, some other great imitator would have played a role analogous to his, and that without Charles VIII there would have been the commerce withItaly, which in the long run would have sufficed to place France inrelation with Italian artists. But the equivalent of Giotto might havebeen deferred for a century and probably would have been different;and commercial relations would have required ages to produce the_rayonnement imitatif_ of Italian art in France, which the expeditionof the royal adventurer provoked in a few years. "[243] Instancesfurnished by political history are simply endless. Can we conjecturehow events would have moved if the son of Philip of Macedon had beenan incompetent? The aggressive action of Prussia which astonishedEurope in 1740 determined the subsequent history of Germany; but thataction was anything but inevitable; it depended entirely on thepersonality of Frederick the Great. 

Hence it may be argued that the action of individual wills is adetermining and disturbing factor, too significant and effective toallow history to be grasped by sociological formulae. The types andgeneral forms of development which the sociologist attempts todisengage can only assist the historian in understanding the actualcourse of events. It is in the special domains of economic history and_Culturgeschichte_ which have come to the front in modern times thatgeneralisation is most fruitful, but even in these it may be contendedthat it furnishes only partial explanations. 

17. The truth is that Darwinism itself offers the best illustration ofthe insufficiency of general laws to account for historicaldevelopment. The part played by coincidence, and the part played byindividuals--limited by, and related to, general socialconditions--render it impossible to deduce the course of the pasthistory of man or to predict the future. But it is just the same withorganic development. Darwin (or any other zoologist) could not deducethe actual course of evolution from general principles. Given anorganism and its environment, he could not show that it must evolveinto a more complex organism of a definite predetermined type; knowingwhat it has evolved into, he could attempt to discover and assign thedetermining causes. General principles do not account for a particularsequence; they embody necessary conditions; but there is a chapter ofaccidents too. It is the same in the case of history. 

18. Among the evolutional attempts to subsume the course of history undergeneral syntheses, perhaps the most important is that of Lamprecht, whose"kulturhistorische" attempt to discover and assign the determining causes. German history, exhibits the (indirect) influence of the Comtist school. Itis based upon psychology, which, in his views, holds among the sciences ofmind (_Geisteswissenschaften_) the same place (that of a_Grundwissenschaft_) which mechanics holds among the sciences of nature. History, by the same comparison, corresponds to biology, and, according tohim, it can only become scientific if it is reduced to general concepts(_Begriffe_). Historical movements and events are of a psychical character, and Lamprecht conceives a given phase of civilisation as "a collectivepsychical condition (_seelischer Gesamtzustand_)" controlling the period, "a diapason which penetrates all psychical phenomena and thereby allhistorical events of the time. "[244] He has worked out a series of suchphases, "ages of changing psychical diapason, " in his _DeutscheGeschichte_, with the aim of showing that all the feelings and actions ofeach age can be explained by the diapason; and has attempted to prove thatthese diapasons are exhibited in other social developments, and areconsequently not singular but typical. He maintains further that these agessucceed each other in a definite order; the principle being that thecollective psychical development begins with the homogeneity of all theindividual members of a society and, through heightened psychical activity, advances in the form of a continually increasing differentiation of theindividuals (this is akin to the Spencerian formula). This process, evolving psychical freedom from psychical constraint, exhibits a series ofpsychical phenomena which define successive periods of civilisation. Theprocess depends on two simple principles, that no idea can disappearwithout leaving behind it an effect or influence, and that all psychicallife, whether in a person or a society, means change, the acquisition ofnew mental contents. It follows that the new have to come to terms with theold, and this leads to a synthesis which determines the character of a newage. Hence the ages of civilisation are defined as the "highest conceptsfor subsuming without exception all psychical phenomena of the developmentof human societies, that is, of all historical events. "[245] Lamprechtdeduces the idea of a special historical science, which might be called"historical ethnology, " dealing with the ages of civilisation, and bearingthe same relation to (descriptive or narrative) history as ethnology toethnography. Such a science obviously corresponds to Comte's socialdynamics, and the comparative method, on which Comte laid so much emphasis, is the principal instrument of Lamprecht. 

19. I have dwelt on the fundamental ideas of Lamprecht, because theyare not yet widely known in England, and because his system is theablest product of the sociological school of historians. It carriesthe more weight as its author himself is a historical specialist, andhis historical syntheses deserve the most careful consideration. Butthere is much in the process of development which on such assumptionsis not explained, especially the initiative of individuals. Historicaldevelopment does not proceed in a right line, without the choice ofdiverging. Again and again, several roads are open to it, of which itchooses one--why? On Lamprecht's method, we may be able to assign theconditions which limit the psychical activity of men at a particularstage of evolution, but within those limits the individual has so manyoptions, such a wide room for moving, that the definition of thoseconditions, the "psychical diapasons, " is only part of the explanationof the particular development. The heel of Achilles in all historicalspeculations of this class has been the role of the individual. 

The increasing prominence of economic history has tended to encouragethe view that history can be explained in terms of general concepts ortypes. Marx and his school based their theory of human development onthe conditions of production, by which, according to them, all socialmovements and historical changes are entirely controlled. The leadingpart which economic factors play in Lamprecht's system is significant, illustrating the fact that economic changes admit most readily thiskind of treatment, because they have been less subject to direction orinterference by individual pioneers. 

Perhaps it may be thought that the conception of _social environment_(essentially psychical), on which Lamprecht's "psychical diapasons"depend, is the most valuable and fertile conception that the historianowes to the suggestion of the science of biology--the conception ofall particular historical actions and movements as (1) related to andconditioned by the social environment, and (2) gradually bringingabout a transformation of that environment. But no giventransformation can be proved to be necessary (predetermined). Andtypes of development do not represent laws; their meaning and valuelie in the help they may give to the historian, in investigating acertain period of civilisation, to enable him to discover theinter-relations among the diverse features which it presents. Theyare, as some one has said, an instrument of heuretic method. 

20. The man engaged in special historical researches--which have beenpursued unremittingly for a century past, according to scientificmethods of investigating evidence (initiated by Wolf, Niebuhr, Ranke)--have for the most part worked on the assumptions of genetichistory or at least followed in the footsteps of those who fullygrasped the genetic point of view. But their aim has been to collectand sift evidence, and determine particular facts; comparatively fewhave given serious thought to the lines of research and thespeculations which have been considered in this paper. They have beenreasonably shy of compromising their work by applying theories whichare still much debated and immature. But historiography cannotpermanently evade the questions raised by these theories. One mayventure to say that no historical change or transformation will befully understood until it is explained how social environment acted onthe individual components of the society (both immediately and byheredity), and how the individuals reacted upon their environment. Theproblem is psychical, but it is analogous to the main problem of thebiologist. 

FOOTNOTES:

[Footnote 238: A society presents suggestive analogies with anorganism, but it certainly is not an organism, and sociologists whodraw inferences from the assumption of its organic nature must fallinto error. A vital organism and a society are radically distinguishedby the fact that the individual components of the former, namely thecells, are morphologically as well as functionally differentiated, whereas the individuals which compose a society are morphologicallyhomogeneous and only functionally differentiated. The resemblances andthe differences are worked out in E. De Majewski's striking book, _LaScience de la Civilisation_. Paris. 1908. ]

[Footnote 239: It is to be observed that history is (not onlydifferent in scope but) not co-extensive with anthropology _in time_. For it deals only with the development of man in societies, whereasanthropology includes in its definition the proto-anthropic periodwhen _anthropos_ was still non-social, whether he lived in herds likethe chimpanzee, or alone like the male ourang-outang. (It has beenwell shown by Majewski that congregations--herds, flocks, packs, &c. --of animals are not _societies_; the characteristic of a societyis differentiation of function. Bee hives, ant hills, may be calledquasi-societies; but in their case the classes which perform distinctfunctions are morphologically different. )]

[Footnote 240: Recently O. Seeck has applied these principles to thedecline of Graeco-Roman civilisation in his _Untergang der antikenWelt_, 2 vols. , Berlin, 1895, 1901. ]

[Footnote 241: Darwinian formulae may be suggestive by way of analogy. For instance, it is characteristic of social advance that a multitudeof inventions, schemes and plans are framed which are never carriedout, similar to, or designed for the same end as, an invention or planwhich is actually adopted because it has chanced to suit better theparticular conditions of the hour (just as the works accomplished byan individual statesman, artist or savant are usually only a residueof the numerous projects conceived by his brain). This process inwhich so much abortive production occurs is analogous to eliminationby natural selection. ]

[Footnote 242: We can ignore here the metaphysical question offreewill and determinism. For the character of the individual's braindepends in any case on ante-natal accidents and coincidences, and soit may be said that the role of individuals ultimately depends onchance, --the accidental coincidence of independent sequences. ]

[Footnote 243: I have taken this example from G. Tarde's _La logiquesociale_ (p. 403), Paris, 1904, where it is used for quite a differentpurpose. ]

[Footnote 244: _Die kulturhistorische Methode_, Berlin, 1900, p. 26. ]

[Footnote 245: _Ibid. _ pp. 28, 29. ]

X

DARWINISM AND SOCIOLOGY

BY C. BOUGLÉ

_Professor of Social Philosophy in the University of Toulouse andDeputy-Professor at the Sorbonne, Paris_

How has our conception of social phenomena, and of their history, beenaffected by Darwin's conception of Nature and the laws of itstransformation? To what extent and in what particular respects havethe discoveries and hypotheses of the author of _The Origin ofSpecies_ aided the efforts of those who have sought to construct ascience of society?

To such a question it is certainly not easy to give any brief orprecise answer. We find traces of Darwinism almost everywhere. Sociological systems differing widely from each other have laid claimto its authority; while, on the other hand, its influence has oftenmade itself felt only in combination with other influences. TheDarwinian thread is worked into a hundred patterns along with otherthreads. 

To deal with the problem, we must, it seems, first of all distinguishthe more general conclusions in regard to the evolution of livingbeings, which are the outcome of Darwinism, from the particularexplanations it offers of the ways and means by which that evolutionis effected. That is to say, we must, as far as possible, estimateseparately the influence of Darwin as an evolutionist and Darwin as aselectionist. 

The nineteenth century, said Cournot, has witnessed a mighty effort to"réintégrer l'homme dans la nature. " From divers quarters there hasbeen a methodical reaction against the persistent dualism of theCartesian tradition, which was itself the unconscious heir of theChristian tradition. Even the philosophy of the eighteenth century, materialistic as were for the most part the tendencies of its leaders, seemed to revere man as a being apart, concerning whom laws might beformulated _à priori_. To bring him down from his pedestal there wasneeded the marked predominance of positive researches wherein noaccount was taken of the "pride of man. " There can be no doubt thatDarwin has done much to familiarise us with this attitude. Take forinstance the first part of _The Descent of Man_: it is an accumulationof typical facts, all tending to diminish the distance between us andour brothers, the lower animals. One might say that the naturalist hadhere taken as his motto, "Whosoever shall exalt himself shall beabased; and he that shall humble himself shall be exalted. " Homologousstructures, the survival in man of certain organs of animals, therudiments in the animal of certain human faculties, a multitude offacts of this sort, led Darwin to the conclusion that there is noground for supposing that the "king of the universe" is exempt fromuniversal laws. Thus belief in the _imperium in imperio_ has been, asit were, whittled away by the progress of the naturalistic spirit, itself continually strengthened by the conquests of the naturalsciences. The tendency may, indeed, drag the social sciences intooverstrained analogies, such, for instance, as the assimilation ofsocieties to organisms. But it will, at least, have had the merit ofhelping sociology to shake off the pre-conception that the groupsformed by men are artificial, and that history is completely at themercy of chance. Some years before the appearance of _The Origin ofSpecies_, August Comte had pointed out the importance, as regards theunification of positive knowledge, of the conviction that the socialworld, the last refuge of spiritualism, is itself subject todeterminism. It cannot be doubted that the movement of thought whichDarwin's discoveries promoted contributed to the spread of thisconviction, by breaking down the traditional barrier which cut man offfrom Nature. 

But Nature, according to modern naturalists, is no immutable thing: itis rather perpetual movement, continual progression. Their discoveriesbatter a breach directly into the Aristotelian notion of species; theyrefuse to see in the animal world a collection of immutable types, distinct from all eternity, and corresponding, as Cuvier said, to somany particular thoughts of the Creator. Darwin especiallycongratulated himself upon having been able to deal this doctrine the_coup de grâce_: immutability is, he says, his chief enemy; and he isconcerned to show--therein following up Lyell's work--that everythingin the organic world, as in the inorganic, is explained by insensiblebut incessant transformations. "Nature makes no leaps"--"Nature knowsno gaps": these two _dicta_ form, as it were, the two landmarksbetween which Darwin's idea of transformation is worked out. That isto say, the development of Darwinism is calculated to further theapplication of the philosophy of Becoming to the study of humaninstitutions. 

The progress of the natural sciences thus brings unexpectedreinforcements to the revolution which the progress of historicaldiscipline had begun. The first attempt to constitute an actualscience of social phenomena--that, namely, of the economists--hadresulted in laws which were called natural, and which were believed tobe eternal and universal, valid for all times and all places. But thisperpetuality, brother, as Knies said, of the immutability of the oldzoology, did not long hold out against the ever-swelling tide of thehistorical movement. Knowledge of the transformations that had takenplace in language, of the early phases of the family, of religion, ofproperty, had all favoured the revival of the Heraclitean view:πἁντα ρει̃. As to the categories of political economy, it wassoon to be recognised, as by Lasalle, that they too are onlyhistorical. The philosophy of history, moreover, gave expressionunder various forms to the same tendency. Hegel declares that "allthat is real is rational, " but at the same time he shows that all thatis real is ephemeral, and that for history there is nothing fixedbeneath the sun. It is this sense of universal evolution that Darwincame with fresh authority to enlarge. It was in the name of biologicalfacts themselves that he taught us to see only slow metamorphoses inthe history of institutions, and to be always on the outlook forsurvivals side by side with rudimentary forms. Anyone who reads_Primitive Culture_, by Tylor, --a writer closely connected withDarwin--will be able to estimate the services which these cardinalideas were to render to the social sciences when the age ofcomparative research had succeeded to that of _à priori_ construction. 

Let us note, moreover, that the philosophy of Becoming in passing throughthe Darwinian biology became, as it were, filtered; it got rid of thosetraces of finalism, which, under different forms, it had preserved throughall the systems of German Romanticism. Even in Herbert Spencer, it has beenplausibly argued, one can detect something of that sort of mysticconfidence in forces spontaneously directing life, which forms the veryessence of those systems. But Darwin's observations were preciselycalculated to render such an hypothesis futile. At first people may havefailed to see this; and we call to mind the ponderous sarcasms of Flourenswhen he objected to the theory of Natural Selection that it attributed tonature a power of free choice. "Nature endowed with will! That was thefinal error of last century; but the nineteenth no longer deals inpersonifications. "[246] In fact Darwin himself put his readers on theirguard against the metaphors he was obliged to use. The processes by whichhe explains the survival of the fittest are far from affording anyindication of the design of some transcendent breeder. Nor, if we lookclosely, do they even imply immanent effort in the animal; the sorting outcan be brought about mechanically, simply by the action of the environment. In this connection Huxley could with good reason maintain that Darwin'soriginality consisted in showing how harmonies which hitherto had beentaken to imply the agency of intelligence and will could be explainedwithout any such intervention. So, when later on, objective sociologydeclares that, even when social phenomena are in question, all finalistpreconceptions must be distrusted if a science is to be constituted, it isto Darwin that its thanks are due; he had long been clearing paths for itwhich lay well away from the old familiar road trodden by so many theoriesof evolution. 

This anti-finalist doctrine, when fully worked out, was, moreover, calculated to aid in the needful dissociation of two notions: that ofevolution and that of progress. In application to society these hadlong been confounded; and, as a consequence, the general idea seemedto be that only one type of evolution was here possible. Do we notdetect such a view in Comte's sociology, and perhaps even in HerbertSpencer's? Whoever, indeed, assumes an end for evolution is naturallyinclined to think that only one road leads to that end. But thosewhose minds the Darwinian theory has enlightened are aware that thetransformations of living beings depend primarily upon theirconditions, and that it is these conditions which are the agents ofselection from among individual variations. Hence, it immediatelyfollows that transformations are not necessarily improvements. Here, Darwin's thought hesitated. Logically his theory proves, as RayLankester pointed out, that the struggle for existence may have as itsoutcome degeneration as well as amelioration: evolution may beregressive as well as progressive. Then, too--and this is especiallyto be borne in mind--each species takes its good where it finds it, seeks its own path and survives as best it can. Apply this notion tosociety and you arrive at the theory of multilinear evolution. Divergencies will no longer surprise you. You will be forewarned notto apply to all civilisations the same measure of progress, and youwill recognise that types of evolution may differ just as socialspecies themselves differ. Have we not here one of the conceptionswhich mark off sociology proper from the old philosophy of history?

 * * * * *

But if we are to estimate the influence of Darwinism upon sociologicalconceptions, we must not dwell only upon the way in which Darwinimpressed the general notion of evolution upon the minds of thinkers. We must go into details. We must consider the influence of theparticular theories by which he explained the mechanism of thisevolution. The name of the author of _The Origin of Species_ has beenespecially attached, as everyone knows, to the doctrines of "naturalselection" and of "struggle for existence, " completed by the notion of"individual variation. " These doctrines were turned to account by verydifferent schools of social philosophy. Pessimistic and optimistic, aristocratic and democratic, individualistic and socialistic systemswere to war with each other for years by casting scraps of Darwinismat each other's heads. 

It was the spectacle of human contrivance that suggested to Darwin hisconception of natural selection. It was in studying the methods ofpigeon breeders that he divined the processes by which nature, in theabsence of design, obtains analogous results in the differentiation oftypes. As soon as the importance of artificial selection in thetransformation of species of animals was understood, reflectionnaturally turned to the human species, and the question arose, How fardo men observe, in connection with themselves, those laws of whichthey make practical application in the case of animals? Here we comeupon one of the ideas which guided the researches of Gallon, Darwin'scousin. The author of _Inquiries into Human Faculty and itsDevelopment_, [247] has often expressed his surprise that, consideringall the precautions taken, for example, in the breeding of horses, none whatever are taken in the breeding of the human species. It seemsto be forgotten that the species suffers when the "fittest" are notable to perpetuate their type. Ritchie, in his _Darwinism andPolitics_[248] reminds us of Darwin's remark that the institution ofthe peerage might be defended on the ground that peers, owing to theprestige they enjoy, are enabled to select as wives "the mostbeautiful and charming women out of the lower ranks. "[249] But, saysGalton, it is as often as not "heiresses" that they pick out, andbirth statistics seem to show that these are either less robust orless fecund than others. The truth is that considerations continue topreside over marriage which are entirely foreign to the improvement oftype, much as this is a condition of general progress. Hence theimportance of completing Odin's and De Candolle's statistics which aredesigned to show how characters are incorporated in organisms, howthey are transmitted, how lost, and according to what law eugenic, elements depart from the mean or return to it. 

But thinkers do not always content themselves with undertaking merelythe minute researches which the idea of Selection suggests. They areeager to defend this or that thesis. In the name of this idea certainsocial anthropologists have recast the conception of the process ofcivilisation, and have affirmed that Social Selection generally worksagainst the trend of Natural Selection. Vacher de Lapouge--followingup an observation by Broca on the point--enumerates the variousinstitutions, or customs, such as the celibacy of priests and militaryconscription, which cause elimination or sterilisation of the bearersof certain superior qualities, intellectual or physical. In a moregeneral way he attacks the democratic movement, a movement, as P. Bourget says, which is "anti-physical" and contrary to the naturallaws of progress; though it has been inspired "by the dreams of thatmost visionary of all centuries, the eighteenth. "[250] The "Equality"which levels down and mixes (justly condemned, he holds, by the Comtede Gobineau), prevents the aristocracy of the blond dolichocephalesfrom holding the position and playing the part which, in the interestsof all, should belong to them. Otto Ammon, in his _Natural Selectionin Man_, and in _The Social Order and its Natural Bases_, [251]defended analogous doctrines in Germany; setting the curverepresenting frequency of talent over against that of income, heattempted to show that all democratic measures which aim at promotingthe rise in the social scale of the talented are useless, if notdangerous; that they only increase the panmixia, to the greatdetriment of the species and of society. 

Among the aristocratic theories which Darwinism has thus inspired wemust reckon that of Nietzsche. It is well known that in order tocomplete his philosophy he added biological studies to hisphilological; and more than once in his remarks upon the _Wille zurMacht_ he definitely alludes to Darwin; though it must be confessedthat it is generally in order to proclaim the insufficiency of theprocesses by which Darwin seeks to explain the genesis of species. Nevertheless, Nietzsche's mind is completely possessed by an ideal ofSelection. He, too, has a horror of panmixia. The naturalists'conception of "the fittest" is joined by him to that of the "hero" ofromance to furnish a basis for his doctrine of the Superman. Let ushasten to add, moreover, that at the very moment when support wasbeing sought in the theory of Selection for the various forms of thearistocratic doctrine, those same forms were being battered down onanother side by means of that very theory. Attention was drawn to thefact that by virtue of the laws which Darwin himself had discoveredisolation leads to etiolation. There is a risk that the privilegewhich withdraws the privileged elements of Society from competitionwill cause them to degenerate. In fact, Jacoby in his _Studies inSelection, in connexion with Heredity in Man_, [252] concludes that"sterility, mental debility, premature death and, finally, theextinction of the stock were not specially and exclusively the fate ofsovereign dynasties; all privileged classes, all families inexclusively elevated positions share the fate of reigning families, although in a minor degree and in direct proportion to the loftinessof their social standing. From the mass of human beings springindividuals, families, races, which tend to raise themselves above thecommon level; painfully they climb the rugged heights, attain thesummits of power, of wealth, of intelligence, of talent, and then, nosooner are they there than they topple down and disappear in gulfs ofmental and physical degeneracy. " The demographical researches ofHansen[253] (following up and completing Dumont's) tended, indeed, toshow that urban as well as feudal aristocracies, burgher classes aswell as noble castes, were liable to become effete. Hence it mightwell be concluded that the democratic movement, operating as it doesto break down class barriers, was promoting instead of impeding humanselection. 

 * * * * *

So we see that, according to the point of view, very differentconclusions have been drawn from the application of the Darwinian ideaof Selection to human society. Darwin's other central idea, closelybound up with this, that, namely, of the "struggle for existence" alsohas been diversely utilised. But discussion has chiefly centered uponits signification. And while some endeavour to extend its applicationto everything, we find others trying to limit its range. Theconception of a "struggle for existence" has in the present day beentaken up into the social sciences from natural science, and adopted. But originally it descended from social science to natural. Darwin'slaw is, as he himself said, only Malthus' law generalised and extendedto the animal world: a growing disproportion between the supply offood and the number of the living is the fatal order whence arises thenecessity of universal struggle, a struggle which, to the greatadvantage of the species, allows only the best equipped individuals tosurvive. Nature is regarded by Huxley as an immense arena where allliving beings are gladiators. [254]

Such a generalisation was well adapted to feed the stream ofpessimistic thought; and it furnished to the apologists of war, inparticular, new arguments, weighted with all the authority which inthese days attaches to scientific deliverances. If people no longersay, as Bonald did, and Moltke after him, that war is a providentialfact, they yet lay stress on the point that it is a natural fact. Tothe peace party Dragomirov's objection is urged that its attempts arecontrary to the fundamental laws of nature, and that no sea wall canhold against breakers that come with such gathered force. 

But in yet another quarter Darwinism was represented as opposed tophilanthropic intervention. The defenders of the orthodox politicaleconomy found in it support for their tenets. Since in the organicworld universal struggle is the condition of progress, it seemedobvious that free competition must be allowed to reign unchecked inthe economic world. Attempts to curb it were in the highest degreeimprudent. The spirit of Liberalism here seemed in conformity with thetrend of nature: in this respect, at least, contemporary naturalism, offspring of the discoveries of the nineteenth century, broughtreinforcements to the individualist doctrine, begotten of thespeculations of the eighteenth: but only, it appeared, to turn mankindaway for ever from humanitarian dreams. Would those whom suchconclusions repelled be content to oppose to nature's imperativesonly the protests of the heart? There were some who declared, likeBrunetière, that the laws in question, valid though they might be forthe animal kingdom, were not applicable to the human. And so a returnwas made to the classic dualism. This indeed seems to be the line thatHuxley took, when, for instance, he opposed to the cosmic process anethical process which was its reverse. 

But the number of thinkers whom this antithesis does not satisfy growsdaily. Although the pessimism which claims authorisation from Darwin'sdoctrines is repugnant to them, they still are unable to accept thedualism which leaves a gulf between man and nature. And theirendeavour is to link the two by showing that while Darwin's lawsobtain in both kingdoms, the conditions of their application are notthe same: their forms, and, consequently, their results, vary with thevarying mediums in which the struggle of living beings takes place, with the means these beings have at disposal, with the ends even whichthey propose to themselves. 

Here we have the explanation of the fact that among determinedopponents of war partisans of the "struggle for existence" can befound: there are disciples of Darwin in the peace party. Novicow, forexample, admits the "_combat universel_" of which Le Dantec[255]speaks; but he remarks that at different stages of evolution, atdifferent stages of life the same weapons are not necessarilyemployed. Struggles of brute force, armed hand to hand conflicts, mayhave been a necessity in the early phases of human societies. Nowadays, although competition may remain inevitable andindispensable, it can assume milder forms. Economic rivalries, struggles between intellectual influences, suffice to stimulateprogress: the processes which these admit are, in the actual state ofcivilisation, the only ones which attain their end without waste, theonly ones logical. From one end to the other of the ladder of life, struggle is the order of the day; but more and more as the higherrungs are reached, it takes on characters which are proportionatelymore "humane. "

Reflections of this kind permit the introduction into the economicorder of limitations to the doctrine of "laisser faire, laisserpasser. " This appeals, it is said, to the example of nature wherecreatures, left to themselves, struggle without truce and withoutmercy; but the fact is forgotten that upon industrial battlefields theconditions are different. The competitors here are not left simply totheir natural energies: they are variously handicapped. A rich storeof artificial resources exists in which some participate and others donot. The sides then are unequal; and as a consequence the result ofthe struggle is falsified. "In the animal world, " said DeLaveleye, [256] criticising Spencer, "the fate of each creature isdetermined by its individual qualities; whereas in civilised societiesa man may obtain the highest position and the most beautiful wifebecause he is rich and well-born, although he may be ugly, idle orimprovident; and then it is he who will perpetuate the species. Thewealthy man, ill constituted, incapable, sickly, enjoys his riches andestablishes his stock under the protection of the laws. " Haycraft inEngland and Jentsch in Germany have strongly emphasised these"anomalies, " which nevertheless are the rule. That is to say that evenfrom a Darwinian point of view all social reforms can readily bejustified which aim at diminishing, as Wallace said, inequalities atthe start. 

But we can go further still. Whence comes the idea that all measuresinspired by the sentiment of solidarity are contrary to Nature'strend? Observe her carefully, and she will not give lessons only inindividualism. Side by side with the struggle for existence do we notfind in operation what Lanessan calls "association for existence. "Long ago, Espinas had drawn attention to "societies of animals, "temporary or permanent, and to the kind of morality that arose inthem. Since then, naturalists have often insisted upon the importanceof various forms of symbiosis. Kropotkin in _Mutual Aid_ has chosento enumerate many examples of altruism furnished by animals tomankind. Geddes and Thomson went so far as to maintain that "Each ofthe greater steps of progress is in fact associated with an increasedmeasure of subordination of individual competition to reproductive orsocial ends, and of interspecific competition to co-operative, association. "[257] Experience shows, according to Geddes, that thetypes which are fittest to surmount great obstacles are not so muchthose who engage in the fiercest competitive struggle for existence, as those who contrive to temper it. From all these observations thereresulted, along with a limitation of Darwinian pessimism, someencouragement for the aspirations of the collectivists. 

And Darwin himself would, doubtless, have subscribed to theserectifications. He never insisted, like his rival, Wallace, upon thenecessity of the solitary struggle of creatures in a state of nature, each for himself and against all. On the contrary, in _The Descent ofMan_, he pointed out the serviceableness of the social instincts, andcorroborated Bagehot's statements when the latter, applying laws ofphysics to politics, showed the great advantage societies derived fromintercourse and communion. Again, the theory of sexual evolution whichmakes the evolution of types depend increasingly upon preferences, judgments, mental factors, surely offers something to qualify whatseems hard and brutal in the theory of natural selection. 

But, as often happens with disciples, the Darwinians had out-DarwinedDarwin. The extravagances of social Darwinism provoked a usefulreaction; and thus people were led to seek, even in the animalkingdom, for facts of solidarity which would serve to justify humaneeffort. 

 * * * * *

On quite another line, however, an attempt has been made to connectsocialist tendencies with Darwinian principles. Marx and Darwin havebeen confronted; and writers have undertaken to show that the work ofthe German philosopher fell readily into line with that of the Englishnaturalist and was a development of it. Such has been the endeavour ofFerri in Italy and of Woltmann in Germany, not to mention others. Thefounders of "scientific socialism" had, moreover, themselves thoughtof this reconciliation. They make more than one allusion to Darwin inworks which appeared after 1859. And sometimes they use his theory todefine by contrast their own ideal. They remark that the capitalistsystem, by giving free course to individual competition, ends indeedin a _bellum omnium contra omnes_; and they make it clear thatDarwinism, thus understood, is as repugnant to them as to Dühring. 

But it is at the scientific and not at the moral point of view thatthey place themselves when they connect their economic history withDarwin's work. Thanks to this unifying hypothesis, they claim to haveconstructed--as Marx does in his preface to _Das Kapital_--a veritablenatural history of social evolution. Engels speaks in praise of hisfriend Marx as having discovered the true mainspring of history hiddenunder the veil of idealism and sentimentalism, and as havingproclaimed in the _primum vivere_ the inevitableness of the strugglefor existence. Marx himself, in _Das Kapital_, indicated anotheranalogy when he dwelt upon the importance of a general technology forthe explanation of this psychology:--a history of tools which would beto social organs what Darwinism is to the organs of animal species. And the very importance they attach to tools, to apparatus, tomachines, abundantly proves that neither Marx nor Engels were likelyto forget the special characters which mark off the human world fromthe animal. The former always remains to a great extent an artificialworld. Inventions change the face of its institutions. New modes ofproduction revolutionise not only modes of government, but modes evenof collective thought. Therefore it is that the evolution of societyis controlled by laws special to it, of which the spectacle of natureoffers no suggestion. 

If, however, even in this special sphere, it can still be urged thatthe evolution of the material conditions of society is in accord withDarwin's theory, it is because the influence of the methods ofproduction is itself to be explained by the incessant strife of thevarious classes with each other. So that in the end Marx, like Darwin, finds the source of all progress is in struggle. Both are grandsons ofHeraclitus:--πὁλεμος πατἠρ πἁντων. It sometimes happens, inthese days, that the doctrine of revolutionary socialism is contrastedas rude and healthy with what may seem to be the enervating tendencyof "solidarist" philanthropy: the apologists of the doctrine thenpride themselves above all upon their faithfulness to Darwinianprinciples. 

 * * * * *

So far we have been mainly concerned to show the use that socialphilosophies have made of the Darwinian laws for practical purposes:in order to orientate society towards their ideals each school triesto show that the authority of natural science is on its side. But evenin the most objective of theories, those which systematically makeabstraction of all political tendencies in order to study the socialreality in itself, traces of Darwinism are readily to be found. 

Let us take for example Durkheim's theory of Division of Labour. [258]The conclusions he derives from it are that whenever professionalspecialisation causes multiplication of distinct branches of activity, we get organic solidarity--implying differences--substituted formechanical solidarity, based upon likenesses. The umbilical cord, asMarx said, which connects the individual consciousness with thecollective consciousness is cut. The personality becomes more and moreemancipated. But on what does this phenomenon, so big withconsequences, itself depend? The author goes to social morphology forthe answer: it is, he says, the growing density of population whichbrings with it this increasing differentiation of activities. But, again, why? Because the greater density, in thrusting men up againsteach other, augments the intensity of their competition for the meansof existence; and for the problems which society thus has to facedifferentiation of functions presents itself as the gentlest solution. 

Here one sees that the writer borrows directly from Darwin. Competition is at its maximum between similars, Darwin had declared;different species, not laying claim to the same food, could moreeasily coexist. Here lay the explanation of the fact that upon thesame oak hundreds of different insects might be found. Other thingsbeing equal, the same applies to society. He who finds some unadoptedspecialty possesses a means of his own for getting a living. It is bythis division of their manifold tasks that men contrive not to crusheach other. Here we obviously have a Darwinian law serving asintermediary in the explanation of that progress of division of labourwhich itself explains so much in the social evolution. 

And we might take another example, at the other end of the series ofsociological systems. G. Tarde is a sociologist with the mostpronounced anti-naturalistic views. He has attempted to show that allapplication of the laws of natural science to society is misleading. In his _Opposition Universelle_ he has directly combatted all forms ofsociological Darwinism. According to him the idea that the evolutionof society can be traced on the same plan as the evolution of speciesis chimerical. Social evolution is at the mercy of all kinds ofinventions, which by virtue of the laws of imitation modify, throughindividual to individual, through neighbourhood to neighbourhood, thegeneral state of those beliefs and desires which are the only"quantities" whose variation matters to the sociologist. But, it maybe rejoined, that however psychical the forces may be, they are nonethe less subject to Darwinian laws. They compete with each other; theystruggle for the mastery of minds. Between types of ideas, as betweenorganic forms, selection operates. And though it may be that thesetypes are ushered into the arena by unexpected discoveries, we yetrecognise in the psychological accidents, which Tarde places at thebase of everything, near relatives of those small accidentalvariations upon which Darwin builds. Thus, accepting Tarde's ownrepresentations, it is quite possible to express in Darwinian terms, with the necessary transpositions, one of the most idealisticsociologies that have ever been constructed. 

These few examples suffice. They enable us to estimate the extent ofthe field of influence of Darwinism. It affects sociology not onlythrough the agency of its advocates but through that of its opponents. The questions to which it has given rise have proved no less fruitfulthan the solutions it has suggested. In short, few doctrines, in thehistory of social philosophy, will have produced on their passage afiner crop of ideas. 

FOOTNOTES:

[Footnote 246: P. Flourens, _Examen du Livre de M. Darwin surl'Origine des Espèces_, p. 53, Paris, 1864. See also Huxley, "Criticisms on the _Origin of Species, " Collected Essays_, Vol. II, p. 102, London, 1902. ]

[Footnote 247: _Inquiries into Human Faculty_, pp. 1, 2, 3 sq. , London, 1883. ]

[Footnote 248: _Darwinism and Politics_, pp. 9, 22, London, 1889. ]

[Footnote 249: _Life and Letters of Charles Darwin_, II. P. 385. ]

[Footnote 250: V. De Lapouge, _Les Sélections sociales_, p. 259, Paris, 1896. ]

[Footnote 251: _Die natärliche Auslese beim Menschen_, Jena, 1893; _DuGesellschaftsordnung und ihre natürlichen Grundlagen. Entwurf einerSozialanthropologie_, Jena, 1896. ]

[Footnote 252: _Etudes sur la Sélection dans ses rapports avecl'hérédité chez l'homme_, Paris, p. 481, 1881. ]

[Footnote 253: _Die drei Bevölkerungsstufen_, Munich, 1889. ]

[Footnote 254: _Evolution and Ethics_, p. 200; _Collected Essays_, Vol. IX, London, 1894. ]

[Footnote 255: _Les Luttes entre Sociétés humaines et leurs phasessuccessives_, Paris, 1893. ]

[Footnote 256: _Le socialisme contemporain_, p. 384 (6th edit. ), Paris, 1891. ]

[Footnote 257: Geddes and Thomson, _The Evolution of Sex_, p. 311, London, 1889. ]

[Footnote 258: _De la Division du Travail social_, Paris. 1893. ]

INDEX

_Abraxas grossulariata_, 100

Acquired characters, transmission of, 20, 28, 42, 94, 120, 149, 171, 173

_Acraea johnstoni_, 290[Transcriber's Note: No such page number or reference seen]

Adaptation, 24, 27, 34, 39, 42-45, 50, 58, 79-86, 106, 107

Adloff, 140

Alexander, 217

Ameghino, 132, 138

Ammon, O. , Works of, 271

_Anaea divina_, 69

Anglicus, Bartholomaeus, 237

Ankyroderma, 40

Anomma, 44

Anthropops, 132

Ants, modifications of, 43-46, 51

Ardigò, 207, 208

Argyll, Huxley and the Duke of, 238

Aristotle, 3, 237, 240

Avenarius, 211

Bacon, on mutability of species, 4, 5

Baehr, von, on Cytology, 99

Bain, 194

Baldwin, J. M. , 53, Foot Note 165

Balfour, A. J. , 241

Barratt, 217

Bates, H. W. , on Mimicry, 70, 76 --232

BATESON, W. , on _Heredity andVariation in Modern Lights_, 87-110 --on discontinuous evolution, 30

Bathmism, 14

Bells (Sir Charles) _Anatomy of Expression_, 177

Bentham, Jeremy, 217, 218

Bergson, H. , 208

Berkeley, 200

Berthelot, 228

Bickford, E. , experiments on degeneration by, 52

Biophores, 47

Blumenbach, 89

Bodin, 256

Bonald, on war, 273

Bonnet, 6

BOUGLÉ, C. , on _Darwinism and Sociology_, 264-280

Bourdeau, 253

Bourget, P. , 270

Boutroux, 208

Brassica, hybrids of, 106

_Brassica Napus_, 106

Broca, 137, 270

Brock, on Kant, Foot Note 6

Brunetière, 274

Bruno, on Evolution, 4

Buch, von, 15

Buckle, 252, 253, 256, 258

Buffon, 6-15, 21, 88

Burdon-Sanderson, J. , letter from, Foot Note 224

BURY, J. B. , on _Darwinism and History_, 246-263

Butler, Samuel, 9, Foot Note 17, Foot Note 57, Foot Note 61, 94, Foot Note 66, 107

Butterflies, mimicry in, 65-83 --sexual characters in, 59-63

Cabanis, 201

Candolle, de, 270

Carneri, 217

_Castnia linus_, 76

Caterpillars, variation in, 36, 37

Cesnola, experiments on Mantis by, 65

Chaerocampa, colouring of, 68

Chambers, R. , _The Vestiges of Creation_ by, 15

Chromosomes and Chromomeres, 47, 96-100

Chun, Foot Note 36

Claus, Foot Note 21

Clodd, E. , Foot Note 13

Coadaptation, 41-54

_Colobopsis truncata_, 44

Colour, E. B. Poulton, in relation to Sexual Selection, 61-65

Comte, A. , 200-203, 252-255, 262, 265

Condorcet, 221, 250, 252, 258

Cope, 138

Correlation of organisms, Darwin's idea of the, 2

Cournot, 265

Cuvier, 9, 10, 266, 268

Cytology and heredity, 95, 96, 99, 100

_Danaida chrysippus_, 75

_Danaida genutia_, 75

_D. Plexippus_, 75

Dantec, Le, 274

Darwin, Charles, as an Anthropologist, 146-165 --on ants, 44 --and S. Butler, Foot Note 61, 94 --on Cirripedia, 212 --on the Descent of Man, 111-145 --evolutionist authors referred to in the _Origin_ by, 9

Darwin, Charles, and Haeckel, 137 --and History, 246-263 --and Huxley, 112 --on Lamarck, 28, 129 --on Language, 124 --and Malthus, 16, 24, 91 --on Patrick Matthew, 19 --on mental evolution, 166-196 --on Natural Selection, 21, 41, 54, 55, 122 --a "Naturalist for Naturalists, " 87 --his personality, 187 --his influence on Philosophy, 197-222 --predecessors of, 1-22 --his views on religion, etc. , 115, 116, 219-222 --his influence on religious thought, 223-245 --causes of his success, 10, 90

Darwin, Charles, on the _Vestiges of Creation_, 15 --and Wallace, 23, 183 --on evolution, 7-15, 88 --on Lamarckism, 11

Darwin, F. , on Prichard's "Anticipations, " 21

Darwinism, Sociology, Evolution and, 17-18

Degeneration, 49-51, 93

Deniker, 137

Descartes, 4

Descent, history of doctrine of, 1

_Descent of Man_, G. Schwalbe on _The_, 111-145 --rejection in Germany of _The_, 156

Diderot, 6, 198

Dimorphism, seasonal, 30

_Dismorphia orise_, 75

Dragomirov, 273

Driesch, Foot Note 67

Dryopithecus, 132

Dubois, E. , on Pithecanthropus, 132, 137

Dühring, 214, 277

Duns Scotus, 200

Duret, C. , 6

Durkheim, on division of labour, 278

Ecology, Foot Note 205

Eimer, 109

_Elymnias undularis_, 73, 75

Embryology, the Origin of Species and, 154, 155

Empedocles, 3, 27, 151

Engels, 277

Environment, action of, 12, 13, 15

Epicurus, a poet of Evolution, 4

Eristalis, 75

Espinas, 275

Evolution, and creation, 233 --conception of, 3-5, 9, 148, 151, 198 --discontinuous, 30 --experimental, 5, 7 --factors of, 11-15 --mental, 194 --Lloyd Morgan on mental factors in, 166-196 --Darwinism and Social, 18 --Saltatory, 29-32 --Herbert Spencer on, 204-207 --Philosophers and modern methods of studying, 4

Expression of the Emotions, 177-184

Ferri, 277

Ferrier, his work on the brain, 523[Transcriber's note: No such page number or reference seen]

Fichte, 222

Flourens, 267

Flowers and Insects, 61, 78

Fouillée, 207, 208

Fraipont, on skulls from Spy, 134

GADOW, 162

_Gallus bankiva_, 102

Gallon, F. , 125, 150, 269

Geddes, P. , 17, Foot Note 32

Geddes, P. And A. W. Thomson, 276

Gegenbaur, 150, 163

Genetics, 93, 96

_Germ-plasm_, continuity of, 95--Weismann on, 46-51

Germinal Selection, 36, 37, 46-51, 64

Gibbon, 248

Giuffrida-Ruggeri, 138, 140

Giotto, 259

Gizycki, 217

Goethe and Evolution, 8, 14, 15, 201--on the relation between Man and Mammals, 161, 163--221

Gore, Dr. , 226

Gorjanovič-Kramberger, 134

Gosse, P. H. , 234

_Grapta C. Album_, 69

Groos, 187, 188

Gulick, 15, 53

Guyau, 217

Haberlandt, G. , 34

HAECKEL, E. , on _Charles Darwin as an Anthropologist_, 146-165 --and Darwin, 135-151, 137, 146-165 --on the Descent of Man, 137, 143 --on Lamarck, 8, Foot Note 21 --a leader in the Darwinian controversy, 137 --217

Häcker, 33

Hansen, 272

Hartmann, von, 240

Harvey, 4

Haycraft, 275

Hegel, 201, 203, 215, 251, 252, 255

Heraclitus, 278

Herder, 4, 5, 20

Heredity and Cytology, 95, 96 --Haeckel on, 147, 148, 149, 153 --and Variation, 87-110 --219, 224

Hering, E. , on Memory, 153

Hertwig, O. , 150

History, Darwin and, 246-263

Hobbes, T. , 200, 215

Hobhouse, 242

HÖFFDING, H. , on _The Influence of the Conception of Evolution on Modern Philosophy_, 197-222

Holothurians, calcareous bodies in skin of, 37-41

_Homo heidelbergensis_, Foot Note 118

_H. Neandertalensis_, 138

_H. Pampaeus_, 144

_H. Primigenius_, 133, 134, 138, 144

_Homunculus_, 132

Hooker, Sir J. D. , and Darwin, 23, 116

Huber, 170

Hügel, F. Von, Foot Note 221

Hume, 200

Hutcheson, 216

Huxley, T. H. , and Darwin, 112, 116, 268 --and the Duke of Argyll, 238 --on Lamarck, 89 --on Man, 111, 112, 137, 146, 156, 160, 163 --on Selection, 24, 91 --on transmission of acquired characters, 149 --14, 24, 104, 231-236, 273, 274

Hybrids, Sterility of, 104, 105, 106

Inheritance of acquired characters, 93, 94

Insects and Flowers, 60, 61, 78, 79

Instinct, 122, 172-175

Irish Elk, an example of coadaptation, 41, 42, 45

Jacoby, _Studies in Selection_ by, 272

James, W. , 180, 191, 211

Jentsch, 275

Kallima, protective colouring of, 35, 68, 70

_K. Inachis_, 68

Kammerer's experiments on Salamanders, 28

Kant, I. , 4, 5, 6, 27, 198, 211, 212, 217, 221, 222

Keane, on the Primates, 138

Keith, on Anthropoid Apes, 138

Kepler, 198

Klaatsch, on Ancestry of Man, 140

Klaatsch and Hauser, 134

Knies, 266

Kölliker, his views on Evolution, 29, 150

Kollmann, on origin of human races, 144

Korschinsky, 31

Krause, E. , Foot Note 10, 13

Kropotkin, 214, 275

Lamarck, his division of the Animal Kingdom, 160, 161 --Darwin's opinion of, 129 --on Evolution, 9-14, 21, 25, 171, 172, 173, 179, 180, 201, 202, 253 --on Man, 146, 148, 160, 163 --89, 109, 201, 202, 233

Lamarckian principle, 28, 41-44, 50-54, 67, 84, 86

Lamb, C. , 229

Lamettrie, 198

Lamprecht, 260-263

Lanessan, J. L. De, Foot Note 17, 275

Lang, Foot Note 21

Lange, 180

Language, Darwin on, 123, 124 --Evolution and the Science of, 178, 179, 188

Lankester, Sir E. Ray, on degeneration, 268 --on educability, 170, 189

Lankester, Sir E. Ray, on the germ-plasm theory, 150

Lapouge, Vacher de, 270

Lartet, M. E. , 189

Lasalle, 266

Laveleye, de, 275

Lawrence, W. , 89, Foot Note 65

Lehmann-Nitsche, 138, 144

Leibnitz, 4, 5, 213

Lepidoptera, variation in, 37, 60-63

Lessing, 4, 221

Liddon, H. P. , 234

_Limenitis archippus_, 74

Linnaeus, 6

Locy, W. A. , Foot Note 15

Lovejoy, Foot Note 56

Lubbock, 125

Lucretius, a poet of Evolution, 4

Lyell, Sir Charles, and Darwin, 23, 116 --the uniformitarian teaching of, 89

Macacus, ear of, 119

Mach, E. , 153, 211

Mahoudeau, 137

Maillet, de, 6

Majewski, Foot Note 238, Foot Note 239

Malthus, his influence on Darwin, 16-18, 21, 24, 91 --200, 273

Man, Descent of, 126, 127, 128, 131-145, 156-165, 189, 254, 265 --mental and moral qualities of animals and, 122-126, 164, 188-192 --pre-Darwinian views on the Descent of, 1

Man, Tertiary flints worked by, 136

_Man_, G. Schwalbe on Darwin's _Descent of_, 111-145

Manouvrier, 137

_Mantis religiosa_, colour experiments on, 65, 68

Marx, 262, 276-278

Matthew, P. , and Natural Selection, 18, 19

Maupertuis, 6, 88, 103

Mayer, R. , 197

_Mechanitis lysimnia_, 77

_Melinaea ethra_, 77

Mendel, 97-100, 184, 228

Merz, J. T. , Foot Note 14

Mesopithecus, 132

Mill, J. S. , 193, 200, 202, 218

Mimicry, 70-82

Moltke, on war, 273

Monkeys, fossil, 132

Montesquieu, 248

Monticelli, 155

MORGAN, C. LLOYD, on _Mental Factors in Evolution_, 166-196 --on Organic Selection, 53

Morgan, T. H. , 99

Morselli, 138

Mortillet, 136

Moseley, Foot Note 224

Muller, Fritz, _Für Darwin_ by, 154 --on Mimicry, 233 --59, 77

Muller, J. , 147

Müller, Max, on language, 124

Mutation, 15, 31, 184, 199, 209

Nägeli, 109, 151, 153

Nathusius, 103

Natural Selection, Darwin's views on, 90, 91, 122, 149 --Darwin and Wallace on, 2, 163, 183 --and design, 241, 242 --and educability, 195 --and human development, 125, 256, 257 --16-20, 25, 26, 41, 55-58, 64-86, 87-96, 199, 233

Neandertal skulls, 133, 134

Neodarwinism, 150

Newton, A. , Foot Note 59

Newton, I. , 197, 198

Niebuhr, 249, 263

Nietzsche, 214, 271

Nitsche, 119

Novicow, 274

Nuttall, G. H. F. , 135

Occam, 200

Odin, 270

Oecology, see Ecology

_Oenothera lamarckiana_, 32

Oestergren, on Holothurians, 37-39

Oken, L. , 7, 201

Organic Selection, 53, 54, 172, 173

Orthogenesis, 109

Osborn, H. F. , 53, Foot Note 165 --_From the Greeks to Darwin_ by, 3-5, 12, 14, 20

_Ovibos moschatus_, 67

Owen, Sir Richard, 111

Packard, A. S. , Foot Note 12, Foot Note 18

Palaeopithecus, 132

Paley, 18, 242, 244

Panmixia, Weismann's principle of, 54

_Papilio dardanus_, 72, 73, 74

_P. Meriones_, 73

_P. Merope_, 72

Pearson, K. , Foot Note 7

Penck, 136

Peridineae, 33

Perrier, E. , Foot Note 21, 20

Perthes, B. De, 123

Pfeffer, W. , 28

Philosophy, influence of the conception of evolution on modern, 197-222

Pithecanthropus, 133, 134, 138, 143

Pitheculites, 144

Plate, Foot Note 37

Pliopithecus, 132

Pouchet, G. , Foot Note 3

POULTON, E. B. , experiments on Butterflies by, 65 --on J. C. Prichard, 20 --on Mimicry, 69, 71, 75, 78 --Foot Note 34, Foot Note 43, Foot Note 49, Foot Note 55

Prichard, J. C. , 20, 21, 89, Foot Note 65

_Pronuba yuccasella_, 79

Protective resemblance, 65-70

Pusey, 115

Quatrefages, A. De, Foot Note 21, 19

Radiolarians, 33

Ranke, 249, 251, 255, 263

Rau, A. , 153

Ray, J. , 4

Regeneration, Foot Note 71

Religious thought, Darwin's influence on, 223-245

Reversion, 120, 121

Ridley, H. N. , Foot Note 88

Ritchie, 270

Robinet, 6

Rolph, 217

Romanes, G. J. , Foot Note 3, 15, 32, 54, 164, 234

Roux, 151, 152

Ruskin, 230

Rutot, 136

Saint-Hilaire, E. G. De, 8, 15, 20

Saltatory Evolution, 29-32 (see also Mutations)

Sanders, experiments on Vanessa by, 65

Savigny, 249

Schelling, 4, 5, 200, 201

Schleiden and Schwann, Cell-theory of, 147

Schoetensack, on _Homo heidelbergensis_, Foot Note 118

Schütt, 23

SCHWALBE, G. , on _The Descent of Man_, 111-145

Seeck, O. , Foot Note 240

Segregation, 97, 98

Selection, artificial, 24, 25, 26, 41, 45, 120, 269-272 --germinal, 35, 36, 46-52, 64

Selection, natural (see Natural Selection) --organic, 53, 171, 172 --sexual, 55-64, 117, 118 --social and natural, 271 --23-86, 103, 129, 130

Selenka, 131

Semnopithecus, 132

Semon, R. , 28, 153

Sergi, 138, 143

Sex, recent investigations on, 99, 100

Sibbern, 201

_Smerinthus ocellata_, 38

_Smerinthus populi_, 38

_S. Tiliae_, 38

Smith, A. , 200

Sociology, Darwinism and, 264-280 --History and, 255

Sollas, W. J. , 134

Sorley, W. R. , 217

Species and varieties, 100

Spencer, H. , on evolution, 204-209 --on the theory of Selection, 41

Spencer, H. , on Sociology, 268 --on the transmission of acquired characters, 149 --on Weismann, 41, 150 --2, 17, 217, 231, 268

Sphingidae, variation in, 37

Spinoza, 153, 206

Standfuss, 82

Stephen, L. , 217

Sterility in hybrids, 104-106

Sterne, C, Foot Note 10

Struggle for existence, 25, 26, 272-274

Sutton, A. W. , Foot Note 73

Synapta, calcareous bodies in skin of, 38-41

Syrphus, 75

Tarde, G. , 279

Tennant, F. R. , Foot Note 218

Tetraprothomo, 138, 144

THOMSON, J. A. , on _Darwin's Predecessors_, 1-22 --150 --and P. Geddes, 276

Treschow, 201

Treviranus, 8, 14, 15

Turgot, 249

Turner, Sir W. , 150

Tylor, 267

Tyndall, W. , 267

Tyrrell, G, Foot Note 222

Uhlenhuth, on blood reactions, 135

Use and disuse, 28, 41-43, 48-54, 94, 95, 119, 149

Vanessa, 63

_V. Levana_, 31

_V. Polychloros_, 82

_V. Urticae_, 65, 82

Variability, Darwin's attention directed to, 24 --W. Bateson on, 87-110 --causes of, 200

Variation, Darwin's views as an evolutionist, and as a systematist, on, 212 --and heredity, 87-110 --minute, 28-32 --in relation to species, 100, 101

Varigny, H. De, 6, 19

Verworn, 136

_Vestiges of Creation_, Darwin on _The_, 15

Virchow, his opposition to Darwin, 157, 158 --on the transmission of acquired characters, 149

Vogt, 137

Voltaire, 248

VRIES, H. De, the Mutation theory of, 31, 101, 151, 213

WAGGETT, Rev. P. N. , on _The Influence of Darwin upon Religious Thought_, 223-245

Wallace, A. R. , on Colour, 63, 71 --and Darwin, Foot Note 7, 23, 183 --on the Descent of Man, 116 --on Malthus, 17 --on Natural Selection, 2, 16, 163, 232

Wallace, A. R. , on social reforms, 275, 276 --on Sexual Selection, 183, 184

Walton, 237

Watt, J. , and Natural Selection, 21

WEISMANN, A. , on _The Selection Theory_, 23-86 --his germ-plasm theory, 46-51, 149, 150 --and Prichard, 20 --and Spencer, 42

Weismann, A. , on the transmission of acquired characters, 93-95 --156

Wells, W. C, and Natural Selection, 18

White, G. , 3

Williams, C. M. , 217

Wilson, E. B. , on cytology, 99

Wolf, 249

Wollaston's, T. V. , _Variation of Species_, Foot Note 59

Woltmann, 277

Woolner, 118

Wundt, on language, 207, 208

_Xylina vetusta_, 82

Yucca, fertilisation of, 78, 79

Zeller, E. , Foot Note 3

_Zoonomia_, Erasmus Darwin's, 7

 * * * * *

_The publishers will be pleased to send, upon request, an illustratedcatalogue setting forth the purposes and ideals of The Modern Library, and describing in detail each volume in the series. Every reader ofbooks will find titles he has been looking for, attractively printed, and at an unusually low price. _

 * * * * *