In this passage the discoverer's thought rises high, but in the next it stoops again. The next passage is headed "Spirits not from air"; and Harvey says in effect, as I understand his difficult words:—

If spirits are made by concoction out of air, the air is made either thinner or thicker in the process. If made thick, how does it get from the windpipes into the venous artery? If the spirits be thinner than air, how are they held[66] by the tunic of the lung, since this lets pass the pus and serum of empyema?[65]

In the treatise of 1628 Harvey says that Laurentius

"asserts and proves that, in empyema, serosities and pus absorbed from the cavity of the chest into the venous artery may be expelled and got rid of with the urine and fæces through the left ventricle of the heart and the arteries."[67]

Harvey's argument in his note-book continues thus:—

"How, since mixture consists in the union of altered matters, can air be thoroughly mixed and made one with blood? What is that which mixes and alters? If it be heat, the air is made thinner thereby. If it be urged that the air is thickened by cold during preparation (which is impossible in the lungs), then Aristotle's[68] argument holds good: if spirits be from the air, how about fishes, which are agile and abound in spirits?"[69]

At this point we may call to mind passages in the introduction to Harvey's treatise of 1628, published more than eleven years after he had written the notes which we are now studying. In one of these passages he speaks of what is now called the pulmonary vein, saying:—

"If it be contended that fumes and air pass to and fro by this road, as through the bronchia of the lungs, why can we find neither air nor fumes on dissection, when the venous artery has been cut out or cut into? And how comes it that we always see the aforesaid venous artery to be full of thick blood and never of air, while we perceive that there is air remaining in the lungs?"[70]

Immediately after the foregoing passage Harvey says that should an experimenter

"make a cut in the trachea of a living dog, forcibly fill the lungs with air by means of a bellows and, when they have been distended, apply a firm ligature, on opening the chest shortly after, he would find great abundance of air in the lungs, up to their outermost tunic, but none at all in the venous artery or in the left ventricle of the heart. If in the living dog the heart drew air out of the lungs or the lungs transmitted it, much more ought they to do so in this experiment. Who, indeed, could doubt that even in a dissection, if the lungs of a dead body had been inflated, air would enter at once, as aforesaid, did any passages exist?"[71]

Yet we have found Aristotle, more than nineteen centuries before Harvey, recognizing that no passages are needed for the transfer of air out of the windpipe, and saying, of the channels from the heart, that "it is by contact that they receive the breath[72] and transmit it to the heart."[73] Moreover, sixty-nine years before Harvey's publication Columbus had repeatedly recommended the experiment of opening the venous artery[20] in a living dog and noting that the "said venous artery" is full of blood, not of air or fumes. But Columbus held this observation rather to confirm than to disprove his doctrine that the blood in the venous artery is imbued with vital spirits derived in the lungs from the substance of the air. Indeed, he goes so far as to call the contents of this vessel "modified blood and air."[74] In this matter the earlier observer, Columbus, shows keener insight than the later, Harvey.

Decidedly, however, the stage waits for the chemists, despite Harvey's poor opinion of them. Despite that poor opinion, too, Harvey himself turns to making chemical conjectures in the next passage of his note-book, to the study of which latter we will now return. The passage is as follows:—

"Conclusion. Opinion of W. H.

"In animals in which lungs are fleshy and full of blood these concoct the blood, seeing that spirits and blood are one thing, in the same way that the liver does and by reason of the same arguments; indeed, the lungs may rather detain fatty and oleaginous vapor by a cooling process, as oil or balsam or nutritious fat is cooled in alembic and serpentina"[75]—

"alembic" and "serpentina" answering to the "still" and "worm" of the modern distiller. Harvey, therefore, utilizes the Galenic analogy between concoction in the lungs and that of the blood and the vapors thereof, rejecting not only Galen's preliminary concoction of air into spirits in the lungs, but also Columbus's union in the lungs of blood with spirits produced in the lungs themselves out of air. Of the entrance of "the substance of air" into the blood Harvey makes emphatic denial and, by so doing, reduces the spirits either to emanations from ingredients of the body itself (thus reminding us of Aristotle), or to a mere name with which to label qualities of the blood, in treating of which he often uses the word "spirits" as a current term. Naturally, therefore, where in his lecture notes he treats of the spirits in relation to the brain and nerves his conclusions are not clearly defined, but seem consistent with his views as to the spirits in the blood, though his jotted words are not very easy to understand. On this subject he refers by name to Galen, three alternatives discussed by whom appear to be reviewed by Harvey, viz.: that sensation and motion result either from a progression from elsewhere of spirits in substance along and within the nerves; or from a vibration of spirits in substance which have their native seat within the nerves; or, lastly, from no movement of a substance, but from a transfer of "faculty" along the nerves by means of progressive qualitative alteration thereof, "such as is produced in air by the brightness of the sun."[76] Of these three alternatives, the last seems to commend itself most to Harvey, as we should expect; the second, next; and the first, not at all;—that is, if one may so interpret the following brief passage of his lecture notes:—

"I believe that in the nerves there is no progression of spirits, but irradiation; and that the actions from which sensation and motion result are brought about as light is in air, perhaps as the flux and reflux of the sea."[77]

Also we find Harvey long years afterward saying to Riolanus:—

"Moreover, the spirits, animal, natural, vital, which dwell, contained within blind windings, in solid parts, to wit, in ligaments and nerves (especially if there be so many kinds),—these spirits are not to be regarded as so many diverse aëreal forms, nor as so many kinds of vapors."[78]

In Harvey's lecture notes the subject of respiration is brought to an end with an abrupt interrogation, which seems to reveal a sudden return of doubt as to whether too much may not have been conceded in admitting a pulmonary concoction of any sort. We read:—

"N.B. If the blood receive concoction in the lungs, why does it not traverse the lungs in the embryo?"[79]

It would seem to be Harvey's tendency to adhere to the view which limited the use of respiration entirely to the cooling and ventilation of the innate heat, by which according to ancient doctrine the heart was the central hearth, embedded in the cooling and ventilating lungs; although this ancient doctrine tallied well in most eyes with the belief that only a portion of the blood ever entered the heart at all.[80] In the first of the two Exercises which Harvey, when seventy years old, in 1649, addressed to Riolanus in defense of the circulation, the ancient respiratory cooling and ventilation take their place again as follows:—

"Thus by the aid of two extremes, viz.: cold and heat, is the temperature of the animal body retained at its mean. For as the air inspired tempers the too great heat of the blood in the lungs and centre of the body and effects the expulsion of suffocating fumes, so in its turn does the hot blood, thrown through the arteries into the entire body, cherish and nourish and keep alive all the extremities, preventing extinction due to the power of external cold."[81]

In none of the writings of his old age does Harvey deal expressly with concoction in the lungs, or more than cursorily with the entrance of the substance of air into the blood. But he repeatedly and emphatically reaffirms that blood and spirits are one thing;[82] he even declares the blood in comparison with the other parts of the body to be "possessed of powers of action beyond all the rest, and therefore, in virtue of its preëminence, meriting the title of spirit."[83] He castigates those who give the rein to overmuch speculation about the spirits. We learn that some suppose that the spirits "are engendered and are fed and increased from the thinner part of the blood"; that others suppose "the primigenial moisture" to engender and support them.[84] Then there are "those who tell us that the spirits are formed in the heart, being compounded of the vapours or exhalations of the blood (excited either by the heat of the heart or the agitation) and the inspired air"[85]—the Galenic doctrine.

"Such spirits," says Harvey of these last mentioned, "are rather to be regarded as fumes and excrementitious effluvia of the blood and body, like odours, than as natural artificers; ... whence it seems probable also that pulmonary expiration is for the ventilation and purifying of the blood by the breathing out of these; while inspiration is in order that the blood, in passing through between the two ventricles of the heart, may be tempered by the ambient cold; lest the blood, being hot and swollen, blown up in a sort of ferment, like milk and honey boiling up, should so distend the lungs that the animal would be suffocated."[86]

As we read these words, published in Harvey's old age, we recollect the following words, written in his note-book more than thirty-three years before, viz.: "So there is cooling and ventilation of the native heat, ventilation especially."[87]

We may recall also that the preservation of the native heat had sufficed to explain respiration to Harvey's ancient teacher, Aristotle, while the tenor of Aristotle's genuine works well accords with the following dictum which we have found in Harvey's note-book: "Spirits not from air." Yet the more firmly this dictum was upheld, and the more simply Aristotelian in principle did Harvey's doctrine of respiration remain, so much the less called for must have seemed that swift and endlessly repeated passage through the lungs of the whole mass of the blood, which was involved in the Harveian circulation.

In the actual phenomena of respiration, however, positive obstacles confronted the doctrine of the circulation which were harder to surmount than cobwebs of speculation, or than the mere question "cui bono" which latter the steadfast observer could simply wave aside. Spirits or no spirits, there were opponents of the circulation, even in Harvey's old age, who insisted that the blood in the arteries was so different from the blood in the veins that the same blood could not be changing perpetually from arterial to venous, and vice versa. There was always that stubborn difference of color, plainly to be seen in man and beast, but so hard to account for in Harvey's day. Therefore, we find Harvey leaving the realm of subtleties and taking up his old weapon of demonstration, in order to minimize the differences between arterial and venous blood. Twenty years after the publication of his discovery he says to Riolanus:—

"You may also perform another experiment at the same time. If you fill two cups of the same measurement with blood, one with that which issues by leaps from an artery, the other with venous blood from a vein of the same animal, you can observe the sensible differences between the two, both immediately and later, when the blood in either cup has become coagulated and cold. This experiment will contradict those who pretend that the blood in the arteries is of one kind, that in the veins of another, on the ground that that in the arteries is more florid and seethes and is blown up with copious spirits, I know not how, like milk or honey boiling upon the fire, swelling and filling a larger space. For, were the blood which is thrown from the left ventricle of the heart into the arteries fermented thus into a frothy and flatulent condition, so that a drop or two distended the whole cavity of the aorta, unquestionably, upon the subsidence of this fermentation, the volume of the blood would return to that of a few drops (and this is, indeed, the reason that some assign for the empty state of the arteries in the dead body); and this would be apparent in the cup which is full of arterial blood, for so we find it to happen in milk and honey when they come to cool. But if in both cups you find blood nearly of the same colour, not of very different consistency in the coagulated state, forcing out serum in the same manner and filling each cup to the same height when cold that it did when hot, this will be enough for any one to rest his faith upon, and afford argument enough, I think, for rejecting the dreams of certain people. On investigation sense and reason alike assure us that the blood of the left ventricle is not of a different kind from that of the right.... The blood, then, when imbued with spirits to the utmost, is not swollen with them, or fermented or blown up so as to crave and require more ample room (as can be determined with the greatest certainty on trial by the measurement of the cups); we should rather understand this blood to be possessed, after the manner of wine, of greater strength, and of an impetus to action and effectiveness, in accordance with the view of Hippocrates.

"So the blood in the arteries is the same as that in the veins; even though the former be acknowledged more spirituous and possessed of greater vital force; but the blood in the arteries is not converted into something more aëreal or rendered more vaporous; as though there were no spirits not aëreal, nor anything which gives an impetus except wind and flatulence."[88]

It is well, one may be inclined to mutter, as one reads this, but how about the color? It may be nearly the same, but certainly there is a difference. In his book "On Generation" Harvey himself describes in more detail the changes which occur in shed blood on standing, and says: "Of the red parts the upper are more florid, those below are blackish." In the same description he refers shortly after to "the florid and ruddy part which is commonly thought to be arterial blood."[89] The words last quoted evidently refer to the upper part of coagulating blood as commonly seen. This in medical practice would be blood drawn from a vein, and Harvey says nothing of arteriotomy in this passage. Indeed, he refers in the context to venesection; and earlier in the same chapter he wrote: "Physicians observe only human blood, and this shed by venesection into a basin, and coagulated."[90]

The foregoing passages show at once that opinions had been clarified very little by the suggestive change of color caused in shed blood by contact with air. Years before, in jotting down his lecture notes, Harvey had noted that the arterial blood is redder;[91] Galen had known it;[92] it must always have been known. In 1649 Harvey wrote:—

"Three things are especially apt to give rise to this opinion of the diversity of the blood: the first is that the blood which is drawn in arteriotomy is more florid....[93] Whenever and wherever blood issues through a narrow orifice it is strained, as it were, and the thinner and lighter part, which usually swims on top and is the more penetrating, is emitted."[94]

A number of observations follow, of appearances noted in nosebleed, in the use of leeches, in cupping, and in blood-letting from veins and arteries. All these appearances are adduced in support of the view that it is the straining of the blood which renders it more florid, and they all show that the brightening of the color of shed blood on exposure to air served only to lead Harvey off on a false scent. Continuing he refers, as follows, to direct inspection of the dissected lungs:—

"The blood is found to be much more florid within the lungs and after it is squeezed out of them, than in the arteries."[95]

A few pages farther on he states, categorically, the false conclusion to which he has been driven, saying:—

"It is no less plain why the blood of the lungs is so ruddy; for it is thinner, because there it is filtered through."[96]

Nothing indicates better Harvey's readiness to minimize the essential differences between venous and arterial blood than a passage in the treatise of 1628, in which he says that, compared with the left ventricle, the right ventricle "is of greater capacity, that it may supply not only matter to the left ventricle, but also nourishment to the lungs."[97] It should be remembered that, in Harvey's day, the so-called bronchial arteries were still unknown, through which the tissues of the lungs are supplied with arterial blood from the aorta.[98] Not only Columbus,[99] but even Galen,[100] had each devised an erroneous way in which to provide the lungs with "spirituous" or "vital" blood, in addition to the venous blood from the right ventricle; but Harvey is obviously content to let the latter suffice for their nutrition.

What has gone before indicates how erroneous it is to speak of the pulmonary transit, as Columbus had set it forth in 1559, nineteen years before Harvey's birth, as though Columbus were in some sort a sharer in the discovery of the circulation. Those who so speak fail to note the difference between blood and the blood. Although Columbus girded at Galen and corrected him, Columbus's pulmonary transit of a fraction of the blood by curing more than one defect of the Galenic doctrine strengthened the erroneous Galenic physiology of the blood-movement. Of these larger features Columbus not only was no enemy, but remained a devoted adherent. His doctrine certainly paved the way for Harvey's, but in no more immediate sense than did Galen's doctrine that blood is naturally contained in the arteries.[80]

Indeed, Harvey categorically stated that the movement of blood through the lungs had nothing to do with his discovery. In a Latin letter from London written in 1651 to P. M. Siegel in Hamburg, Harvey says in his old age:—

"Meantime, as Riolanus uses his utmost efforts to oppose the passage of blood into the left ventricle through the lungs, and brings it all hither through the septum, and so vaunts himself as having upset the very foundation of the Harveian circulation, (although I have nowhere laid that down as a foundation for my circulation; for the blood fetches a circuit in very many red-blooded animals in which no lungs are to be found), it may be well here to relate an experiment which I lately tried in the presence of several of my colleagues, and from the cogency of which there is no escape."[101]

The parenthesis certainly is a striking one.

No less striking is the last word published by Harvey about respiration. We have heard him deny the entrance of air into the blood and doubt the occurrence of any concoction in the lungs. Now we shall hear him throw over even the cooling of the innate heat, a respiratory doctrine to which he has seemed hitherto to hold with conviction. In the essay "On Parturition" published in 1651 with the treatise "On Generation," he says:—

"In the meantime I would propose this question to the learned: How comes it that the fœtus continues in its mother's womb after the seventh month? If brought forth at that time it breathes at will, indeed could not survive one little hour without breathing; yet, as I have said, if it remain in the womb it keeps alive and well beyond the ninth month without the aid of respiration.... Whoso shall attend carefully to these things and consider more closely the nature of air, will, I think, readily grant that air is given to animals neither for cooling nor as nutriment; for it is a fact that after the fœtus has once drawn breath it may be suffocated more quickly than when entirely excluded from the air; as though heat were unkindled by air within the fœtus rather than allayed. Thus much, merely by the way, on the subject of respiration; perhaps I shall treat of it more fully in its proper place. Surely a more knotty subject could hardly be found, as the arguments on both sides are very evenly balanced."[102]

So we find Harvey in his old age induced by lifelong study to question, if not deny, even the cooling effects of respiration, and to end with a practical confession of ignorance. Instead, therefore, of the circulation and its swiftness being explained by the urgent need of "the substance of the air" experienced by certain tissues, that movement of the whole mass of the blood through the lungs, which was so novel a physiological fact, does not seem to have affected his view of the problems of respiration. Nor could he properly explain the respiratory change in the color of the blood, which seemed to support the ancient doctrine that the blood is of two different kinds. Since he could not invoke respiration to elucidate the circulation and its rapidity, and since he himself declared that such rapidity could not be needed for the simple feeding of the tissues, what was left to be invoked? It is no wonder that eight years[103] after the publication of his discovery Harvey denied that he had ever seriously undertaken to explain the use of the circulation; that at the end of thirteen years more he repeated this denial in his old age;[104] although he had not refrained from expressing such conjectures as must always be evoked in the mind of a great observer by a discovery of the first importance made by himself. Yet the phenomena of the very circulation used were so striking as to cry aloud for elucidation; for Harvey's own clinching statement that the heart drives into the aorta at least one thousand drachms of blood in half an hour,[105] this reductio ad absurdum, which cut the ground from under the feet of his opponents, left him helpless in his turn to account for the need of so huge a flooding of the arteries.

Since it was not to be swiftly altered in the lungs that the whole mass of the blood hurried back from all parts of the chest, what then?

CHAPTER IV

THE CIRCULATION AND THE ARISTOTELIAN PRIMACY OF THE HEART

It has been stated already that the first announcement of the circulation is to be found in Harvey's lecture notes. The following is the text of the memorable passage in question, which I have translated from Harvey's Latin. He says:—

"It is proved by the structure of the heart that the blood is perpetually transferred through the lungs into the aorta, as by two clacks of a water-bellows to rayse water. It is proved by the ligature that there is a transit of the blood from the arteries to the veins; whereby it is demonstrated that a perpetual movement of the blood in a circle is brought about by the beat of the heart. Is this for the sake of nutrition, or of the better preservation of the blood and members by infusion of heat, the blood in turn being cooled by heating the members and heated by the heart?"[106]

The words "as by two clacks of a water-bellows to rayse water" are Harvey's own racy English, embedded in his Latin text. The "ligature" is the flat band which is tied about the upper arm when bleeding from a vein is to be practised at the bend of the elbow. The Hippocratic physicians called this band a "taenia,"[107] and even in their day it was known to hasten the flow of blood from the opened vein when applied as above stated, but yet to check the flow if tied too tight. This clinical observation had awaited a rational explanation for more than nineteen centuries.[108]

Our most immediate interest in the foregoing passage lies in this: that on the very same page, with the few clear simple words which tell for the first time of Harvey's facts and proofs, he has briefly written down conjectures as to the meaning of the circulation. These are as strikingly put as certain jottings are obscure which deal on a neighboring page with some possible meanings of the heart-beat.[109] In neither group of conjectures do the functions of the lungs play a part; but the discoverer asks himself whether it be not to revisit the heat of the heart that the whole mass of the blood circles back to the chest in its Harveian course! More than thirty-two years after the date of Harvey's note-book Harvey wrote to Riolanus:—

"There are some who consider that as no impulsion of nutriment is required for the nutrition of plants, their particles attracting little by little whatever they need to replace what they have lost, so in animals there is no need of any impulsion, the vegetative faculty in both working alike. But there is a difference. In animals a perpetual flow of warmth is required to cherish the members, to keep them alive by the aid of vivifying heat, and to restore parts injured from without. It is not merely nutrition that needs to be provided for."[110]

In the first Exercise to Riolanus Harvey had touched also upon the use of the circulation, interweaving this doctrine of heat with the doctrine of respiration as he then held it, in a passage the last part of which I have quoted already. Quoted more fully he says:—

"And this, indeed, is the principal use and end of the circulation, for which the blood revolves with perpetual influence in its ceaseless course and is driven along its circuit: namely, that all the parts in dependence upon the blood may be kept alive by the primary innate heat and in their state of vital and vegetative being, and may perform all their functions; whilst, to use the language of physiologists, they are sustained and actuated by the inflowing heat and vital spirits. Thus by the aid of two extremes, viz.: cold and heat, is the temperature of the animal body retained at its mean. For as the air inspired tempers the too great heat of the blood in the lungs and center of the body and effects the expulsion of suffocating fumes, so in its turn does the hot blood, thrown through the arteries into the entire body, cherish and nourish and keep alive all the extremities, preventing extinction due to the power of external cold."[111]

"The innate fire is not in the right ventricle," a Hippocratic author had written, who had written also that the wall of the left ventricle is dense, to guard the strength of the heat.[112] Aristotle, too, had placed in the heart the "origin" of the "natural innate heat";[113] had likened the heart to "the hearth on which shall lie the natural kindling, well protected also, as being the acropolis of the body."[114] At a later day Galen had affirmed the same doctrine.[115]

Let us turn now to the famous treatise of 1628, published twelve years after the note-book had been written. In the chapter in which Harvey says "I tremble lest I have mankind at large for my enemies" and then publishes and names the circulation,—in this chapter, before passing to his proofs, he published the following words which resound in a way very different from the simplicity of the note-book:—

"So probably it may come to pass in the body through the movement of the blood that all the parts are nourished, cherished, quickened, by the hotter, perfected, vaporous, spirituous, and, so to speak, alimentive blood; that the blood, on the other hand, is cooled, coagulated, and rendered, as it were, effete in the parts; whence it returns to its origin, namely, the heart, as to its fountain, or the hearth of the body, to regain perfection. There by the potent and fervid natural heat, a treasury of life, as it were, the blood is liquefied anew and becomes pregnant with spirits and, so to speak, with balsam. Thence the blood is distributed again; and all this depends upon the motion and pulsation of the heart.

"The heart, therefore, is the origin of life and the sun of the microcosm, even as the sun in his turn might well be called the heart of the world; by the vigor and pulsation of the heart the blood is moved, perfected, quickened, and delivered from corruption and thickening; and the function of nourishing, cherishing, quickening the entire body is performed by that intimate hearth, the heart, the foundation of life, the author of all. But of these matters more conveniently when I shall speculate as to the final cause of motion such as this."[116]

Upon this florid passage follow the classic six chapters which bring forward with such power and calm the proofs of the circulation. These are succeeded in their turn by words which echo their sobriety, as follows:—

"It will not be beside the question to show also from certain familiar reasonings, that the circulation is both convenient and necessary. In the first place, since death is corruption from deficiency of heat[117] and since all living things are warm, all dying things cold, the heat requires a seat and origin, a home and hearth, as it were, in which the tinder of nature, the first beginning of the innate fire, may be contained and preserved; a place from which, as from their origin, heat and life may flow out into all the parts, whence nutriment may come and upon which concoction and nutrition and all quickening may depend. That this place is the heart, that this is the origin of life as aforesaid, I should hope that none would doubt.

"Hence the blood has need of motion, of motion such that it may return to the heart; for, if sent to the outer parts of the body, far from its source,[118] and left unmoved, it would become coagulated. Heat and spirits are seen to be generated and preserved in all by motion, to vanish if quiet supervene. Therefore, the blood, thickened or stiffened by the cold of the extremities and of the ambient [air] and destitute of spirits, as in the dead, must needs return to its source and origin in order to keep itself whole, to seek thence and repair again its heat and spirits."...[119]

"Moreover," Harvey says, a page farther on, "since all animals live by nutriment concocted in their interior, it is necessary that the concoction and distribution thereof be perfect; and, further, that a place and receptacle exist where the nutriment may be perfected and whence it may be led off to the several members. Now this place is the heart, for it alone of all the parts contains blood for the public use in its cavities, the auricles and ventricles, as in cisterns and storehouse; not merely blood for its private use in the coronary vein and artery."[120]

In the next chapter we obtain glimpses of the pathological relations of this physiology. Harvey brings forward tertian fever as a case in point, explaining that the febrile paroxysm is produced when

"the preternatural heat which has been kindled in the heart is diffused throughout the entire body by way of the arteries, together with the morbific matter which thus is evaporated and dissolved by nature."[121]

As a student of the Greek science reads the foregoing passages, he clearly sees that the new wine of the circulating blood is poured into the old bottles of the Aristotelian physiology; and Harvey tells us so himself, in the last chapter of his most famous treatise. He says:—

"No less should we agree with Aristotle as to the sovereignty of the heart, in dealing with the following and similar questions: Does it receive motion and sensation from the brain, blood from the liver; or is it the origin of the veins and of the blood? For they who try to refute him leave out, or do not grasp, the main argument, which is that the heart is the first part to exist and has in it blood, life, sensation, motion, before the brain or the liver has been made or is clearly to be distinguished, or at least before either can perform any function. So the heart with its own proper organs constructed for motion—as it were, an internal animal—is the earlier formed; and, this being the first made part, it is the will of nature that thereafter the entire animal be made, nourished, preserved, perfected by the heart to be its achievement and abode. The heart is governor everywhere, like the chief in a commonwealth with whom is lodged the first and highest authority. In an animal all power is derived from and depends upon the heart as its origin and foundation."[122]

The main argument, which is that the heart is the first part to exist, is simply the argument from the development of the embryo in the hen's egg. The study of this development day by day had been recommended by one of the Hippocratic writers,[123] and Aristotle had laid stress upon the changes in the embryo during incubation.[124] Harvey, in his turn, had studied them carefully. The ancients could have made their observations only with the naked eye, but Harvey had the aid of a simple lens, though of nothing approaching in power to a microscope.[125] In the treatise of 1628 he speaks as follows of what he thus observed:—

"If you turn to the formation of the chick in the egg, the first thing to exist therein, as I have said, is a mere vesicle, or auricle, or pulsating drop of blood. Afterward, when growth has gone on, the heart is completed.... In a hen's egg after four or five days of incubation I have shown the visible presence of the rudiment of the chick in the form of a little cloud; in an egg, that is, which had been immersed in clear tepid water after removal of the shell. In the middle of the aforesaid little cloud there was a palpitating bloody point, so fine that in contracting it disappeared and became invisible, but reappeared on its relaxation, looking like the point of a needle, and of a ruddy color; so that being now visible and now invisible, as though now existent and now non-existent, it evinced palpitation and the beginning of life."[126]

In the same treatise Harvey promises to publish more observations

"on the formation of the fœtus, where numerous problems of the following order can find a place: Why should this point be made or perfected earlier, that later? As regards the dominance of the members: Which part is the cause of the other? There are very many problems connected with the heart, such as: Why should it be the first thing (as Aristotle says in his third book on the parts of animals)[127] to acquire consistency, and be seen possessed of life, motion, and sensation, before anything has been perfected in the rest of the body? And in like manner regarding the blood: Why is it before all, and how possessed of the beginnings[128] of life and of the animal, and of the craving to move and be impelled hither and thither, to which end the heart would seem to have been made?"[129]

In Harvey's celebrated treatise, despite various frank questionings by the way, such as that just quoted about the blood, he so frankly follows in the footsteps of "the master of them that know" that Aristotle need not be cited at length to prove the fact. To Aristotle are largely due Harvey's references to the heart as the central source of indispensable vital heat; his references to aliment perfected in the heart; his blending of psychological doctrines with the doctrine of the movement of the blood. Therefore, a brief account of how this became possible will be germane.

When an ancient observer looked with the naked eye at the very early embryo of the fowl, he distinguished at first only a blood-red point, which pulsated, or "leapt." This Aristotle judged to be the heart, containing blood before any blood-vessel had shown itself and before blood was visible in any other part. Very soon, however, two vessels containing blood were seen, according to him, to extend from the rudimentary heart toward the periphery. From these and other considerations Aristotle inferred that both the blood and all its containing vessels owe their first origin to the heart; and that throughout life the liquid made elsewhere from the food enters the heart, there to be perfected into blood by the action of the vital innate heat, of which, as we have seen, he held the fiery central hearth to be within the heart. Naturally, therefore, he believed the blood not to be hot of itself, but to acquire its vivifying heat at the heart, the pulsation of which he held to be caused directly by the seething of the blood within. When thus perfected and charged with heat the blood, according to him, is distributed from the heart through the vena cava as well as the aorta. These great vessels and their subdivisions Aristotle distinguished anatomically; but he made no serious physiological distinction between what we call the veins and the arteries, and, himself, applied the word "artery" to the windpipe only. As to the cavities and contents of the heart, even as to the number of its cavities, he had obscure, complex, and erroneous ideas, and of the valves he knew nothing. He recognized no essential differences between the matters distributed by way of the vena cava and by way of the aorta, all being, alike, one thing, blood; though the blood was hotter or cooler, thinner or thicker, purer or cruder, in different regions or parts of the body, in different sets of vessels, in different cavities of the heart, or at different times in the same place.

We have seen already that, in the genuine works of Aristotle, there is no sign that what we call the tissues of the adult require or receive a derivative of the air, whether crudely mingled with the blood in the earlier Hippocratic way, or separate in Erasistratean fashion, or in the form of such "spirituous blood" as Galen afterward accepted. We have seen that the air which Aristotle believed to enter the heart for cooling purposes, cannot be traced beyond it; that whatever spirits may exist in the body for him, would seem to be either of the nature of vapor produced within the body itself, or of a nature quite indeterminate.[130]

The living egg of the hen has had a vast deal to do with the history of psychology as well as of physiology. It is partly owing to what Aristotle believed to go on in the egg that we speak to-day of good hearts and bad hearts—even of sweethearts. Aristotle knew nothing of the nerves, and, therefore, could reasonably fail to find conclusive evidence that the brain and spinal cord had to do with what we call nervous functions. So he fell back upon a doctrine at least as old as the Iliad,[131] and made a psychological center of the heart. This being proved, for Aristotle, largely by its demeanor in the early embryo, to be the life-long source of the nutritive blood; and being, for him, the central hearth of the heat by means of which the blood is perfected and warmed; he held it a matter of necessity that in the heart should dwell the so-called "nutritive soul"; that is, the faculty which uses as its most immediate instrument the "innate," "natural," "vital," "psychical," heat, to bring about nutrition, growth, and generation. He says:—

"It is impossible that the other faculties of the soul should exist without the nutritive, or these without the natural fire; for in this has nature set that faculty aglow."[132]

Dealing with these other faculties, he sees that there must be an organ where the results of sight, hearing, and the other senses, are compared; and deliberately discussing and rejecting the claims made for the brain he makes the heart this "common sense-organ of all the sense-organs," as he styles it. He says:—

"If in all the creatures the seat of life is in this part, it is clear that here also must the origin of sensation be; for we say that the body has life because it is an animal, but we say that it is animal because it has sensation."[133]

Less hollow rings the argument in the modern ear, when the ancient thinker bases it on conclusions drawn from observation. We learn from him that only those parts are sensitive which contain blood, as opposed to hair and nails, or even to the blood, if taken by itself. We learn, therefore, that as the heart of the embryo is the first part to contain blood, it is the first part to be sensitive and hence is the central source of sensation. Moreover, Aristotle, like Plato,[134] knowing nothing of the nerves, judges the blood-vessels to be sensory paths; and blood-vessels connect, not only the sensitive flesh, but all the more special sense-organs with the heart. Such is the outline of the reasons why Aristotle held the heart to be the lifelong seat, not only of the "nutritive soul," but of the "sensory soul" as well.

Pain, pleasure, and desire would naturally dwell beside sensation in the heart, which Aristotle held to be obviously the seat of the emotions, as proved by its palpitation when they are stirred. Moreover, it is desire, seated in the heart, which incites to action, to motion, movement thus resulting from sensation; and, in general, "the movements" of every sense both begin and end at the heart; the word here translated "movement"[135] being used, in the technical diction of Aristotle, to include not only the "molar motion" of modern parlance, but also subtle forms of change of state. Further, in the early embryo the heart itself is plainly the first part which possesses motion; it visibly taking the lead in this, moving "as though itself an animal." The pulsating movements of the heart are the direct effects of the seething and vaporization within it; while, in the respiratory movements, the chest wall is pushed out by an expansion due to the vital heat, whose cardiac hearth the lungs inclose, and then follows inward a contraction due to the cooling air which has been drawn into the expanding lungs. As the bodily movements, in general, are "brought about by drawing and slackening" and originate at the heart, it is appropriate that the heart contains tendinous structures[136] within itself; "for it needs the service and strength" of such.[137] It is too, in a sense, the origin of the discontinuous tendinous and ligamentous structures of the body. Aristotle's doctrine of the heart as the source of motion seems especially vague. But, hardy thinker though he was, he scarcely could be definite on this subject, even in speculation. He knew that heat expands and cold contracts; he recognized the force which, as he believed, confined or compressed vapor exerts in living bodies, not only in health but in disease; and he knew the strength imparted to bodily effort by holding the breath. His genuine writings, however, bring forward no modus operandi, except in the case of respiration and of the movements of the heart itself. We are given no inkling as to how the tendons are normally drawn and slackened in obedience to the will, for the true function of muscle was unknown to Aristotle (Harvey to the contrary notwithstanding),[138] and the blood-vessels were the only continuous special paths between center and periphery which Aristotle could make out. In his time, as we have seen, the nerves had not been distinguished, even anatomically, from the bands and cords of the ligaments and tendons.

So, for Aristotle, the nutritive, sensory, and motor faculties, the desires and emotions, in short all the souls or parts of the soul (to use the ancient phraseology) that are not the most exalted, dwell in fire within the heart, suitably and honorably placed at the central "acropolis." To the divine mind of man, on the other hand, he does not assign a definite special dwelling-place within the body.

Harvey differed often and widely from Aristotle. Yet even in his old age he wrote: "The authority of Aristotle has always such weight with me that I never think of differing from him inconsiderately."[139] Cannot one fancy, may not one conjecture, that in the eyes of the discoverer of the circulation his great discovery, fundamental, new, and original, as he rightly claimed it to be, may at times have seemed to constitute a thorough correcting and filling in of a rough sketch dashed off at the Lyceum? Let us see.

Aristotle had no conception of anything resembling a circulation of the blood, nor any definite mechanical ideas as to its movement. While the vena cava as well as the aorta received blood from his valveless heart and yielded it to the body at large, blood ebbed back to the heart during sleep, and the warm nutrient liquid which the vena cava and the aorta yielded to the tissues had previously entered the heart continuously but in an imperfect state through both of these great vessels, to go forth again through both, perfected into blood and heated, with no perplexing differences of color noted between that in the great vein and that in the aorta. The relations between the food, the blood, the heart, and the body at large, though recognized to be complex, may well have presented themselves to Aristotle with something of the vagueness with which the relations between the food, the liquids, the contractile vacuole, and the living substance of a protozoön, present themselves to us. If the heart, retaining its Aristotelian powers, were found to receive the blood imperfect or impaired, but to receive it by the veins only, and to send it out, but only by the arteries, warmed and perfected or restored to perfection at its Aristotelian source; what have we but the systemic part of the circulation, as it may have pictured itself sometimes to Harvey?[140]

CHAPTER V

PHYSICIANS versus PHILOSOPHERS—HARVEY FOR THE PHILOSOPHERS

Thus it is striking to find Harvey, as the champion against Galen of a view essentially Aristotelian, entering the field of controversy where ancient Greek still met ancient Greek in the modern Europe of 1628.

The discoveries of the nerves and the valves of the heart had made great difficulties for the Aristotelian psychology and physiology shortly after Aristotle's time. We have seen that the semilunar valves were described, and their use noted, in a treatise included in the Hippocratic collection;[141] and all the valves, both arterial and auriculo-ventricular, were well recognized by Erasistratus, whose acquaintance we have made already, and who flourished about 300 B.C., Aristotle having died in 322 B.C. Erasistratus, we remember, was more than four centuries earlier than Galen and more than nineteen centuries earlier than Harvey.

That the heart throughout life is not only the source of the perfected blood, but gives out blood to the vena cava for distribution, had been rendered a hard saying, especially by the recognition of the tricuspid valve.[142] Galen, however, like the somewhat earlier Greek physician Aretæus, the Cappadocian,[143] was not confronted by this difficulty, for they both adhered to an ancient doctrine to be found in the Hippocratic treatise "On Nourishment," and there sketched with mingled clearness and vagueness in the following pithy saying:—

"Root of the veins, the liver; root of the arteries, the heart. Out of these wander into all parts blood and spirits, and through these heat comes in."[144]

Obviously the doctrine here foreshadowed was quite irreconcilable with the views of Aristotle.

In studying the works of Harvey and of his contemporaries and predecessors it must be borne in mind that, from ancient times past the time of Harvey to more modern days, the word "heart" was very commonly used by physicians and men of science to mean simply the ventricular mass, without the auricles, which were reckoned in with the great vessels. In slaughterhouses the word is still used in this ancient sense. Harvey's practice was fluctuating; for the word is used by him sometimes to mean the ventricular mass only, sometimes, as in the science of to-day, to mean the ventricular mass and the auricles taken together.

According to the more detailed views of Galen and his school the blood was perfected and had its central source not in the heart, but in the liver, to which the portal vein brought a cruder liquid derived from the products of digestion. In the liver the veins also originated, while the arteries originated at the heart. The blood left its source in the liver, by way of the roots of the venous system, that is, by the hepatic veins of modern anatomy. From these it entered the great venous trunk, the vena cava, a vessel which comprised the inferior cava, the right auricle, and the superior cava of our present nomenclature. Upon leaving the liver the blood at once divided into two sharply diverging streams, one flowing directly downward through the vena cava, the belly, and the lower extremities; the other stream flowing directly upward through the vena cava to the chest, the upper extremities, and the head. Therefore, that part of the vena cava which we call the right auricle simply formed a part of the upward pathway of the blood, at a place where some of the blood left this upward pathway and flowed through a side opening into the right ventricle. This ventricle, therefore, received only a fraction of that portion of the blood which ascended from the liver. The rest of the ascending blood mounted in the vena cava past the right opening which led into the ventricle and, having traversed thus what we call the right auricle, entered and traversed what we call the superior vena cava, to be distributed to the veins and tissues of the arms and head. Of the fraction of the blood that entered the right ventricle a part went to the lungs simply for their nutrition, by the "arterial vein"—the pulmonary artery of modern parlance—and a part percolated in a refined condition through pores of the septum from the right ventricle to the left, to be worked up there with the vital spirits and thus become the basis of the spirituous blood of the arteries. From the left ventricle this spirituous blood went to the body at large by way of the arteries. There is no evidence that Galen believed any blood to pass from the right to the left ventricle otherwise than through the pores of the septum. As he says, however, that the branches of the "venous artery" (our pulmonary vein) "transmit thin and pure and vaporous blood in abundance" to the lungs for their nutrition,[145] we may infer that he held this supply to be derived from the left ventricle like that of the rest of the body. This was possible, according to Galen's system, because he held to the irrational opinion that what is now called the mitral valve closed less perfectly than the other valves, inasmuch as it possessed only two segments instead of three.

This supposed imperfection of the mitral valve played an important part in Galen's system, for it was possible thereby for the lung to receive, not only some spirituous blood from the left ventricle of the heart, but also, and especially, the injurious fumes which Galen held to arise from combustion in the left ventricle, to escape into the venous artery past the imperfect mitral valve, and to be exhaled in expiration. When this valvular door was open, therefore, the left ventricle drew from the lungs into itself crude spirits, these to be returned in some part perhaps to the lungs as spirituous blood in company with the deleterious fumes, when the valvular door was only ajar. This imperfection of the valve of two segments, however, was but a constant and fortunate exaggeration of a condition shared to a slight degree by all the valves; for Galen held these, in the act of closing, to allow slight regurgitation of spirits, vapor, or even of blood; and to do so exceptionally even when closed, if the movement of the heart were of unusual force. He commonly, however, assumed the tricuspid, pulmonary, and aortic valves to be competent, especially if he could gain a polemical point by doing so.[146]

More than thirteen centuries later Columbus, as we have learned, announced that blood from the right ventricle entered the left ventricle, not by pores of the septum, but exclusively by pores of the lungs, in passing through which latter it became spirituous blood, needing but little elaboration in the ventricle before entering the arteries for distribution to the body. Columbus denied and derided the passage of fumes from the left ventricle to the lungs, while he accepted the ancient doctrine of the cooling effect of respiration. His view of the meaning of the pulmonary transit is therefore a striking approximation to the truth—a closer one than that of Harvey, who questioned everything except the fumes given off in expiration, which fumes, of course, Harvey did not send along the Galenic path. As Columbus declared the spirituous blood to be made up in the lungs, and these, therefore, to need no supply thereof from the left ventricle; and as he also denied the passage of fumes through the venous artery; the flow through the latter became simplified, spirituous blood alone passing through it, and in the true direction from the lungs to the heart. Accordingly the mitral valve also was cured of its Galenic imperfection; to the latter Columbus does not even refer, but he simply describes all the four valves as competent.

Columbus, therefore, set forth the true course, and in no small degree the true nature and meaning, of the movement whereby blood passes from the right auriculo-ventricular ring to the aorta, and in so doing he expelled important errors from the Galenic system. But, strange to say, by thus purging it he greatly strengthened it, as was mentioned earlier in this paper, for he harmonized the fundamental doctrine of the Galenic system with the true mechanism and working of the cardiac valves, and with a rational theory of respiration.[147] This fundamental Galenic doctrine was the direct distribution of blood to the tissues through the veins from the liver as a center; no more than a fraction of the blood ever passing the tricuspid valve to reach the lungs or to enter the arteries as spirituous blood. Of this doctrine Columbus was not only an adherent, but a warm partisan against the Aristotelians; and, like Galen more than thirteen centuries before, Columbus points with emphasis to the tricuspid valve as evidence of the falsity of the Aristotelian doctrine that crude blood enters the heart to be perfected and returned thence to the vena cava for distribution.[148] The Galenic view that the liver is the origin of the veins and the source of the blood, by which word, unqualified, was meant the venous blood, was known even down to Harvey's day as the view of "the physicians," as opposed to that of "the philosophers," who contended in ingenious ways for the view of the great philosopher Aristotle that the heart is the origin of the veins and the source of the blood. Harvey in this contest repeatedly ranges himself in his writings with the Aristotelians and against the Galenists;[149] we shall see him bring the circulation into play to give very effective aid to the former against Galen himself.

Bearing in mind the Galenic meaning of the word "blood," and remembering that, in spite of the weak points in Galen's own armor, he possessed in the tricuspid valve a formidable weapon against the followers of Aristotle, listen to the following passage from Harvey's treatise of 1628. He says:—

"Whether or no the heart imparts anything more to the blood than transposition, locomotion, and distribution, whether it imparts heat also, or spirits, or perfection, must be looked into later and gathered from other observations. For the present be it enough to have shown sufficiently that during the beat of the heart the blood is transfused and withdrawn from the veins into the arteries through the ventricles of the heart, and is distributed to the body at large.

"This, to be sure, is conceded by all after a fashion, it being gathered from the structure of the heart and the arrangement, position, and use of the valves. But they seem to waver blindly as though in a dark place, and they put together varied, incoherent, and more or less contradictory doctrines and, indeed, set forth much upon conjecture, as has been shown already.

"There seems to me to have been one single principal cause of hesitation and error in this matter, viz.: the connection between the heart and the lung in man. The disappearance of the arterial vein in the lungs having been noted, and likewise that of the venous artery, great obscurity prevailed as to whence or how the right ventricle distributed the blood to the body, or the left ventricle drew blood from the vena cava. This is attested by the words of Galen when he inveighs against Erasistratus regarding the origin and use of the veins and the coction of the blood. 'You will answer,' Galen says, 'that the way of it is this: that the blood is prepared beforehand in the liver and is transferred thence to the heart to receive the rest of its proper character in complete perfection. Surely this does not seem devoid of reason; for no great and perfect work can be accomplished suddenly at one attempt and receive its entire polish from a single instrument. If then this be so, show us another vessel which leads the completely perfected blood forth from the heart, and distributes it to the whole body as the artery does the spirits.'[150] Behold Galen disapproving and putting aside a reasonable opinion because, besides not seeing the path of transit,[151] he cannot find a vessel to distribute the blood from the heart to the whole body!

"But had there been anyone on the spot to take the part of Erasistratus or of that opinion which is now our own and is confessed by Galen himself to be reasonable in other respects; and had the person aforesaid pointed his finger at the great artery [aorta] as the distributer of the blood from the heart to the body at large,—I wonder what answer that divine man would have made, full of genius and of learning as he was! Had he said that the artery distributed spirits and not blood, he certainly would sufficiently have refuted Erasistratus, who believed that only spirits were contained in the arteries; but in so doing Galen would have contradicted himself and would shamefully have denied what he sharply contends to be true in a special book[152] which he wrote against that same Erasistratus. For he proves by many powerful arguments, and demonstrates by experiments, that blood, and not spirits, is naturally contained in the arteries.

"But since the divine man concedes, as he often does in that same place, 'that all the arteries of the body arise from the great artery, and this from the heart; and that for a certainty blood is naturally contained and borne onward in all of them,' he maintaining 'that the three sigmoid valves placed at the orifice of the aorta forbid the return of blood into the heart, and that nature would never have set these valves in apposition to the most preëminent of the viscera were the valves not to do it some most important service;'—since, I say, the father of physicians concedes all this and in these very words, as he does in the book aforesaid, I do not see how he can deny that the great artery is the vessel adapted to distribute the blood, now arrived at complete perfection, from the heart to the body at large."[153]