ON THE STUDY OF ZOOLOGY

by Thomas H. Huxley

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NATURAL HISTORY is the name familiarly applied to the study of theproperties of such natural bodies as minerals, plants, and animals; thesciences which embody the knowledge man has acquired upon these subjectsare commonly termed Natural Sciences, in contradistinction to otherso-called "physical" sciences; and those who devote themselvesespecially to the pursuit of such sciences have been and are commonlytermed "Naturalists. "

Linnaeus was a naturalist in this wide sense, and his 'Systema Naturae'was a work upon natural history, in the broadest acceptation of theterm; in it, that great methodising spirit embodied all that was knownin his time of the distinctive characters of minerals, animals, and plants. But the enormous stimulus which Linnaeus gave to theinvestigation of nature soon rendered it impossible that any one manshould write another 'Systema Naturae, ' and extremely difficult for anyone to become even a naturalist such as Linnaeus was. 

Great as have been the advances made by all the three branches ofscience, of old included under the title of natural history, there canbe no doubt that zoology and botany have grown in an enormously greaterratio than mineralogy; and hence, as I suppose, the name of "naturalhistory" has gradually become more and more definitely attached to theseprominent divisions of the subject, and by "naturalist" people havemeant more and more distinctly to imply a student of the structure andfunction of living beings. 

However this may be, it is certain that the advance of knowledgehas gradually widened the distance between mineralogy and its oldassociates, while it has drawn zoology and botany closer together; sothat of late years it has been found convenient (and indeed necessary)to associate the sciences which deal with vitality and all its phenomenaunder the common head of "biology"; and the biologists have cometo repudiate any blood-relationship with their foster-brothers, themineralogists. 

Certain broad laws have a general application throughout both the animaland the vegetable worlds, but the ground common to these kingdoms ofnature is not of very wide extent, and the multiplicity of details is sogreat, that the student of living beings finds himself obliged to devotehis attention exclusively either to the one or the other. If he electsto study plants, under any aspect, we know at once what to call him. Heis a botanist, and his science is botany. But if the investigation ofanimal life be his choice, the name generally applied to him will varyaccording to the kind of animals he studies, or the particular phenomenaof animal life to which he confines his attention. If the study ofman is his object, he is called an anatomist, or a physiologist, or anethnologist; but if he dissects animals, or examines into the mode inwhich their functions are performed, he is a comparative anatomist orcomparative physiologist. If he turns his attention to fossil animals, he is a palaeontologist. If his mind is more particularly directedto the specific description, discrimination, classification, anddistribution of animals, he is termed a zoologist. 

For the purpose of the present discourse, however, I shall recognisenone of these titles save the last, which I shall employ as theequivalent of botanist, and I shall use the term zoology as denotingthe whole doctrine of animal life, in contradistinction to botany, whichsignifies the whole doctrine of vegetable life. 

Employed in this sense, zoology, like botany, is divisible intothree great but subordinate sciences, morphology, physiology, anddistribution, each of which may, to a very great extent, be studiedindependently of the other. 

Zoological morphology is the doctrine of animal form or structure. Anatomy is one of its branches; development is another; whileclassification is the expression of the relations which differentanimals bear to one another, in respect of their anatomy and theirdevelopment. 

Zoological distribution is the study of animals in relation to theterrestrial conditions which obtain now, or have obtained at anyprevious epoch of the earth's history. 

Zoological physiology, lastly, is the doctrine of the functions oractions of animals. It regards animal bodies as machines impelled bycertain forces, and performing an amount of work which can be expressedin terms of the ordinary forces of nature. The final object ofphysiology is to deduce the facts of morphology, on the one hand, andthose of distribution on the other, from the laws of the molecularforces of matter. 

Such is the scope of zoology. But if I were to content myself with theenunciation of these dry definitions, I should ill exemplify thatmethod of teaching this branch of physical science, which it is my chiefbusiness to-night to recommend. Let us turn away then from abstractdefinitions. Let us take some concrete living thing, some animal, thecommoner the better, and let us see how the application of common senseand common logic to the obvious facts it presents, inevitably leads usinto all these branches of zoological science. 

I have before me a lobster. When I examine it, what appears to be themost striking character it presents? Why, I observe that this part whichwe call the tail of the lobster, is made up of six distinct hard ringsand a seventh terminal piece. If I separate one of the middle rings, saythe third, I find it carries upon its under surface a pair of limbs orappendages, each of which consists of a stalk and two terminal pieces. So that I can represent a transverse section of the ring and itsappendages upon the diagram board in this way. 

If I now take the fourth ring, I find it has the same structure, and sohave the fifth and the second; so that, in each of these divisions ofthe tail, I find parts which correspond with one another, a ring andtwo appendages; and in each appendage a stalk and two end pieces. Thesecorresponding parts are called, in the technical language of anatomy, "homologous parts. " The ring of the third division is the "homologue" ofthe ring of the fifth, the appendage of the former is the homologueof the appendage of the latter. And, as each division exhibitscorresponding parts in corresponding places, we say that all thedivisions are constructed upon the same plan. But now let us considerthe sixth division. It is similar to, and yet different from, theothers. The ring is essentially the same as in the other divisions; butthe appendages look at first as if they were very different; and yetwhen we regard them closely, what do we find? A stalk and two terminaldivisions, exactly as in the others, but the stalk is very short andvery thick, the terminal divisions are very broad and flat, and one ofthem is divided into two pieces. 

I may say, therefore, that the sixth segment is like the others in plan, but that it is modified in its details. 

The first segment is like the others, so far as its ring is concerned, and though its appendages differ from any of those yet examined in thesimplicity of their structure, parts corresponding with the stem and oneof the divisions of the appendages of the other segments can be readilydiscerned in them. 

Thus it appears that the lobster's tail is composed of a series ofsegments which are fundamentally similar, though each presents peculiarmodifications of the plan common to all. But when I turn to the forepartof the body I see, at first, nothing but a great shield-like shell, called technically the "carapace, " ending in front in a sharp spine, oneither side of which are the curious compound eyes, set upon the ends ofstout movable stalks. Behind these, on the under side of the body, aretwo pairs of long feelers, or antennae, followed by six pairs of jawsfolded against one another over the mouth, and five pairs of legs, theforemost of these being the great pinchers, or claws, of the lobster. 

It looks, at first, a little hopeless to attempt to find in this complexmass a series of rings, each with its pair of appendages, such as I haveshown you in the abdomen, and yet it is not difficult to demonstratetheir existence. Strip off the legs, and you will find that each pair isattached to a very definite segment of the under wall of the body; butthese segments, instead of being the lower parts of free rings, as inthe tail, are such parts of rings which are all solidly united andbound together; and the like is true of the jaws, the feelers, and theeye-stalks, every pair of which is borne upon its own special segment. Thus the conclusion is gradually forced upon us, that the body of thelobster is composed of as many rings as there are pairs of appendages, namely, twenty in all, but that the six hindmost rings remain free andmovable, while the fourteen front rings become firmly soldered together, their backs forming one continuous shield--the carapace. 

Unity of plan, diversity in execution, is the lesson taught by the studyof the rings of the body, and the same instruction is given still moreemphatically by the appendages. If I examine the outermost jaw I find itconsists of three distinct portions, an inner, a middle, and an outer, mounted upon a common stem; and if I compare this jaw with the legsbehind it, or the jaws in front of it, I find it quite easy to see, that, in the legs, it is the part of the appendage which correspondswith the inner division, which becomes modified into what we knowfamiliarly as the "leg, " while the middle division disappears, and theouter division is hidden under the carapace. Nor is it more difficult todiscern that, in the appendages of the tail, the middle division appearsagain and the outer vanishes; while, on the other hand, in the foremostjaw, the so-called mandible, the inner division only is left; and, inthe same way, the parts of the feelers and of the eye-stalks can beidentified with those of the legs and jaws. 

But whither does all this tend? To the very remarkable conclusion thata unity of plan, of the same kind as that discoverable in the tail orabdomen of the lobster, pervades the whole organization of its skeleton, so that I can return to the diagram representing any one of the rings ofthe tail, which I drew upon the board, and by adding a third division toeach appendage, I can use it as a sort of scheme or plan of any ring ofthe body. I can give names to all the parts of that figure, and then ifI take any segment of the body of the lobster, I can point out toyou exactly, what modification the general plan has undergone in thatparticular segment; what part has remained movable, and what has becomefixed to another; what has been excessively developed and metamorphosedand what has been suppressed. 

But I imagine I hear the question, How is all this to be tested? Nodoubt it is a pretty and ingenious way of looking at the structure ofany animal; but is it anything more? Does Nature acknowledge, in anydeeper way, this unity of plan we seem to trace?

The objection suggested by these questions is a very valid and importantone, and morphology was in an unsound state so long as it rested uponthe mere perception of the analogies which obtain between fully formedparts. The unchecked ingenuity of speculative anatomists proved itselffully competent to spin any number of contradictory hypotheses out ofthe same facts, and endless morphological dreams threatened to supplantscientific theory. 

Happily, however, there is a criterion of morphological truth, and asure test of all homologies. Our lobster has not always been what we seeit; it was once an egg, a semifluid mass of yolk, not so big as a pin'shead, contained in a transparent membrane, and exhibiting not the leasttrace of any one of those organs, whose multiplicity and complexity, inthe adult, are so surprising. After a time a delicate patch of cellularmembrane appeared upon one face of this yolk, and that patch was thefoundation of the whole creature, the clay out of which it wouldbe moulded. Gradually investing the yolk, it became subdivided bytransverse constrictions into segments, the forerunners of the rings ofthe body. Upon the ventral surface of each of the rings thus sketchedout, a pair of bud-like prominences made their appearance--the rudimentsof the appendages of the ring. At first, all the appendages were alike, but, as they grew, most of them became distinguished into a stem and twoterminal divisions, to which in the middle part of the body, was addeda third outer division; and it was only at a later period, that by themodification, or absorption, of certain of these primitive constituents, the limbs acquired their perfect form. 

Thus the study of development proves that the doctrine of unity of planis not merely a fancy, that it is not merely one way of looking at thematter, but that it is the expression of deep-seated natural facts. Thelegs and jaws of the lobster may not merely be regarded as modificationsof a common type, --in fact and in nature they are so, --the leg and thejaw of the young animal being, at first, indistinguishable. 

These are wonderful truths, the more so because the zoologist findsthem to be of universal application. The investigation of a polype, of asnail, of a fish, of a horse, or of a man, would have led us, thoughby a less easy path, perhaps, to exactly the same point. Unity of planeverywhere lies hidden under the mask of diversity of structure--thecomplex is everywhere evolved out of the simple. Every animal has atfirst the form of an egg, and every animal and every organic part, inreaching its adult state, passes through conditions common to otheranimals and other adult parts; and this leads me to another point. Ihave hitherto spoken as if the lobster were alone in the world, but, asI need hardly remind you, there are myriads of other animal organisms. Of these, some, such as men, horses, birds, fishes, snails, slugs, oysters, corals, and sponges, are not in the least like the lobster. Butother animals, though they may differ a good deal from the lobster, areyet either very like it, or are like something that is like it. Thecray fish, the rock lobster, and the prawn, and the shrimp, for example, however different, are yet so like lobsters, that a child would groupthem as of the lobster kind, in contradistinction to snails andslugs; and these last again would form a kind by themselves, incontradistinction to cows, horses, and sheep, the cattle kind. 

But this spontaneous grouping into "kinds" is the first essay of thehuman mind at classification, or the calling by a common name of thosethings that are alike, and the arranging them in such a manner as bestto suggest the sum of their likenesses and unlikenesses to other things. 

Those kinds which include no other subdivisions than the sexes, orvarious breeds, are called, in technical language, species. The Englishlobster is a species, our cray fish is another, our prawn is another. In other countries, however, there are lobsters, cray fish, and prawns, very like ours, and yet presenting sufficient differences to deservedistinction. Naturalists, therefore, express this resemblance and thisdiversity by grouping them as distinct species of the same "genus. " Butthe lobster and the cray fish, though belonging to distinct genera, havemany features in common, and hence are grouped together in an assemblagewhich is called a family. More distant resemblances connect the lobsterwith the prawn and the crab, which are expressed by putting all theseinto the same order. Again, more remote, but still very definite, resemblances unite the lobster with the woodlouse, the king crab, thewater flea, and the barnacle, and separate them from all other animals;whence they collectively constitute the larger group, or class, 'Crustacea'. But the 'Crustacea' exhibit many peculiar features incommon with insects, spiders, and centipedes, so that these are groupedinto the still larger assemblage or "province" 'Articulata'; and, finally, the relations which these have to worms and other loweranimals, are expressed by combining the whole vast aggregate into thesub-kingdom of 'Annulosa'. 

If I had worked my way from a sponge instead of a lobster, I should havefound it associated, by like ties, with a great number of other animalsinto the sub-kingdom 'Protozoa'; if I had selected a fresh-waterpolype or a coral, the members of what naturalists term the sub-kingdom'Coelenterata', would have grouped themselves around my type; had asnail been chosen, the inhabitants of all univalve and bivalve, land andwater, shells, the lamp shells, the squids, and the sea-mat would havegradually linked themselves on to it as members of the same sub-kingdomof 'Mollusca'; and finally, starting from man, I should have beencompelled to admit first, the ape, the rat, the horse, the dog, into thesame class; and then the bird, the crocodile, the turtle, the frog, andthe fish, into the same sub-kingdom of 'Vertebrata'. 

And if I had followed out all these various lines of classificationfully, I should discover in the end that there was no animal, eitherrecent or fossil, which did not at once fall into one or other of thesesub-kingdoms. In other words, every animal is organized upon oneor other of the five, or more, plans, whose existence renders ourclassification possible. And so definitely and precisely marked is thestructure of each animal, that, in the present state of our knowledge, there is not the least evidence to prove that a form, in the slightestdegree transitional between any of the two groups 'Vertebrata', 'Annulosa', 'Mollusca', and 'Coelenterata', either exists, or hasexisted, during that period of the earth's history which is recorded bythe geologist. Nevertheless, you must not for a moment suppose, because no such transitional forms are known, that the members of thesub-kingdoms are disconnected from, or independent of, one another. Onthe contrary, in their earliest condition they are all alike, and theprimordial germs of a man, a dog, a bird, a fish, a beetle, a snail, anda polype are, in no essential structural respects, distinguishable. 

In this broad sense, it may with truth be said, that all living animals, and all those dead creations which geology reveals, are bound togetherby an all-pervading unity of organization, of the same character, thoughnot equal in degree, to that which enables us to discern one and thesame plan amidst the twenty different segments of a lobster's body. Truly it has been said, that to a clear eye the smallest fact is awindow through which the Infinite may be seen. 

Turning from these purely morphological considerations, let us nowexamine into the manner in which the attentive study of the lobsterimpels us into other lines of research. 

Lobsters are found in all the European seas; but on the opposite shoresof the Atlantic and in the seas of the southern hemisphere they do notexist. They are, however, represented in these regions by very closelyallied, but distinct forms--the 'Homarus Americanus' and the 'HomarusCapensis': so that we may say that the European has one species of'Homarus'; the American, another; the African, another; and thus theremarkable facts of geographical distribution begin to dawn upon us. 

Again, if we examine the contents of the earth's crust, we shall findin the latter of those deposits, which have served as the great buryinggrounds of past ages, numberless lobster-like animals, but none sosimilar to our living lobster as to make zoologists sure that theybelonged even to the same genus. If we go still further back in time, we discover, in the oldest rocks of all, the remains of animals, constructed on the same general plan as the lobster, and belongingto the same great group of 'Crustacea'; but for the most part totallydifferent from the lobster, and indeed from any other living form ofcrustacean; and thus we gain a notion of that successive change of theanimal population of the globe, in past ages, which is the most strikingfact revealed by geology. 

Consider, now, where our inquiries have led us. We studied our typemorphologically, when we determined its anatomy and its development, andwhen comparing it, in these respects, with other animals, we made outits place in a system of classification. If we were to examine everyanimal in a similar manner, we should establish a complete body ofzoological morphology. 

Again, we investigated the distribution of our type in space and intime, and, if the like had been done with every animal, the sciencesof geographical and geological distribution would have attained theirlimit. 

But you will observe one remarkable circumstance, that, up to thispoint, the question of the life of these organisms has not come underconsideration. Morphology and distribution might be studied almostas well, if animals and plants were a peculiar kind of crystals, andpossessed none of those functions which distinguish living beings soremarkably. But the facts of morphology and distribution have to beaccounted for, and the science, whose aim it is to account for them, isPhysiology. 

Let us return to our lobster once more. If we watched the creature inits native element, we should see it climbing actively the submergedrocks, among which it delights to live, by means of its strong legs; orswimming by powerful strokes of its great tail, the appendages of whosesixth joint are spread out into a broad fan-like propeller: seizeit, and it will show you that its great claws are no mean weaponsof offence; suspend a piece of carrion among its haunts, and it willgreedily devour it, tearing and crushing the flesh by means of itsmultitudinous jaws. 

Suppose that we had known nothing of the lobster but as an inert mass, an organic crystal, if I may use the phrase, and that we could suddenlysee it exerting all these powers, what wonderful new ideas and newquestions would arise in our minds! The great new question would be, "How does all this take place?" the chief new idea would be, the ideaof adaptation to purpose, --the notion, that the constituents of animalbodies are not mere unconnected parts, but organs working together toan end. Let us consider the tail of the lobster again from this point ofview. Morphology has taught us that it is a series of segments composedof homologous parts, which undergo various modifications--beneath andthrough which a common plan of formation is discernible. But if I lookat the same part physiologically, I see that it is a most beautifullyconstructed organ of locomotion, by means of which the animal canswiftly propel itself either backwards or forwards. 

But how is this remarkable propulsive machine made to perform itsfunctions? If I were suddenly to kill one of these animals and to takeout all the soft parts, I should find the shell to be perfectlyinert, to have no more power of moving itself than is possessed bythe machinery of a mill when disconnected from its steam-engine orwater-wheel. But if I were to open it, and take out the viscera only, leaving the white flesh, I should perceive that the lobster could bendand extend its tail as well as before. If I were to cut off the tail, Ishould cease to find any spontaneous motion in it; but on pinching anyportion of the flesh, I should observe that it underwent a verycurious change--each fibre becoming shorter and thicker. By this act ofcontraction, as it is termed, the parts to which the ends of thefibre are attached are, of course, approximated; and according to therelations of their points of attachment to the centres of motions of thedifferent rings, the bending or the extension of the tail results. Closeobservation of the newly-opened lobster would soon show that all itsmovements are due to the same cause--the shortening and thickening ofthese fleshy fibres, which are technically called muscles. 

Here, then, is a capital fact. The movements of the lobster are due tomuscular contractility. But why does a muscle contract at one time andnot at another? Why does one whole group of muscles contract when thelobster wishes to extend his tail, and another group when he desires tobend it? What is it originates, directs, and controls the motive power?

Experiment, the great instrument for the ascertainment of truth inphysical science, answers this question for us. In the head of thelobster there lies a small mass of that peculiar tissue which is knownas nervous substance. Cords of similar matter connect this brain ofthe lobster, directly or indirectly, with the muscles. Now, if thesecommunicating cords are cut, the brain remaining entire, the power ofexerting what we call voluntary motion in the parts below the sectionis destroyed; and on the other hand, if, the cords remaining entire, thebrain mass be destroyed, the same voluntary mobility is equally lost. Whence the inevitable conclusion is, that the power of originating thesemotions resides in the brain, and is propagated along the nervous cords. 

In the higher animals the phenomena which attend this transmission havebeen investigated, and the exertion of the peculiar energy which residesin the nerves has been found to be accompanied by a disturbance of theelectrical state of their molecules. 

If we could exactly estimate the signification of this disturbance;if we could obtain the value of a given exertion of nerve force bydetermining the quantity of electricity, or of heat, of which it isthe equivalent; if we could ascertain upon what arrangement, or othercondition of the molecules of matter, the manifestation of the nervousand muscular energies depends (and doubtless science will some day orother ascertain these points), physiologists would have attained theirultimate goal in this direction; they would have determined the relationof the motive force of animals to the other forms of force found innature; and if the same process had been successfully performed forall the operations which are carried on in, and by, the animalframe, physiology would be perfect, and the facts of morphology anddistribution would be deducible from the laws which physiologistshad established, combined with those determining the condition of thesurrounding universe. 

There is not a fragment of the organism of this humble animal whosestudy would not lead us into regions of thought as large as those whichI have briefly opened up to you; but what I have been saying, I trust, has not only enabled you to form a conception of the scope and purportof zoology, but has given you an imperfect example of the manner inwhich, in my opinion, that science, or indeed any physical science, may be best taught. The great matter is, to make teaching real andpractical, by fixing the attention of the student on particular facts;but at the same time it should be rendered broad and comprehensive, byconstant reference to the generalizations of which all particular factsare illustrations. The lobster has served as a type of the whole animalkingdom, and its anatomy and physiology have illustrated for us someof the greatest truths of biology. The student who has once seen forhimself the facts which I have described, has had their relationsexplained to him, and has clearly comprehended them, has, so far, aknowledge of zoology, which is real and genuine, however limited it maybe, and which is worth more than all the mere reading knowledge of thescience he could ever acquire. His zoological information is, so far, knowledge and not mere hear-say. 

And if it were my business to fit you for the certificate in zoologicalscience granted by this department, I should pursue a course preciselysimilar in principle to that which I have taken to-night. I shouldselect a fresh-water sponge, a fresh-water polype or a 'Cyanaea', afresh-water mussel, a lobster, a fowl, as types of the five primarydivisions of the animal kingdom. I should explain their structure veryfully, and show how each illustrated the great principles of zoology. Having gone very carefully and fully over this ground, I should feelthat you had a safe foundation, and I should then take you in the sameway, but less minutely, over similarly selected illustrative types ofthe classes; and then I should direct your attention to the specialforms enumerated under the head of types, in this syllabus, and to theother facts there mentioned. 

That would, speaking generally, be my plan. But I have undertaken toexplain to you the best mode of acquiring and communicating a knowledgeof zoology, and you may therefore fairly ask me for a more detailed andprecise account of the manner in which I should propose to furnish youwith the information I refer to. 

My own impression is, that the best model for all kinds of training inphysical science is that afforded by the method of teaching anatomy, in use in the medical schools. This method consists of threeelements--lectures, demonstrations, and examinations. 

The object of lectures is, in the first place, to awaken the attentionand excite the enthusiasm of the student; and this, I am sure, maybe effected to a far greater extent by the oral discourse and bythe personal influence of a respected teacher than in any other way. Secondly, lectures have the double use of guiding the student to thesalient points of a subject, and at the same time forcing him to attendto the whole of it, and not merely to that part which takes his fancy. And lastly, lectures afford the student the opportunity of seekingexplanations of those difficulties which will, and indeed ought to, arise in the course of his studies. 

But for a student to derive the utmost possible value from lectures, several precautions are needful. 

I have a strong impression that the better a discourse is, as anoration, the worse it is as a lecture. The flow of the discourse carriesyou on without proper attention to its sense; you drop a word or aphrase, you lose the exact meaning for a moment, and while you strive torecover yourself, the speaker has passed on to something else. 

The practice I have adopted of late years, in lecturing to students, is to condense the substance of the hour's discourse into a few drypropositions, which are read slowly and taken down from dictation;the reading of each being followed by a free commentary expandingand illustrating the proposition, explaining terms, and removing anydifficulties that may be attackable in that way, by diagrams maderoughly, and seen to grow under the lecturer's hand. In this manner you, at any rate, insure the co-operation of the student to a certain extent. He cannot leave the lecture-room entirely empty if the taking of notesis enforced; and a student must be preternaturally dull and mechanical, if he can take notes and hear them properly explained, and yet learnnothing. 

What books shall I read? is a question constantly put by the student tothe teacher. My reply usually is, "None: write your notes out carefullyand fully; strive to understand them thoroughly; come to me for theexplanation of anything you cannot understand; and I would rather youdid not distract your mind by reading. " A properly composed courseof lectures ought to contain fully as much matter as a student canassimilate in the time occupied by its delivery; and the teacher shouldalways recollect that his business is to feed, and not to cram theintellect. Indeed, I believe that a student who gains from a courseof lectures the simple habit of concentrating his attention upon adefinitely limited series of facts, until they are thoroughly mastered, has made a step of immeasurable importance. 

But, however good lectures may be, and however extensive the course ofreading by which they are followed up, they are but accessories to thegreat instrument of scientific teaching--demonstration. If I insistunweariedly, nay fanatically, upon the importance of physical science asan educational agent, it is because the study of any branch of science, if properly conducted, appears to me to fill up a void left by all othermeans of education. I have the greatest respect and love for literature;nothing would grieve me more than to see literary training other thana very prominent branch of education: indeed, I wish that real literarydiscipline were far more attended to than it is; but I cannot shut myeyes to the fact, that there is a vast difference between men whohave had a purely literary, and those who have had a sound scientific, training. 

Seeking for the cause of this difference, I imagine I can find it in thefact that, in the world of letters, learning and knowledge are one, andbooks are the source of both; whereas in science, as in life, learningand knowledge are distinct, and the study of things, and not of books, is the source of the latter. 

All that literature has to bestow may be obtained by reading and bypractical exercise in writing and in speaking; but I do not exaggeratewhen I say, that none of the best gifts of science are to be won bythese means. On the contrary, the great benefit which a scientificeducation bestows, whether as training or as knowledge, is dependentupon the extent to which the mind of the student is brought intoimmediate contact with facts--upon the degree to which he learns thehabit of appealing directly to Nature, and of acquiring through hissenses concrete images of those properties of things, which are, andalways will be, but approximatively expressed in human language. Ourway of looking at Nature, and of speaking about her, varies from yearto year; but a fact once seen, a relation of cause and effect, oncedemonstratively apprehended, are possessions which neither change norpass away, but, on the contrary, form fixed centres, about which othertruths aggregate by natural affinity. 

Therefore, the great business of the scientific teacher is, to imprintthe fundamental, irrefragable facts of his science, not only by wordsupon the mind, but by sensible impressions upon the eye, and ear, andtouch of the student, in so complete a manner, that every term used, orlaw enunciated, should afterwards call up vivid images of the particularstructural, or other, facts which furnished the demonstration of thelaw, or the illustration of the term. 

Now this important operation can only be achieved by constantdemonstration, which may take place to a certain imperfect extent duringa lecture, but which ought also to be carried on independently, andwhich should be addressed to each individual student, the teacherendeavouring, not so much to show a thing to the learner, as to make himsee it for himself. 

I am well aware that there are great practical difficulties in the wayof effectual zoological demonstrations. The dissection of animals is notaltogether pleasant, and requires much time; nor is it easy to secure anadequate supply of the needful specimens. The botanist has here a greatadvantage; his specimens are easily obtained, are clean and wholesome, and can be dissected in a private house as well as anywhere else; andhence, I believe, the fact, that botany is so much more readily andbetter taught than its sister science. But, be it difficult or be iteasy, if zoological science is to be properly studied, demonstration, and, consequently, dissection, must be had. Without it, no man can havea really sound knowledge of animal organization. 

A good deal may be done, however, without actual dissection on thestudent's part, by demonstration upon specimens and preparations; andin all probability it would not be very difficult, were the demandsufficient, to organize collections of such objects, sufficient for allthe purposes of elementary teaching, at a comparatively cheap rate. Evenwithout these, much might be effected, if the zoological collections, which are open to the public, were arranged according to what has beentermed the "typical principle"; that is to say, if the specimens exposedto public view were so selected that the public could learn somethingfrom them, instead of being, as at present, merely confused by theirmultiplicity. For example, the grand ornithological gallery at theBritish Museum contains between two and three thousand species of birds, and sometimes five or six specimens of a species. They are very prettyto look at, and some of the cases are, indeed, splendid; but I willundertake to say, that no man but a professed ornithologist has evergathered much information from the collection. Certainly, no one of thetens of thousands of the general public who have walked through thatgallery ever knew more about the essential peculiarities of birds whenhe left the gallery than when he entered it. But if, somewhere in thatvast hall, there were a few preparations, exemplifying the leadingstructural peculiarities and the mode of development of a common fowl;if the types of the genera, the leading modifications in the skeleton, in the plumage at various ages, in the mode of nidification, and thelike, among birds, were displayed; and if the other specimens were putaway in a place where the men of science, to whom they are alone useful, could have free access to them, I can conceive that this collectionmight become a great instrument of scientific education. 

The last implement of the teacher to which I have adverted isexamination--a means of education now so thoroughly understood thatI need hardly enlarge upon it. I hold that both written and oralexaminations are indispensable, and, by requiring the description ofspecimens, they may be made to supplement demonstration. 

Such is the fullest reply the time at my disposal will allow me to giveto the question--how may a knowledge of zoology be best acquired andcommunicated?

But there is a previous question which may be moved, and which, infact, I know many are inclined to move. It is the question, why shouldtraining masters be encouraged to acquire a knowledge of this, orany other branch of physical science? What is the use, it is said, ofattempting to make physical science a branch of primary education? Is itnot probable that teachers, in pursuing such studies, will be led astrayfrom the acquirement of more important but less attractive knowledge?And, even if they can learn something of science without prejudice totheir usefulness, what is the good of their attempting to instil thatknowledge into boys whose real business is the acquisition of reading, writing, and arithmetic?

These questions are, and will be, very commonly asked, for they arisefrom that profound ignorance of the value and true position of physicalscience, which infests the minds of the most highly educated andintelligent classes of the community. But if I did not feel well assuredthat they are capable of being easily and satisfactorily answered; thatthey have been answered over and over again; and that the time will comewhen men of liberal education will blush to raise such questions, --Ishould be ashamed of my position here to-night. Without doubt, itis your great and very important function to carry out elementaryeducation; without question, anything that should interfere with thefaithful fulfilment of that duty on your part would be a great evil; andif I thought that your acquirement of the elements of physical science, and your communication of those elements to your pupils, involved anysort of interference with your proper duties, I should be the firstperson to protest against your being encouraged to do anything of thekind. 

But is it true that the acquisition of such a knowledge of science asis proposed, and the communication of that knowledge, are calculated toweaken your usefulness? Or may I not rather ask, is it possible for youto discharge your functions properly without these aids?

What is the purpose of primary intellectual education? I apprehendthat its first object is to train the young in the use of those toolswherewith men extract knowledge from the ever-shifting succession ofphenomena which pass before their eyes; and that its second object is toinform them of the fundamental laws which have been found by experienceto govern the course of things, so that they may not be turned outinto the world naked, defenceless, and a prey to the events they mightcontrol. 

A boy is taught to read his own and other languages, in order that hemay have access to infinitely wider stores of knowledge than could everbe opened to him by oral intercourse with his fellow men; he learns towrite, that his means of communication with the rest of mankind may beindefinitely enlarged, and that he may record and store up the knowledgehe acquires. He is taught elementary mathematics, that he may understandall those relations of number and form, upon which the transactions ofmen, associated in complicated societies, are built, and that he mayhave some practice in deductive reasoning. 

All these operations of reading, writing, and ciphering, areintellectual tools, whose use should, before all things, be learned, andlearned thoroughly; so that the youth may be enabled to make his lifethat which it ought to be, a continual progress in learning and inwisdom. 

But, in addition, primary education endeavours to fit a boy out with acertain equipment of positive knowledge. He is taught the great lawsof morality; the religion of his sect; so much history and geography aswill tell him where the great countries of the world are, what they are, and how they have become what they are. 

Without doubt all these are most fitting and excellent things to teacha boy; I should be very sorry to omit any of them from any scheme ofprimary intellectual education. The system is excellent, so far as itgoes. 

But if I regard it closely, a curious reflection arises. I suppose that, fifteen hundred years ago, the child of any well-to-do Roman citizenwas taught just these same things; reading and writing in his own, and, perhaps, the Greek tongue; the elements of mathematics; andthe religion, morality, history, and geography current in his time. Furthermore, I do not think I err in affirming, that, if sucha Christian Roman boy, who had finished his education, could betransplanted into one of our public schools, and pass through its courseof instruction, he would not meet with a single unfamiliar line ofthought; amidst all the new facts he would have to learn, not one wouldsuggest a different mode of regarding the universe from that current inhis own time. 

And yet surely there is some great difference between the civilizationof the fourth century and that of the nineteenth, and still more betweenthe intellectual habits and tone of thought of that day and this?

And what has made this difference? I answer fearlessly--The prodigiousdevelopment of physical science within the last two centuries. 

Modern civilization rests upon physical science; take away her gifts toour own country, and our position among the leading nations of theworld is gone to-morrow; for it is physical science only, that makesintelligence and moral energy stronger than brute force. 

The whole of modern thought is steeped in science; it has made its wayinto the works of our best poets, and even the mere man of letters, whoaffects to ignore and despise science, is unconsciously impregnated withher spirit, and indebted for his best products to her methods. I believethat the greatest intellectual revolution mankind has yet seen is nowslowly taking place by her agency. She is teaching the world thatthe ultimate court of appeal is observation and experiment, and notauthority; she is teaching it to estimate the value of evidence; she iscreating a firm and living faith in the existence of immutable moral andphysical laws, perfect obedience to which is the highest possible aim ofan intelligent being. 

But of all this your old stereotyped system of education takes no note. Physical science, its methods, its problems, and its difficulties, willmeet the poorest boy at every turn, and yet we educate him in such amanner that he shall enter the world as ignorant of the existence of themethods and facts of science as the day he was born. The modern worldis full of artillery; and we turn out our children to do battle in it, equipped with the shield and sword of an ancient gladiator. 

Posterity will cry shame on us if we do not remedy this deplorable stateof things. Nay, if we live twenty years longer, our own consciences willcry shame on us. 

It is my firm conviction that the only way to remedy it is, to make theelements of physical science an integral part of primary education. Ihave endeavoured to show you how that may be done for that branch ofscience which it is my business to pursue; and I can but add, that Ishould look upon the day when every schoolmaster throughout this landwas a centre of genuine, however rudimentary, scientific knowledge, asan epoch in the history of the country. 

But let me entreat you to remember my last words. Addressing myself toyou, as teachers, I would say, mere book learning in physical science isa sham and a delusion--what you teach, unless you wish to be impostors, that you must first know; and real knowledge in science means personalacquaintance with the facts, be they few or many. [2]

[Footnote 1: A Lecture delivered at the South Kensington Museum in1861. ]

[Footnote 2: It has been suggested to me that these words may betaken to imply a discouragement on my part of any sort of scientificinstruction which does not give an acquaintance with the facts at firsthand. But this is not my meaning. The ideal of scientific teaching is, no doubt, a system by which the scholar sees every fact for himself, andthe teacher supplies only the explanations. Circumstances, however, donot often allow of the attainment of that ideal, and we must put upwith the next best system--one in which the scholar takes a good deal ontrust from a teacher, who, knowing the facts by his own knowledge, candescribe them with so much vividness as to enable his audience to formcompetent ideas concerning them. The system which I repudiate is thatwhich allows teachers who have not come into direct contact with theleading facts of a science to pass their second-hand information on. The scientific virus, like vaccine lymph, if passed through too longa succession of organisms, will lose all its effect in protecting theyoung against the intellectual epidemics to which they are exposed. ]