WILLIAM HARVEY AND THE DISCOVERY OF THE CIRCULATION OF THE BLOOD

By Thomas H. Huxley

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I DESIRE this evening to give you some account of the life and laboursof a very noble Englishman--William Harvey. 

William Harvey was born in the year 1578, and as he lived until the year1657, he very nearly attained the age of 80. He was the son of a smalllandowner in Kent, who was sufficiently wealthy to send this, his eldestson, to the University of Cambridge; while he embarked the others inmercantile pursuits, in which they all, as time passed on, attainedriches. 

William Harvey, after pursuing his education at Cambridge, and takinghis degree there, thought it was advisable--and justly thought so, inthe then state of University education--to proceed to Italy, whichat that time was one of the great centres of intellectual activity inEurope, as all friends of freedom hope it will become again, sooner orlater. In those days the University of Padua had a great renown;and Harvey went there and studied under a man who was then veryfamous--Fabricius of Aquapendente. On his return to England, Harveybecame a member of the College of Physicians in London, and entered intopractice; and, I suppose, as an indispensable step thereto, proceededto marry. He very soon became one of the most eminent members of theprofession in London; and, about the year 1616, he was elected by theCollege of Physicians their Professor of Anatomy. It was while Harveyheld this office that he made public that great discovery of thecirculation of the blood and the movements of the heart, the nature ofwhich I shall endeavour by-and-by to explain to you at length. Shortlyafterwards, Charles the First having succeeded to the throne in 1625, Harvey became one of the king's physicians; and it is much to the creditof the unfortunate monarch--who, whatever his faults may have been, was one of the few English monarchs who have shown a taste for art andscience--that Harvey became his attached and devoted friend as wellas servant; and that the king, on the other hand, did all he could toadvance Harvey's investigations. But, as you know, evil times came on;and Harvey, after the fortunes of his royal master were broken, being then a man of somewhat advanced years--over 60 years of age, infact--retired to the society of his brothers in and near London, andamong them pursued his studies until the day of his death. Harvey'scareer is a life which offers no salient points of interest to thebiographer. It was a life devoted to study and investigation; and itwas a life the devotion of which was amply rewarded, as I shall haveoccasion to point out to you, by its results. 

Harvey, by the diversity, the variety, and the thoroughness of hisinvestigations, was enabled to give an entirely new direction to atleast two branches--and two of the most important branches--of whatnow-a-days we call Biological Science. On the one hand, he foundedall our modern physiology by the discovery of the exact nature of themotions of the heart, and of the course in which the blood is propelledthrough the body; and, on the other, he laid the foundation of thatstudy of development which has been so much advanced of late years, andwhich constitutes one of the great pillars of the doctrine of evolution. This doctrine, I need hardly tell you, is now tending to revolutioniseour conceptions of the origin of living things, exactly in the sameway as Harvey's discovery of the circulation in the seventeeth centuryrevolutionised the conceptions which men had previously entertained withregard to physiological processes. 

It would, I regret, be quite impossible for me to attempt, in the courseof the time I can presume to hold you here, to unfold the history ofmore than one of these great investigations of Harvey. I call them"great investigations, " as distinguished from "large publications. " Ihave in my hand a little book, which those of you who are at a greatdistance may have some difficulty in seeing, and which I value verymuch. It is, I am afraid, sadly thumbed and scratched with annotationsby a very humble successor and follower of Harvey. This little book isthe edition of 1651 of the 'Exercitationes de Generatione'; and if youwere to add another little book, printed in the same small type, andabout one-seventh of the thickness, you would have the sum total of theprinted matter which Harvey contributed to our literature. And yetin that sum total was contained, I may say, the materials of tworevolutions in as many of the main branches of biological science. IfHarvey's published labours can be condensed into so small a compass, youmust recollect that it is not because he did not do a great deal more. We know very well that he did accumulate a very considerable number ofobservations on the most varied topics of medicine, surgery, and naturalhistory. But, as I mentioned to you just now, Harvey, for a time, tookthe royal side in the domestic quarrel of the Great Rebellion, as itis called; and the Parliament, not unnaturally resenting that action ofhis, sent soldiers to seize his papers. And while I imagine they foundnothing treasonable among those papers, yet, in the process of rummagingthrough them, they destroyed all the materials which Harvey had spent alaborious life in accumulating; and hence it is that the man's work andlabours are represented by so little in apparent bulk. 

What I chiefly propose to do to-night is to lay before you an account ofthe nature of the discovery which Harvey made, and which is termed theDiscovery of the Circulation of the Blood. And I desire also, withsome particularity, to draw your attention to the methods by which thatdiscovery was achieved; for, in both these respects, I think, there willbe much matter for profitable reflection. 

Let me point out to you, in the first place, with respect to thisimportant matter of the movements of the heart and the course of theblood in the body, that there is a certain amount of knowledgewhich must have been obtained without men taking the trouble to seekit--knowledge which must have been taken in, in the course of time, by everybody who followed the trade of a butcher, and still more so bythose people who, in ancient times, professed to divine the course offuture events from the entrails of animals. It is quite obvious toall, from ordinary accidents, that the bodies of all the higher animalscontain a hot red fluid--the blood. Everybody can see upon the surfaceof some part of the skin, underneath that skin, pulsating tubes, whichwe know as the arteries. Everybody can see under the surface of the skinmore delicate and softer looking tubes, which do not pulsate, which areof a bluish colour, and are termed the veins. And every person who hasseen a recently killed animal opened knows that these two kinds of tubesto which I have just referred, are connected with an apparatus whichis placed in the chest, which apparatus, in recently killed animals, is still pulsating. And you know that in yourselves you can feel thepulsation of this organ, the heart, between the fifth and sixth ribs. Itake it that this much of anatomy and physiology has been known from theoldest times, not only as a matter of curiosity, but because one of thegreat objects of men, from their earliest recorded existence, has beento kill one another, and it was a matter of considerable importance toknow which was the best place for hitting an enemy. I can refer you tovery ancient records for most precise and clear information that one ofthe best places is to smite him between the fifth and sixth ribs. Nowthat is a very good piece of regional anatomy, for that is the placewhere the heart strikes in its pulsations, and the use of smiting thereis that you go straight to the heart. Well, all that must have beenknown from time immemorial--at least for 4, 000 or 5, 000 years before thecommencement of our era--because we know that for as great a period asthat the Egyptians, at any rate, whatever may have been the case withother people, were in the enjoyment of a highly developed civilisation. But of what knowledge they may have possessed beyond this we knownothing; and in tracing back the springs of the origin of everythingthat we call "modern science" (which is not merely knowing, but knowingsystematically, and with the intention and endeavour to find outthe causal connection of things)--I say that when we trace back thedifferent lines of all the modern sciences we come at length to oneepoch and to one country--the epoch being about the fourth and fifthcenturies before Christ, and the country being ancient Greece. It isthere that we find the commencement and the root of every branch ofphysical science and of scientific method. If we go back to that timewe have in the works attributed to Aristotle, who flourished between 300and 400 years before Christ, a sort of encyclopaedia of the scientificknowledge of that day--and a very marvellous collection of, in manyrespects, accurate and precise knowledge it is. But, so far as regardsthis particular topic, Aristotle, it must be confessed, has not got veryfar beyond common knowledge. He knows a little about the structure ofthe heart. I do not think that his knowledge is so inaccurate as manypeople fancy, but it does not amount to much. A very few years after histime, however, there was a Greek philosopher, Erasistratus, who livedabout three hundred years before Christ, and who must have pursuedanatomy with much care, for he made the important discovery that thereare membranous flaps, which are now called "valves, " at the originsof the great vessels; and that there are certain other valves in theinterior of the heart itself. 

Fig. 1. --The apparatus of the circulation, as at present known. Thecapillary vessels, which connect the arteries and veins, are omitted, onaccount of their small size. The shading of the "venous system" is givento all the vessels which contain venous blood; that of the "arterialsystem" to all the vessels which contain arterial blood. 

I have here (Fig. 1) a purposely rough, but, so far as it goes, accurate, diagram of the structure of the heart and the course of theblood. The heart is supposed to be divided into two portions. It wouldbe possible, by very careful dissection, to split the heart down themiddle of a partition, or so-called 'septum', which exists in it, and todivide it into the two portions which you see here represented; in whichcase we should have a left heart and a right heart, quite distinct fromone another. You will observe that there is a portion of each heartwhich is what is called the ventricle. Now the ancients applied the term'heart' simply and solely to the ventricles. They did not count the restof the heart--what we now speak of as the 'auricles'--as any part of theheart at all; but when they spoke of the heart they meant the left andthe right ventricles; and they described those great vessels, which wenow call the 'pulmonary veins' and the 'vena cava', as opening directlyinto the heart itself. 

What Erasistratus made out was that, at the roots of the aorta andthe pulmonary artery (Fig. 1) there were valves, which opened in thedirection indicated by the arrows; and, on the other hand, that at thejunction of what he called the veins with the heart there were othervalves, which also opened again in the direction indicated by thearrows. This was a very capital discovery, because it proved that ifthe heart was full of fluid, and if there were any means of causing thatfluid in the ventricles to move, then the fluid could move only inone direction; for you will observe that, as soon as the fluid iscompressed, the two valves between the ventricles and the veins will beshut, and the fluid will be obliged to move into the arteries; and, if it tries to get back from them into the heart, it is prevented fromdoing so by the valves at the origin of the arteries, which we nowcall the semilunar valves (half-moon shaped valves); so that it isimpossible, if the fluid move at all, that it should move in any otherway than from the great veins into the arteries. Now that was a veryremarkable and striking discovery. 

But it is not given to any man to be altogether right (that is areflection which it is very desirable for every man who has had the goodluck to be nearly right once, always to bear in mind); and Erasistratus, while he made this capital and important discovery, made a very capitaland important error in another direction, although it was a very naturalerror. If, in any animal which is recently killed, you open one of thosepulsating trunks which I referred to a short time ago, you will find, asa general rule, that it either contains no blood at all or next to none;but that, on the contrary, it is full of air. Very naturally, therefore, Erasistratus came to the conclusion that this was the normal and naturalstate of the arteries, and that they contained air. We are apt to thinkthis a very gross blunder; but, to anybody who is acquainted withthe facts of the case, it is, at first sight, an exceedingly naturalconclusion. Not only so, but Erasistratus might have very justlyimagined that he had seen his way to the meaning of the connection ofthe left side of the heart with the lungs; for we find that what we nowcall the pulmonary vein is connected with the lungs, and branches out inthem (Fig. 1). Finding that the greater part of this system of vesselswas filled with air after death, this ancient thinker very shrewdlyconcluded that its real business was to receive air from the lungs, andto distribute that air all through the body, so as to get rid of thegrosser humours and purify the blood. That was a very natural and veryobvious suggestion, and a highly ingenious one, though it happened to bea great error. You will observe that the only way of correcting it wasto experiment upon living animals, for there is no other way in whichthis point could be settled. 

Fig. 2, --The Course of the Blood according to Galen (A. D. 170). 

And hence we are indebted, for the correction of the error ofErasistratus, to one of the greatest experimenters of ancient or moderntimes, Claudius Galenus, who lived in the second century after Christ. Isay it was to this man more than any one else, because he knew that theonly way of solving physiological problems was to examine into the factsin the living animal. And because Galen was a skilful anatomist, anda skilful experimenter, he was able to show in what particularsErasistratus had erred, and to build up a system of thought upon thissubject which was not improved upon for fully 1, 300 years. I haveendeavoured, in Fig. 2, to make clear to you exactly what it was hetried to establish. You will observe that this diagram is practicallythe same as that given in Fig. 1, only simplified. The same facts maybe looked upon by different people from different points of view. Galenlooked upon these facts from a very different point of view from thatwhich we ourselves occupy; but, so far as the facts are concerned, theywere the same for him as for us. Well then, the first thing that Galendid was to make out experimentally that, during life, the arteries arenot full of air, but that they are full of blood. And he describes agreat variety of experiments which he made upon living animals with theview of proving this point, which he did prove effectually and for alltime; and that you will observe was the only way of settling the matter. Furthermore, he demonstrated that the cavities of the left side of theheart--what we now call the left auricle and the left ventricle--are, like the arteries, full of blood during life, and that that blood was ofthe scarlet kind--arterialised, or as he called it "pneumatised, " blood. It was known before, that the pulmonary artery, the right ventricle, and the veins, contain the darker kind of blood, which was thence calledvenous. Having proved that the whole of the left side of the heart, during life, is full of scarlet arterial blood, Galen's next pointwas to inquire into the mode of communication between the arteriesand veins. It was known before his time that both arteries and veinsbranched out. Galen maintained, though he could not prove the fact, thatthe ultimate branches of the arteries and veins communicated togethersomehow or other, by what he called 'anastomoses', and that these'anastomoses' existed not only in the body in general but also in thelungs. In the next place, Galen maintained that all the veins ofthe body arise from the liver; that they draw the blood thence anddistribute it over the body. People laugh at that notion now-a-days; butif anybody will look at the facts he will see that it is a very probablesupposition. There is a great vein (hepatic vein--Fig. 1) which risesout of the liver, and that vein goes straight into the 'vena cava' (Fig. 1) which passes to the heart, being there joined by the other veinsof the body. The liver itself is fed by a very large vein (portalvein--Fig. 1), which comes from the alimentary canal. The way theancients looked at this matter was, that the food, after being receivedinto the alimentary canal, was then taken up by the branches of thisgreat vein, which are called the 'vena portae', just as the roots of aplant suck up nourishment from the soil in which it lives; that then itwas carried to the liver, there to be what was called "concocted, " whichwas their phrase for its conversion into substances more fitted fornutrition than previously existed in it. They then supposed that thenext thing to be done was to distribute this fluid through the body; andGalen like his predecessors, imagined that the "concocted" blood, havingentered the great 'vena cava', was distributed by its ramifications allover the body. So that, in his view (Fig. 2), the course of the bloodwas from the intestine to the liver, and from the liver into the great'vena cava', including what we now call the right auricle of the heart, whence it was distributed by the branches of the veins. But the whole ofthe blood was not thus disposed of. Part of the blood, it was supposed, went through what we now call the pulmonary arteries (Fig. 1), and, branching out there, gave exit to certain "fuliginous" products, andat the same time took in from the air a something which Galen calls the'pneuma'. He does not know anything about what we call oxygen; but itis astonishing how very easy it would be to turn his language into theequivalent of modern chemical theory. The old philosopher had so justa suspicion of the real state of affairs that you could make use of hislanguage in many cases, if you substituted the word "oxygen, " which wenow-a-days use, for the word 'pneuma'. Then he imagined that the blood, further concocted or altered by contact with the 'pneuma', passed toa certain extent to the left side of the heart. So that Galen believedthat there was such a thing as what is now called the pulmonarycirculation. He believed, as much as we do, that the blood passedthrough the right side of the heart, through the artery which goes tothe lungs, through the lungs themselves, and back by what we call thepulmonary veins to the left side of the heart. But he thought it wasonly a very small portion of the blood which passes to the right side ofthe heart in this way; the rest of the blood, he thought, passed throughthe partition which separates the two ventricles of the heart. Hedescribes a number of small pits, which really exist there, as holes, and he supposed that the greater part of the blood passed through theseholes from the right to the left ventricle (Fig 2). 

It is of great importance you should clearly understand these teachingsof Galen, because, as I said just now, they sum up all that anybody knewuntil the revival of learning; and they come to this--that the bloodhaving passed from the stomach and intestines through the liver, andhaving entered the great veins, was by them distributed to every part ofthe body; that part of the blood, thus distributed, entered the arterialsystem by the 'anastomoses', as Galen called them, in the lungs; thata very small portion of it entered the arteries by the 'anastomoses' inthe body generally; but that the greater part of it passed through theseptum of the heart, and so entered the left side and mingled with thepneumatised blood, which had been subjected to the air in the lungs, and was then distributed by the arteries, and eventually mixed with thecurrents of blood, coming the other way, through the veins. 

Yet one other point about the views of Galen. He thought that both thecontractions and dilatations of the heart--what we call the 'systole'or contraction of the heart, and the 'diastole' or dilatation--Galenthought that these were both active movements; that the heart activelydilated, so that it had a sort of sucking power upon the fluids whichhad access to it. And again, with respect to the movements of the pulse, which anybody can feel at the wrist and elsewhere, Galen was of opinionthat the walls of the arteries partook of that which he supposed to bethe nature of the walls of the heart, and that they had the power ofalternately actively contracting and actively dilating, so that he iscareful to say that the nature of the pulse is comparable, not to themovement of a bag, which we fill by blowing into it, and which we emptyby drawing the air out of it, but to the action of a bellows, which isactively dilated and actively compressed. 

Fig 3. --The course of the blood from the right to the left side of theheart (Realdus Columbus, 1559). 

After Galen's time came the collapse of the Roman Empire, the extinctionof physical knowledge, and the repression of every kind of scientificinquiry, by its powerful and consistent enemy, the Church; and thatstate of things lasted until the latter part of the Middle Ages saw therevival of learning. That revival of learning, so far as anatomyand physiology are concerned, is due to the renewed influence ofthe philosophers of ancient Greece, and indeed, of Galen. Arabiccommentators had translated Galen, and portions of his works had gotinto the language of the learned in the Middle Ages, in that way;but, by the study of the classical languages, the original text becameaccessible to the men who were then endeavouring to learn for themselvessomething about the facts of nature. It was a century or more beforethese men, finding themselves in the presence of a master--finding thatall their lives were occupied in attempting to ascertain for themselvesthat which was familiar to him--I say it took the best part of a hundredyears before they could fairly see that their business was not to followhim, but to follow his example--namely, to look into the facts of naturefor themselves, and to carry on, in his spirit, the work he had begun. That was first done by Vesalius, one of the greatest anatomists who everlived; but his work does not specially bear upon the question we arenow concerned with. So far as regards the motions of the heart and thecourse of the blood, the first man in the Middle Ages, and indeed theonly man who did anything which was of real importance, was one RealdusColumbus, who was professor at Padua in the year 1559, and published agreat anatomical treatise. What Realdus Columbus did was this; oncemore resorting to the method of Galen, turning to the living animal, experimenting, he came upon new facts, and one of these new facts wasthat there was not merely a subordinate communication between the bloodof the right side of the heart and that of the left side of the heart, through the lungs, but that there was a constant steady current ofblood, setting through the pulmonary artery on the right side, throughthe lungs, and back by the pulmonary veins to the left side of the heart(Fig. 3). Such was the capital discovery and demonstration of RealdusColumbus. He is the man who discovered what is loosely called the'pulmonary circulation'; and it really is quite absurd, in the face ofthe fact, that twenty years afterwards we find Ambrose Pare, the greatFrench surgeon, ascribing this discovery to him as a matter of commonnotoriety, to find that attempts are made to give the credit of it toother people. So far as I know, this discovery of the course of theblood through the lungs, which is called the pulmonary circulation, isthe one step in real advance that was made between the time of Galenand the time of Harvey. And I would beg you to note that the word"circulation" is improperly employed when it is applied to the course ofthe blood through the lungs. The blood from the right side of theheart, in getting to the left side of the heart, only performs ahalf-circle--it does not perform a whole circle--it does not returnto the place from whence it started; and hence the discovery of theso-called "pulmonary circulation" has nothing whatever to do with thatgreater discovery which I shall point out to you by-and-by was madeby Harvey, and which is alone really entitled to the name of thecirculation of the blood. 

If anybody wants to understand what Harvey's great desert really was, I would suggest to him that he devote himself to a course of reading, which I cannot promise shall be very entertaining, but which, in thisrespect at any rate, will be highly instructive--namely, the works ofthe anatomists of the latter part of the 16th century and the beginningof the 17th century. If anybody will take the trouble to do that whichI have thought it my business to do, he will find that the doctrinesrespecting the action of the heart and the motion of the blood whichwere taught in every university in Europe, whether in Padua or in Paris, were essentially those put forward by Galen, 'plus' the discovery of thepulmonary course of the blood which had been made by Realdus Columbus. In every chair of anatomy and physiology (which studies were not thenseparated) in Europe, it was taught that the blood brought to the liverby the portal vein, and carried out of the liver to the 'vena cava'by the hepatic vein, is distributed from the right side of the heart, through the other veins, to all parts of the body; that the blood of thearteries takes a like course from the heart towards the periphery; andthat it is there, by means of the 'anastomoses', more or less mixed upwith the venous blood. It so happens, by a curious chance, that up tothe year 1625 there was at Padua, which was Harvey's own university, avery distinguished professor, Spigelius, whose work is extant, and whoteaches exactly what I am now telling you. It is perfectly truethat, some time before, Harvey's master, Fabricius, had not onlyre-discovered, but had drawn much attention to certain pouch-likestructures, which are called the valves of the veins, found in themuscular parts of the body, all of which are directed towards the heart, and consequently impede the flow of the blood in the opposite direction. And you will find it stated by people who have not thought much aboutthe matter, that it was this discovery of the valves of the veins whichled Harvey to imagine the course of the circulation of the blood. Nowit did not lead Harvey to imagine anything of the kind. He had heardall about it from his master, Fabricius, who made a great point ofthese valves in the veins, and he had heard the theories which Fabriciusentertained upon the subject, whose impression as to the use of thevalves was simply this--that they tended to take off any excess ofpressure of the blood in passing from the heart to the extremities; forFabricius believed, with the rest of the world, that the blood in theveins flowed from the heart towards the extremities. This, under thecircumstances, was as good a theory as any other, because the action ofthe valves depends altogether upon the form and nature of the wallsof the structures in which they are attached; and without accurateexperiment, it was impossible to say whether the theory of Fabriciuswas right or wrong. But we not only have the evidence of the factsthemselves that these could tell Harvey nothing about the circulation, but we have his own distinct declaration as to the considerations whichled him to the true theory of the circulation of the blood, and amongstthese the valves of the veins are not mentioned. 

Fig. 4. --The circulation of the blood as demonstrated by Harvey (A. D. 1628). 

Now then we may come to Harvey himself. When you read Harvey's treatise, which is one of the most remarkable scientific monographs with which Iam acquainted--it occupies between 50 and 60 pages of a small quarto inLatin, and is as terse and concise as it possibly can be--when you cometo look at Harvey's work, you will find that he had long struggled withthe difficulties of the accepted doctrine of the circulation. He hadreceived from Fabricius, and from all the great authorities of the day, the current view of the circulation of the blood. But he was a manwith that rarest of all qualities--intellectual honesty; and by dint ofcultivating that great faculty, which is more moral than intellectual, it had become impossible for him to say he believed anything which hedid not clearly believe. This is a most uncomfortable peculiarity--forit gets you into all sorts of difficulties with all sorts ofpeople--but, for scientific purposes, it is absolutely invaluable. Harvey possessed this peculiarity in the highest degree, and so it wasimpossible for him to accept what all the authorities told him, and helooked into the matter for himself. But he was not hasty. He worked athis new views, and he lectured about them at the College of Physiciansfor nine years; he did not print them until he was a man of fiftyyears of age; and when he did print them he accompanied them with ademonstration which has never been shaken, and which will stand till theend of time. What Harvey proved, in short, was this (see Fig. 4)--thateverybody had made a mistake, for want of sufficiently accurateexperimentation as to the actual existence of the fact which everybodyassumed. To anybody who looks at the blood-vessels with an unprejudicedeye it seems so natural that the blood should all come out of the liver, and be distributed by the veins to the different parts of the body, thatnothing can seem simpler or more plain; and consequently no one couldmake up his mind to dispute this apparently obvious assumption. ButHarvey did dispute it; and when he came to investigate the matter hediscovered that it was a profound mistake, and that, all this time, theblood had been moving in just the opposite direction, namely, from thesmall ramifications of the veins towards the right side of the heart. Harvey further found that, in the arteries, the blood, as had previouslybeen known, was travelling from the greater trunks towards theramifications. Moreover, referring to the ideas of Columbus and of Galen(for he was a great student of literature, and did justice to all hispredecessors), Harvey accepts and strengthens their view of the courseof the blood through the lungs, and he shows how it fitted into hisgeneral scheme. If you will follow the course of the arrows in Fig. 4you will see at once that--in accordance with the views of Columbus--theblood passes from the right side of the heart, through the lungs, to theleft side. Then, adds Harvey, with abundant proof, it passes through thearteries to all parts of the body; and then, at the extremities of theirbranches in the different parts of the body, it passes (in what way hecould not tell, for his means of investigation did not allow him to say)into the roots of the vents--then from the roots of the veins it goesinto the trunk and veins--then to the right side of the heart--and thento the lungs, and so on. 

That, you will observe, makes a complete circuit; and it was preciselyhere that the originality of Harvey lay. There never yet has beenproduced, and I do not believe there can be produced, a tittle ofevidence to show that, before his time, any one had the slightestsuspicion that a single drop of blood, starting in the left ventricle ofthe heart, passes through the whole arterial system, comes back throughthe venous system, goes through the lungs, and comes back to the placewhence it started. But that is the circulation of the blood, and it wasexactly this which Harvey was the first man to suspect, to discover, andto demonstrate. 

But this was by no means the only thing Harvey did. He was the firstwho discovered and who demonstrated the true mechanism of the heart'saction. No one, before his time, conceived that the movement of theblood was entirely due to the mechanical action of the heart as a pump. There were all sorts of speculations about the matter, but nobody hadformed this conception, and nobody understood that the so-calledsystole of the heart is a state of active contraction, and the so-calleddiastole is a mere passive dilatation. Even within our own age thatmatter had been discussed. Harvey is as clear as possible about it. Hesays the movement of the blood is entirely due to the contractions ofthe walls of the heart--that it is the propelling apparatus--and allrecent investigation tends to show that he was perfectly right. And fromthis followed the true theory of the pulse. Galen said, as I pointedout just now, that the arteries dilate as bellows, which have an activepower of dilatation and contraction, and not as bags which are blownout and collapse. Harvey said it was exactly the contrary--the arteriesdilate as bags simply because the stroke of the heart propels the bloodinto them; and, when they relax again, they relax as bags which are nolonger stretched, simply because the force of the blow of the heartis spent. Harvey has been demonstrated to be absolutely right in thisstatement of his; and yet, so slow is the progress of truth, that, within my time, the question of the active dilatation of the arterieshas been discussed. 

Thus Harvey's contributions to physiology may be summed up as follows:In the first place, he was the first person who ever imagined, and stillmore who demonstrated, the true course of the circulation of the bloodin the body; in the second place, he was the first person who everunderstood the mechanism of the heart, and comprehended that itscontraction was the cause of the motion of the blood; and thirdly, hewas the first person who took a just view of the nature of the pulse. These are the three great contributions which he made to the science ofphysiology; and I shall not err in saying--I speak in the presence ofdistinguished physiologists, but I am perfectly certain that they willendorse what I say--that upon that foundation the whole of our knowledgeof the human body, with the exception of the motor apparatus and thesense organs, has been gradually built up, and that upon that foundationthe whole rests. And not only does scientific physiology rest uponit, but everything like scientific medicine also rests upon it. Asyou know--I hope it is now a matter of popular knowledge--it is thefoundation of all rational speculation about morbid processes; it isthe only key to the rational interpretation of that commonest ofall indications of disease, the state of the pulse; so that, boththeoretically and practically, this discovery, this demonstration ofHarvey's, has had an effect which is absolutely incalculable, and theconsequences of which will accumulate from age to age until they resultin a complete body of physiological science. 

Fig. 5. --The junction of the arteries and veins by capillary tubes, discovered by Malpighi (A. D. 1664). 

I regret that I am unable to pursue this subject much further; but thereis one point I should mention. In Harvey's time, the microscope washardly invented. It is quite true that in some of his embryologicalresearches he speaks of having made use of a hand glass; but thatwas the most that he seems to have known anything about, or that wasaccessible to him at that day. And so it came about, that, although heexamined the course of the blood in many of the lower animals--watchedthe pulsation of the heart in shrimps, and animals of that kind--henever could put the final coping-stone on his edifice. He did not knowto the day of his death, although quite clear about the fact thatthe arteries and the veins do communicate, how it is that theycommunicate--how it was that the blood of the arteries passed into theveins. One is grieved to think that the grand old man should have gonedown to his tomb without the vast satisfaction it would have given tohim to see what the Italian naturalist Malpighi showed only seven yearslater, in 1664, when he demonstrated, in a living frog, the actualpassage of the blood from the ultimate ramifications of the arteriesinto the veins. But that absolute ocular demonstration of the truth ofthe views he had maintained throughout his life it was not granted toHarvey to see. What he did experience was this: that on the publicationof his doctrines, they were met with the greatest possible opposition;and I have no doubt savage things were uttered in those oldcontroversies, and that a great many people said that these new-fangleddoctrines, reducing living processes to mere mechanism, would sap thefoundations of religion and morality. I do not know for certain thatthey did, but they said things very like it. The first point was toshow that Harvey's views were absolutely untrue; and not being able tosucceed in that, opponents said they were not new; and not being able tosucceed in that, that they didn't matter. That is the usual course withall new discoveries. But Harvey troubled himself very little about thesethings. He remained perfectly quiet; for although reputed a hot-temperedman, he never would have anything to do with controversy if he couldhelp it; and he only replied to one of his antagonists after twentyyears' interval, and then in the most charming spirit of candour andmoderation. But he had the great satisfaction of living to see hisdoctrine accepted upon all sides. At the time of his death, therewas not an anatomical school in Europe in which the doctrine of thecirculation of the blood was not taught in the way in which Harvey hadlaid it down. In that respect he had a happiness which is granted tovery few men. 

I have said that the other great investigation of Harvey is not onewhich can be dealt with to a general audience. It is very complex, andtherefore I must ask you to take my word for it that, although not sofortunate an investigation, not so entirely accordant with later resultsas the doctrine of the circulation; yet that still, this little treatiseof Harvey's has in many directions exerted an influence hardly lessremarkable than that exerted by the Essay upon the Circulation of theBlood. 

And now let me ask your attention to two or three closing remarks. 

If you look back upon that period of about 100 years which commenceswith Harvey's birth--I mean from the year 1578 to 1680 or thereabouts--Ithink you will agree with me, that it constitutes one of the mostremarkable epochs in the whole of that thousand years which wemay roughly reckon as constituting the history of Britain. In thecommencement of that period, we may see, if not the setting, at any ratethe declension of that system of personal rule which had existed underprevious sovereigns, and which, after a brief and spasmodic revival inthe time of George the Third, has now sunk, let us hope, into the limboof forgotten things. The latter part of that 100 years saw the dawnof that system of free government which has grown and flourished, andwhich, if the men of the present day be the worthy descendants of Eliottand Pym, and Hampden and Milton, will go on growing as long as thisrealm lasts. Within that time, one of the strangest phenomena which Ithink I may say any nation has ever manifested arose to its height andfell--I mean that strange and altogether marvellous phenomenon, EnglishPuritanism. Within that time, England had to show statesmen likeBurleigh, Strafford, and Cromwell--I mean men who were real statesmen, and not intriguers, seeking to make a reputation at the expense of thenation. In the course of that time, the nation had begun to throw offthose swarms of hardy colonists which, to the benefit of the world--andas I fancy, in the long run, to the benefit of England herself--havenow become the United States of America; and, during the same epoch, the first foundations were laid of that Indian Empire which, it may be, future generations will not look upon as so happy a product of Englishenterprise and ingenuity. In that time we had poets such as Spenser, Shakespere, and Milton; we had a great philosopher, in Hobbes; and wehad a clever talker about philosophy, in Bacon. In the beginning of theperiod, Harvey revolutionized the biological sciences, and at the end ofit, Newton was preparing the revolution of the physical sciences. I knownot any period of our history--I doubt if there be any period of thehistory of any nation--which has precisely such a record as this toshow for a hundred years. But I do not recall these facts to yourrecollection for a mere vainglorious purpose. I myself am of opinionthat the memory of the great men of a nation is one of its most preciouspossessions--not because we have any right to plume ourselves upon theirhaving existed as a matter of national vanity, but because we have ajust and rational ground of expectation that the race which has broughtforth such products as these may, in good time and under fortunatecircumstances, produce the like again. I am one of those people whodo not believe in the natural decay of nations. I believe, to speakfrankly, though perhaps not quite so politely as I could wish--but Iam getting near the end of my lecture--that the whole theory is aspeculation invented by cowards to excuse knaves. My belief is, that sofar as this old English stock is concerned it has in it as much sapand vitality and power as it had two centuries ago; and that, with duepruning of rotten branches, and due hoeing up of weeds, which will growabout the roots, the like products will be yielded again. The "weeds"to which I refer are mainly three: the first of them is dishonesty, thesecond is sentimentality, and the third is luxury. If William Harvey hadbeen a dishonest man--I mean in the high sense of the word--a man whofailed in the ideal of honesty--he would have believed what it waseasiest to believe--that which he received on the authority of hispredecessors. He would not have felt that his highest duty was to knowof his own knowledge that that which he said he believed was true, andwe should never have had those investigations, pursued through goodreport and evil report, which ended in discoveries so fraught withmagnificent results for science and for man. If Harvey had been asentimentalist--by which I mean a person of false pity, a person whohas not imagination enough to see that great, distant evils may be muchworse than those which we can picture to ourselves, because theyhappen to be immediate and near (for that, I take it, is the essence ofsentimentalism)--if Harvey had been a person of that kind, he, beingone of the kindest men living, would never have pursued those researcheswhich, as he tells us over and over again, he was obliged to pursue inorder to the ascertainment of those facts which have turned out to be ofsuch inestimable value to the human race; and I say, if on such groundshe had failed to do so, he would have failed in his duty to the humanrace. The third point is that Harvey was devoid of care either forwealth, or for riches, or for ambition. The man found a higher idealthan any of these things in the pursuit of truth and the benefit of hisfellow-men. If we all go and do likewise, I think there is no fear forthe decadence of England. I think that our children and our successorswill find themselves in a commonwealth, different it may be from thatfor which Eliott, and Pym, and Hampden struggled, but one which will beidentical in the substance of its aims--great, worthy, and well to livein. 

[Footnote 1: A Lecture delivered in the Free Trade Hall, November 2nd, 1878. ]