HARVEY'S VIEWS ON THE USE OF
THE CIRCULATION OF THE BLOOD

COLUMBIA UNIVERSITY PRESS
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A portrait of William Harvey by Cornelius Jonson. This picture forms the frontispiece of Guilielmi Harveii Opera Omnia, London, 1766.

HARVEY'S VIEWS ON THE USE
OF THE CIRCULATION
OF THE BLOOD

BY
JOHN G. CURTIS, M.D., LL.D.
FORMERLY PROFESSOR OF PHYSIOLOGY IN COLUMBIA UNIVERSITY
IN THE CITY OF NEW YORK

Based on a Lecture Delivered in 1907, before the
Johns Hopkins Hospital Historical
Club at Baltimore

New York
COLUMBIA UNIVERSITY PRESS
1915
All rights reserved

Copyright, 1915,
By COLUMBIA UNIVERSITY PRESS.
Set up and electrotyped. Published December, 1915.

Norwood Press
J. S. Cushing Co.—Berwick & Smith Co.
Norwood, Mass., U.S.A.

PREFATORY NOTE

The writings of William Harvey, as published by him, and the letters published as part of his works, are all in Latin. The passages from Harvey's works which appear in English in the present paper are in part translations by the late Dr. Willis, with changes, sometimes considerable, by the present writer. In large part, however, the translations from Harvey are not even based upon Dr. Willis's work, but have been made by the present writer directly from the original Latin. Naturally he assumes responsibility for whatever he prints in English to represent Harvey's words; and to attempt, in print, a more minute discrimination between his own work as a translator and that of Dr. Willis would be tedious and unprofitable. Whoever may wish to make such discrimination may readily do so, however, as, in the present paper, a reference is made by page and line in the case of each translated passage, not only to the Latin text of Harvey's Opera Omnia, published by the Royal College of Physicians of London in 1766, but also to Willis's English translation thereof, published by the Sydenham Society in 1847, and entitled "The Works of William Harvey, M.D." Such references to the Sydenham Society's edition are indispensable for another purpose, viz.: in order that to each translated passage from Harvey in the present paper a context in English may readily be given by the reader.

It has seemed best that the various references to Harvey's Latin text should be made to that of the easily accessible Opera Omnia rather than to that of the rarer first editions of the several treatises. In the case of the passages quoted from the treatise De Motu Cordis et Sanguinis in Animalibus and from the treatise De Generatione Animalium, the Latin of the Opera Omnia has been collated by the present writer with that of the first editions. The first editions of the Exercises to Riolanus and of the various letters have not been accessible to him.

Much use has here been made of Harvey's private lecture notes, first published in 1886 by the Royal College of Physicians of London.

All the passages (except those from the Scriptures) quoted in the present paper from writers other than Harvey have been translated into English by the present writer directly from the original Greek text or the original Latin text, as the case may be.

JOHN G. CURTIS.

EDITORIAL NOTE

Professor Curtis, to whom I am indebted for much kindly help extended during a warm friendship of nearly thirty years, died September 20, 1913. One of his final requests was that his younger colleague arrange for the publication of the present paper, upon which its writer had been engaged for a period of several years and which happily was practically completed. This request, coming to me after the death of my friend, could be considered only as a command. It has, therefore, fallen to me to make a careful study of his text, to fill in with my own words occasional slight gaps, to make occasional verbal changes, to certify to the correctness of his numerous references, and to make the manuscript, written and in places rewritten many times with his own hand, ready for the press. This I have done with affection for his memory and with appreciation of his scholarly attainments. Dr. Curtis's work represents a more profound study of Harvey's ideas and comparison of them with those of the most important of Harvey's predecessors than has heretofore appeared. It is the work of one who from the background of the physiological science of to-day delighted in mastering the ideas of the fathers of modern physiology. If his work is to be summarized in a single sentence, it may be said that he has shown Harvey to be a disciple more of Aristotle than of Galen. Although Harvey had the courage and the originality to break away from him whose ideas had prevailed for fourteen centuries, and to find the truth in regard to the movement of the blood, he found much to approve in the master who had lived five hundred years before Galen. Harvey's true position in the world of physiological thought has not before been made known. Herein lies Professor Curtis's contribution to the history of his science.

FREDERIC S. LEE.

Columbia University,
June 1, 1915.

CONTENTS

ILLUSTRATIONS

HARVEY'S VIEWS ON THE USE OF THE CIRCULATION OF THE BLOOD

CHAPTER I

HARVEY'S ATTITUDE TOWARD THE QUESTION OF THE USE OF THE CIRCULATION

It is a happy moment for a physiologist when the train which is bearing him across the luxuriant plain of Venetia stops at the cry of "Padova!" If he have not informed himself too thoroughly about the sights which he will see at the Paduan University, he will enjoy his own surprise when he is ushered into the Anatomical Theater of Fabricius ab Aquapendente—a room in which standing-places rise steeply, tier above tier, entirely around a small central oval pit. Looking down into this, as he leans upon the rail, the traveler will realize with sudden pleasure that William Harvey, when a medical student, may often have leaned upon the self-same rail to see Fabricius demonstrate the anatomy of man. The place looks fit to have been a nursery of object-teachers, for it is too small to hold a pompous cathedra; and the veteran to whose Latin the young Englishman listened must have stood directly beside the dead body. To an American, musing there alone, the closing years of the sixteenth century, the last years of Queen Elizabeth of England, which seem so remote to him when at home, are but as yesterday.

Recent, indeed, in the history of medicine is the year 1602, when Harvey received his doctor's degree at Padua and returned to London; but for all that we are right in feeling that our day is far removed from his. The tireless progress of modern times has swept on at the charging pace; but in Harvey's time books were still a living force which had been written in days five and six times as far removed from the student of Padua as he from us. Galen, the Greek who practised medicine at imperial Rome in the second century of the Christian era; Aristotle, who had been the tutor of Alexander the Great five hundred years before Galen, when Rome was but a petty state warring with her Italian neighbors;—these ancients were still great working authorities in Harvey's day.[1]

It is against this persistent glow of the Greek thought that Harvey stands out so vividly as the first great modern figure in physiology. But it rather heightens than lowers his achievement that it was by the ancient glow that he saw his way forward, admiring the past, but not dazzled by it. In his old age he bade a young student "goe to the fountain head and read Aristotle, Cicero, Avicenna"; and in talk with the same youth Harvey called the moderns by a name so roughly contemptuous that it will not bear repeating.[2] Yet in his old age, in the very act of extolling the ancients, he wrote as follows:[3]—

"But while we acquiesce in their discoveries, and believe, such is our sloth, that nothing further can be found out, the lively acuteness of our genius languishes and we put out the torch which they have handed on to us."

The Anatomical Theatre at Padua, where William Harvey listened to the lectures of Fabricius ab Aquapendente.

It was in 1628, the year of his fiftieth birthday, that Harvey published, at Frankfort-on-the-Main, his famous Latin treatise entitled: "An Anatomical Exercise on the Motion of the Heart and Blood in Animals." A reader of to-day will be inclined to skim rapidly over the Introduction to this treatise and over much in the last three chapters; and probably he will take only a languid interest in the two brief Latin treatises which Harvey published in defense of the circulation, after more than twenty years of silence, in his seventy-first year, at Cambridge in 1649; these treatises being entitled: "Two Anatomical Exercises on the Circulation of the Blood, to Johannes Riolanus, Junior, of Paris."

The demonstration of the circulation in the treatise of 1628 is so irresistible that the ancient strongholds of belief crash to the ground at that summons like the walls of Jericho, and it seems a waste of time to scan the fragments. But for all that, the edifice which had stood for more than thirteen centuries was a goodly structure; and whoever shall have read Aristotle and Galen at first hand and shall then return to Harvey, will read with interest what the same reader treated as a mere foil for the great demonstration; and will realize that the irresistible quality of the latter is shared by Galen's demonstration that blood is naturally contained in the arteries.[4] Moreover, it will be seen that if the Greek of the second century could, like Harvey, appeal to observation and experiment, the English physician of the Renaissance, the student of Cambridge and Padua, was an apt pupil of the Greeks. Harvey could, and frequently and naturally did, view things from a Greek and ancient standpoint when proof of their nature was unattainable. This is to be seen not only in his earlier and later exercises on the circulation, but also in his last work, his "Exercise on the Generation of Animals" with appended essays, published in Latin at London in 1652, in Harvey's seventy-third year, two years after the appearance of the exercises addressed to Riolanus. This treatise On Generation deals also at various points with the blood and the circulation, as do in addition Harvey's published Latin letters. We shall find, too, the same leaning upon the ancients as immediate precursors in thinking, if we turn back from the publications of Harvey's old age to the very first written words of his which we possess, private lecture notes jotted down by him in his thirty-seventh year for use in 1616—notes happily printed and published in 1886.[1] In these notes, written more than eleven years before the publication of his most famous treatise, he sets forth for the first time, though briefly, the circulation of the blood, that physiological truth which to my mind is completely and indisputably Harvey's own discovery. It is with Harvey as the interpreter, not the maker, of this discovery, that I shall venture to deal in this paper.

In his old age the great discoverer recorded his own attitude, as an interpreter, in the following words:—

"That freedom which I freely concede to others, I demand with good right for myself also; liberty, that is, in dealing with obscure matters, to bring forward, to represent, the truth, that which seems probable, until the falsity thereof shall clearly be established."[5]

In 1636, eight years after he had published the treatise which now seems so convincing, Harvey was in Nuremberg and wrote to Caspar Hofmann, M.D., a professor of repute who lived there, offering to demonstrate the circulation to him. In his letter Harvey quotes impatient words of his German colleague, which show that in the face of proof the circulation still seemed to some men of high standing too useless to be true. Harvey says to Hofmann:—

"You have been pleased to reproach me rhetorically and chastise me tacitly as one who seems to you 'to accuse and condemn nature of folly as well as error, and to impose the character of a most stupid and lazy craftsman on her, since he would permit the blood to relapse into rawness and to return repeatedly to the heart to be concocted again; and, as often, to the body at large to become raw again; and would permit nature to ruin the made and perfected blood in order that she may have something to do.'"[6]

To this attack Harvey calmly rejoins as follows, speaking of the blood:—

"As to its concoction and the causes of this its motion and circulation, especially their final cause, I have said nothing, indeed have put the subject by entirely and deliberately; as you will find set down in plain words and otherwise if you will be pleased to read again chapters VIII and IX."[7]

More than twelve years later still, in defending the circulation against Riolanus, Harvey finds it necessary to say:—

"Those who repudiate the circulation because they see neither the efficient nor the final cause of it, and who exclaim 'Cui bono?'—(As to which I have brought forward nothing so far; it remains to be shown)—plainly ought to inquire as to its existence before inquiring why it exists; for from the facts which meet us in the circulation regarded as existing, its uses and objects are to be sought."[8]

In spite, however, of these disclaimers of formal position Harvey had repeatedly intimated, by the way, what was crossing his mind as to the meaning of the circulation, to set forth the proofs of which had been his main concern. Even in the eighth chapter to which Harvey appealed in support of his disclaimer Hofmann could have pointed to two passages as affording from his standpoint a basis for his attack. In the second and shorter of these two passages Harvey says of a vein as compared with an artery:—

"This is a way from the heart, that to the heart; that contains cruder blood, effete and rendered unfit for nutrition; this, concocted, perfect, alimentary blood."[9]

Harvey, indeed, as we shall find abundant evidence, was both an observer and a speculator. In the latter rôle he was not far removed from his physiological predecessors of two thousand years; as an observer it was his great merit to lead the physiologists of his time and to point out to those of all later centuries the path which they must follow.

CHAPTER II

THE CIRCULATION AND THE FEEDING OF THE TISSUES

That Harvey frequently took refuge in speculation need excite no surprise. In the seventeenth century, even with his extraordinary contributions of observed fact to the knowledge of the circulation of the blood, the paucity of physiological knowledge in general and of experimental methods was so great that at every turn a thinking man was tempted to fill in the gaps with that which was beyond his powers of ocular demonstration. Contemplation of the circulation, indeed, led Harvey into contemplation of widely diverse problems of the life process. The feeding of the tissues, the significance of respiration, the cause of the heart-beat, the relative importance of the heart and the blood in the bodily hierarchy, the bodily heat and its source, and the seat of the soul—to these and other topics he gave much attention, and these we must consider. Let us begin with the circulation and its relation to the feeding of the tissues.

In the chapter of Harvey's book which follows at once upon the brief qualitative statement quoted at the end of our last chapter, Harvey himself brings us face to face with the difficult quantitative question raised by his triumphant proof of the circulation. He says:—

"The blood under the influence of the arterial pulse enters and is impelled in a continuous, equable, and incessant stream into every part and member of the body, in much larger quantity than were sufficient for nutrition or than the whole mass of fluids could supply."[10]

Here we see that the rapid renewal of the blood in "every part and member of the body" presented itself to Harvey's own mind as calling for some other explanation than the simple feeding of the tissues. The question of "cui bono" which his discovery raised is still but incompletely answered; in Harvey's day it was almost unanswerable. In dealing from time to time with its main features he himself, as we shall see, could only bring forward inadequate observations and shift his ground from one erroneous doctrine to another. In justice to his opponents, who seem to us so unreasonable, let us remember how prodigious this new question of "cui bono" must have seemed when the circulation itself was a novelty. Let us remember also that for nearly two thousand years the tissues had been held to feed themselves tranquilly out of the contents of the vessels in a way fitly expressed by the old simile of irrigation ditches in a garden—a simile which Aristotle and Galen had borrowed in turn from Plato.[11]

But if Harvey saw only too well that the feeding of the tissues could not explain the circulation, he had at least seen plainly how the doctrine of the circulation clarified the ancient but current doctrine as to the absorption of the digested food. The portal vein had been accepted as the route of this absorption. No doubt both Aristotle and Galen had seen its ruddy contents; at any rate both had concluded that the chyle was changed within the portal vein into a crude approximation to blood.[12] That the same vessel should carry to the liver altered chyle, and from the liver blood to nourish the stomach and intestines, had involved a difficulty which Galen had met with characteristic cleverness. He had cited in support of such a reversal of flow the flow of the bile into the gall-bladder and out by the same duct, the movement of food and vomit into and out of the stomach by the œsophagus, and the relation of the os uteri to impregnation and parturition.[13] Harvey says:—

"For the blood entering the mesentery by the cœliac artery and the superior and inferior mesenteries proceeds to the intestines, from which along with the chyle that has been attracted into the veins it returns by their numerous ramifications into the vena portæ of the liver, and from this into the vena cava, and this in such wise that the blood in these veins has the same colour and consistency as in other veins, in opposition to what many believe to be the fact. Nor need we hold the improbable belief that two inconveniently opposed movements take place in the whole capillary ramification, namely, movement of the chyle upward, of the blood downward. Is not the thing rather arranged as it is by the consummate providence of nature? For were the chyle mingled with the blood, the crude with the concocted in equal proportions, the result would not be concoction, transmutation, and sanguification, but rather, because they are reciprocally active and passive, a mixture, their union with one another producing something intermediate, precisely as when wine is mixed with water and [in] vinegar and water [oxicratum]. But when a minute quantity of chyle is mingled with a large quantity of blood flowing by, a quantity of chyle that bears no notable proportion to the blood, the effect is the same, as Aristotle says, as when a drop of water is added to a cask of wine, or the contrary; the resulting total is not a mixture, but is either wine or water. So in the dissected mesenteric veins we do not find chyme or chyle and blood, separate or mingled, but only blood, sensibly the same in color and consistency as in the rest of the veins."[14]

In a second passage of the same chapter,[15] Harvey returns to this subject; and again, twenty-one years later, in his first exercise to Riolanus, as follows:—

"Our learned author mentions a certain tract of his on the Circulation of the Blood: I wish I could obtain a sight of it; perhaps I might retract. But had the learned writer been so disposed, I do not see but that, having admitted the circular motion of the blood (and in the veins, as he says in the eighth chapter of the third book,[16] the blood incessantly and naturally ascends, or flows back, to the heart, as in all the arteries it descends or departs from the heart), all the difficulties which were formerly felt in connection with the distribution of chyle and the blood by the same channels are brought to an equally satisfactory solution; for all the mooted difficulties vanish when we cease to suppose two contrary motions at once in the same vessels, and admit but one and the same continuous motion in the mesenteric vessels from the intestines to the liver."[17]

From this passage we see, in passing, that Harvey at the age of seventy made little account of Caspar Aselli's discovery of the lacteals, published twenty-two years before in 1627,[18] the year before the announcement of the discovery of the circulation. Harvey's mind was focused on the blood, its motion and its meaning; this was to him the subject of prime importance. The ancient doctrine of the feeding of the tissues provided an insufficient reason for the existence of what his observations and his experiments revealed to him.

CHAPTER III

RESPIRATION AND THE CIRCULATION

So the feeding of the tissues could not sufficiently account, to Harvey's mind, for the swiftness of the circulation. What could? It is easy for us to recite the multitudinous modern duties of the blood as a bearer of cells and of chemicals from point to point and as a protector against poisoning; above all it is easy to exclaim "respiration";—to read the most striking part of the riddle by knowing the answer which was wrung laboriously from Nature after Harvey had died. It is easy for us to see that speedy death from loss of the circulating blood is practically the same as death from ligature of the arteries of the brain, or from drowning, or strangulation, or a broken neck. But this was veiled from him, and what best accounts for the volume and swiftness of the Harveian circulation was, in Harvey's day, a stumbling block to its acceptance; for no adequate reason was apparent why the whole mass of the blood should traverse the lungs, or why, if the veins receive their blood from the arteries, the venous blood should differ in color from the arterial.

Let us remember that throughout Harvey's life air was still an elementary body in the eyes of many and, for all, blood was a quite mysterious, ruddy, hot, vital liquid. Only weak magnifying glasses were available for him, and the powerful lenses of Malpighi and van Leeuwenhoek had not yet revealed to the world either capillary or blood-corpuscle. Moreover, the gossiping John Aubrey, the man who had been advised about his youthful studies by Harvey, wrote of him some years after his death, that "he did not care for Chymistrey, and was wont to speake against them [the chemists] with an undervalue."[19] Where would physiology be to-day, had not histology and chemistry long stood in the forefront beside her?

In a passage of the treatise of 1628 Harvey speaks of respiration, as follows:—

"And now it has come to this, that it would seem better worth while and more straightforward for those who seek the path by which in man the blood passes through the vena cava into the left ventricle and the venous artery,[20] to be willing to search for the truth by dissecting animals, in order to look for the reason why in the larger and more perfect animals, when full grown, nature chooses to make the blood percolate through the parenchyma of the lungs rather than take wide open paths as in all other animals (it being understood that no other path and transit can be thought out):—whether it is because the larger and more perfect animals are hotter and when they are full grown their heat is more ignited, so to speak, and prone to be smothered, that there is this permeation and transfer through the lungs in order that the heat may be tempered by the inspired air and guarded from boiling up and smothering—or for some other similar reason. But to determine these matters and explain them completely were to enter on a speculation as to the purpose for which the lungs are made. About these and their use and motion, and the whole subject of ventilation and the need and use of air, and other matters of this sort, and about the various different organs created in animals by reason thereof, although I have made a vast number of observations, I shall not speak till I can more conveniently set them forth in a treatise apart, lest by wandering at this point too far from my subject, which is the motion and use of the heart, I should seem to deal with something else and leave my position, to confuse and evade the question."[21]

Farther on in the same treatise Harvey says:—

"Moreover, the reason why the lungs have vessels so ample, both vein and artery, that the trunk of the venous artery exceeds in size the crural and jugular branches taken both together; and the reason why the lungs are so full of blood as we know them to be by experience and inspection (heeding Aristotle's warning,[22] and not deceived by the inspection of such lungs as we have removed from dissected animals from which all the blood had flowed out)—the reason is, that in the lungs and heart is the storehouse, the source, the treasury of the blood, the workshop of its perfection."[23]

So the great Englishman gropes for a moment or two by the light of ancient Greek doctrines and puts the question of respiration by. But this very attitude shows Harvey's thought to be in such contrast with the thought of to-day that in order to understand him we need to learn more fully his views of respiration; and we find with satisfaction that in his lecture notes of more than eleven years before he had not put this question by, for he had been called upon to lecture upon the uses of the lungs. We must seek in his lecture notes, therefore, for what he had thought those uses to be. These notes, however, we shall be unable to follow unless now, first of all, we shall give the floor for a while to the ancients; for from their doctrines Harvey necessarily took his cue, like the other thinkers of his time.

The momentous physiological facts that the living body of man, beast, or bird, is warm of itself and that its cooling means its death, must always have struck and impressed the human mind, whether trained or untrained. More than nineteen centuries before Harvey certain thoughts of Aristotle were recorded as follows:—

"In animals all the parts and the entire body possess a certain innate natural heat; wherefore they are sensibly warm when living, the reverse when making an end and parting with life. In the animals which have blood the origin of this heat is necessarily in the heart, in the bloodless kinds in the analogue thereof; for all work up and concoct the nourishment by means of the natural heat, the master part most of all. Life persists, therefore, when the other parts are chilled; but if what resides in this one be so affected total destruction ensues, because upon this part they all depend as the source of their heat, the soul being as it were afire within this part; that is, within the heart in the animals which have blood, in the bloodless kinds in the analogue thereof. Necessarily, therefore, the existence of life is coupled with the preservation of the heat aforesaid, and what is called death is the destruction thereof."[24]

This heat which is innate in all living animals was styled by Aristotle not only "innate" but "natural," "vital,"[25] and "physical,"[26] it being indispensable to life and to the working of the soul. He held the continued existence of the innate heat to depend upon conditions similar to those under which a fire is kept alive, viz.: protection both from burning out and from extinction due to external forces. Yet the true nature of combustion was not settled till more than a century after Harvey's death. The fact that air is necessary to fire must always have been a matter of common knowledge. Therefore, the views of the relations of air to fire maintained by Aristotle nearly twenty-one centuries before the discovery of oxygen did not seem naïve to Harvey, whatever they may seem to us. Aristotle held that air exerts upon fire a cooling influence which saves it from burning out too fast; and that the same influence is exerted upon the vital innate heat of animals by the air which they breathe in, or the water which bathes their gills.[27] Moreover, Aristotle says:—

"Why those animals breathe most which have lungs containing blood, is plain from this: that the warmer an animal is, the greater need it has of cooling, while at the same time the breath passes easily toward the source of warmth within the heart. But the way in which the heart is pierced through toward the lung must be studied from dissections and from the history of animals which I have written. In general terms, then, it is the nature of animals to need cooling on account of the firing of the soul within the heart."[28]

In the treatise styled the "History of Animals," to which he refers us, Aristotle says:—

"There are also channels from the heart which lead into the lung and divide in the same way as the windpipe, and they accompany the channels from the windpipe throughout the entire lung. The channels from the heart lie uppermost; but no common channel exists, for it is by contact[29] that they receive the breath and transmit it to the heart."[30]

The collection of ancient Greek commonly called the "Works of Hippocrates" is judged to be of the fifth and fourth centuries B.C. There is included in this collection a brief treatise on the heart; and in this occurs the earliest known account of the structure and use of the semilunar valves, which together with the rest of the cardiac valves were unknown to Aristotle. In the same Hippocratic treatise the doctrine is adhered to of the entrance of air into the heart for cooling purposes, both the right and the left ventricle being specified as receiving it. The author says:—

"The vessel which leads out of the right ventricle ... closes toward the heart, but closes imperfectly, in order that air may enter, though not very much."[31]

This piece of incorrect physiology may well have received support from the fact that the pulmonary semilunar valve is commonly found to be not quite competent when the dead and dissected pulmonary artery of the bullock is distended with water—an observation which the ancient author intimates that he has made,[32] though he does not specify the creature dissected.

Nearly five hundred years after the death of Aristotle, the analogy between life and flame was discussed, formally and at some length, by Galen. He knew his Aristotle well, and agreed with him as to the importance of respiratory cooling for protracting the indispensable heat of animals.[33] But we find Galen dealing with the uses of respiration in a less simple way than Aristotle. In a polemical treatise Galen debates the question whether "the breath drawn in in respiration" actually enters the heart, or whether it cools it without entering it. He says:—

"It is possible that the whole is breathed out again, as was believed by most physicians and philosophers, and those the keenest, who say that the heart, while it craves to be cooled, is in need not of the substance, but of the quality[34] of the breath, and that the use of respiration is indicated by the part.... I have shown in my treatise on the use of respiration that either an absolutely minute quantity, or none at all, of the substance of the air, is taken into the heart."[35]

It is clear, however, that Galen, when delivering himself of the foregoing, was a trifle carried away by the ardor of contention; for in the very treatise to which he refers us, as well as elsewhere, he not only dilates upon the cooling effects of breathing, but admits the entrance of air into the heart for a definite physiological purpose. This purpose, however, which we shall study later, is not cooling and is counted of secondary importance by Galen. Nevertheless, he goes so far as to say this:—

"That some portion of the air is drawn into the heart in its diastole and fills the vacuum which is produced, is sufficiently shown by the very magnitude of the dilation."[36]

In his treatise "On the Use of the Parts of the Human Body" Galen takes a more judicial tone in the following brief, calm summary:—

"The use of the respiration of animals arises from the heart, as has been shown. The heart itself needs in some sort the substance of the air; but, first and foremost, it craves to be cooled, because it boils with heat. The heart is cooled by the cool quality of inspiration; but expiration also cools, by pouring out that which seethes within the heart and is, in a way, burned up and sooty."[37]

Thus do we see the modern products of respiration foreshadowed.

Galen believed that the heat of animals is safeguarded also by the entrance of cooling air through the pores of the skin into the arterial system, and by the exit through these pores of injurious fumes out of the arteries.[38] In the introduction to Harvey's great treatise of 1628[39] the English physician riddles with adverse arguments this doctrine of Galen; to this we shall return later, as we shall to Galen's belief that the brain draws cooling air directly into its ventricles out of the nares through the cribriform plate of the ethmoid bone.[40]

In passing from Aristotle to Galen we have crossed nearly five centuries. Now let us pass at a leap across fourteen centuries more, from Galen at imperial Rome under Septimius Severus to Harvey at London under King James the First. Having briefly scanned the doctrines of the Greeks, let us take up our study of respiration in Harvey's private lecture notes of 1616. His crabbed handwriting has been deciphered by experts, and his notes have been both photographed and printed. If we seek therein for his thoughts about respiration, and track them through the jungle of abbreviated careless Latin and racy English in which they were jotted down, we shall find them Galenic in part, but also denying a truth which Galen had accepted. Harvey's notes are often too disconnected for quotation, calling rather for paraphrase or summary; and to make either is a task which one cannot approach without diffidence, especially as this task involves translation also. Of what I have ventured to prepare to represent parts of Harvey's note-book in the present paper some passages are simple translations, such English words as Harvey interspersed being transcribed. Naturally such passages are included between quotation marks. These are not used, however, in the case of a paraphrase or summary, even if it contains scattered English words which are Harvey's own.

Harvey fully shared the ancient view of the supreme importance of the heat of animals. In his note-book he, like Galen, deals with respiration under the heads: first, of a possible absorption of some of the substance of the air; and, second, of cooling and ventilation. Let us first take up the second head. Harvey says:—

"Without nourishment life cannot be, nor nourishment without concoction, nor concoction without heat, nor heat without ventilation;" for heat perishes either of wasting or of smothering; "so there is cooling and ventilation of the native heat, ventilation especially."[41]

His words contain reminders of Aristotle;[24] and he continues about respiration in a vein as ancient as Hippocrates,[42] as follows:—

"Nothing is so necessary, neither sense nor food. Life and respiration are convertible terms, for there is no life without breathing and no breathing without life. If the eye be cut out there is an end of seeing; if the legs be cut off there is an end of walking; if the tongue, of speech, et cetera; if respiration, there is an end of everything immediately."[43]

When Harvey jotted this down he had in mind a Galenic passage which doubtless had become the common property of all physicians in his day; for the removal of eye and legs figures in the first chapter of Galen "On the Use of Respiration."[44] Harvey continues:—

"Hence large animals are much warmer and breathe frequently, because they have need of greater cooling and ventilation inasmuch as they very greatly abound in blood and heat."[45]

In the margin opposite this passage there is written:—

"Why and how air is needed by animals which breathe and also air is necessary to a candle and to fire see W. H."

We may conjecture that this note refers to Harvey's promised treatise on respiration, which was never published.

So far Harvey has simply reiterated the ancient doctrine of cooling and ventilation, as in the passages quoted previously from the treatise of 1628. We shall find it very interesting to see how he deals with the other ancient doctrine that some of the substance of the air joins the blood in respiration. That this is true, gas analysis and the mercurial air-pump have taught us; but in this matter modern demonstration does but confirm, extend, and make precise one of the oldest of physiological beliefs. Regarding this we must now give the floor once again to the ancients, in order to make Harvey comprehensible.

Even in the days of Empedocles and Hippocrates, in the fifth and fourth centuries before Christ, men wrote of something derived from the outer air being present, for the use of the organism, in the vessels which also contain the blood.[46] To express this derivative of the outer air the ancient Greeks employed the word "pneuma" (πνεῦμα), the fundamental meaning of which seems to have been "air in motion." Various meanings were acquired by "pneuma," such as the breath of living things, the wind, or simply the air, or what we mean by the words "gas," "vapor," "steam," "exhalation," "emanation." The Latin word equivalent to "pneuma" is "spiritus," and so the English derivative of this, the word "spirits," came into use to express various meanings of the Greek "pneuma." A Hippocratic writer tells us that "the spirits cannot stand still, but go up and down" in the blood vessels. The word "spirits" here designates a derivative of the outer air crudely mingled with the blood.[47] To this writer the distinction between veins and arteries was unknown.

In the genuine works of Aristotle this Hippocratic doctrine does not reappear, though it is fairly certain that Hippocratic treatises which contain it were written before Aristotle's time. We have seen that the entrance of air into the heart, to cool the same, is an important feature of the Aristotelian physiology. Beyond the Aristotelian heart, however, we cannot trace the air which enters it. Yet we find "pneuma," "spirits," referred to by Aristotle, not seldom obscurely or in very general terms, as doing service, sometimes momentous service, in the physiology of generation and in certain workings within the bodies of full-grown creatures. In disease also spirits may play a very important part. These Aristotelian spirits, however, when their origin can be traced at all, are either innate or appear to be vapor produced within the body itself by heat or by disease. They do not appear to be recruited from the outer air which has penetrated the lungs and heart, that air seeming to complete its function within the lungs or within the heart itself by sustaining the native heat which is the great instrument of the soul, and in which the very soul itself is fired.[48]

Physicians of Aristotle's time, however, revived and handed on the doctrine that not only blood but a derivative of the air is distributed to the body at large through the vessels. After the distinction between veins and arteries had been clearly made and the latter had received their present name, a striking modification of this doctrine of the spirits was adopted and pressed by the Greek physician Erasistratus, about 300 B.C., not many years after the death of Aristotle. This modified doctrine separated the paths taken within the vessels by the blood and the spirits derived from the air, and declared the transmission of the necessary blood to the body at large to be by the veins only, that of the necessary spirits, styled "vital," to be by the arteries only. More than four hundred and fifty years later Galen shattered this doctrine and incorporated the vital spirits in the arteries with the blood, which he proved by epoch-making experiments to be normally present in the arteries, he, however, clearly recognizing differences between the cruder blood in the veins and the spirituous blood in the arteries. The tissues, therefore, still received vital spirits by way of the arteries, according to Galen, but not spirits in their pure gaseous Erasistratean state.[49] Now let Galen tell us more in his own words:—

"The breath from the windpipes, which had been drawn in from without, is worked up in the flesh of the lungs in the first place; in the second place in the heart and arteries, and especially in those of the net-like plexus; and to perfection in the ventricles of the brain, where the spirits become completely animal. But what the use may be of these animal spirits and why we have the temerity to call them so, when we confess that we are still utterly ignorant as to the substance of the anima [i.e., of the soul], this is not the moment to say."[50]

The complex physiology of this passage is so obsolete that its very phraseology is meaningless without a commentary. In the first place, what are the animal spirits? This expression, once a technical term of physiology, survives only in colloquial English, and even there merely as a label of which the origin is known to few. In this phrase the adjective "animal" does not refer to lower creatures as opposed to man, but is used in its obsolete original sense of "pertaining to the soul," for which latter the Latin word is "anima," the Greek word "psyche" (πσυχή). "Psychical spirits" would best translate into the English of to-day either the original Greek expression "pneuma psychikon" (πνεῦμα ψυχικόν) or its Latin equivalent "spiritus animalis." But the expression "animal spirits" was for too long a time an English technical term to be superseded now. These animal spirits, that is, spirits of the soul, were not peculiar to man, but were possessed by lower creatures also; for neither the Latin word "anima" nor the Greek word "psyche" implied immortality, as the English word "soul" is now so commonly understood to do. Plato formally recognized a mortal and an immortal part of the human psyche;[51] and Aristotle admitted the existence in animals lower than man of the lower grades of psyche, and conceded the lowest grade even to plants.[52] The perfected animal spirits were of the very highest physiological importance, as their name implies, they being for Galen no less than "the first instrument of the soul,"[53] and thus assuming the lofty rank given by Aristotle to the native heat. For Galen the animal spirits were the medium of sensation and volition and were imparted by the ventricles of the brain to the spinal cord and nerves, the fibers of which were believed, accordingly, to consist of tubes in which the subtile animal spirits were contained, the bore of these tubes being too small to be visible.

We can now follow the quoted Galenic passage and trace the full significance of that entrance of the substance of the air into the heart which Galen repeatedly acknowledged, though sometimes grudgingly. According to Galen whatever air was taken into the heart had first been "concocted" in "the flesh of the lungs." Next, this aërial substance had been worked up in the heart with the vapor of the blood into vital spirits, and these became incorporated with the finer blood destined for the arteries. Moreover, as each arterial diastole was due to an active expansion of the arterial wall, at each diastole there became blended with the contents of the arteries still more of the substance of the air, which was sucked into the arterial skin through the countless pores of the bodily skin, these being too fine to permit bleeding. The vital spirits, thus formed and modified, were blended with the blood of the arteries and supplied to the body at large. A part of these vital spirits mounted with the blood into the carotid arteries. In the swine and the ruminants, notably in the calf, the branch given to the brain by each carotid artery breaks up at the base of the skull within the cranial cavity into numerous fine twigs, which form collectively a net-work, styled in the passage from Galen already quoted the "net-like plexus." This plexus is called by modern anatomists the rete mirabile. It was falsely assumed by Galen to exist in man. The plexuses of the two sides anastomose freely across the median line, and through them passes the entire blood supply of the brain; in the animals which possess them these plexuses seem the terminal branches of the vertebral arteries also. The small vessels of each net-like plexus reunite, and thus reconstitute the artery of the brain before this artery has pierced the dura mater. Galen regarded the net-like plexus as an organ of much importance intercalated in the course of the artery for the still further elaboration of the vital spirits, which, thus altered, were exhaled from the cerebral arteries into the cerebral ventricles.[54] In these ventricles the spirits attained their final perfection, becoming "completely animal," by the aid of still more of the substance of the air, which the diastole of the pulsating brain had drawn into its cavities directly from the nares through the numerous holes in the ethmoid bones. It is a striking fact in this connection that in some of the domestic animals on each side of the head the cavity of the nares is separated from the ventricular cavity of the brain by an exceedingly thin, though complex, partition: as may be seen on dissection, if the nares and the brain in situ be opened at the same time.

Now let Galen speak again as follows:—

"I have clearly shown that the brain is, in a way, the source of the animal spirits, watered and fed by inspiration and by the abundance supplied from the net-like plexus. The proof was not so clear as to the vital spirits, but we may deem it not at all unlikely that they exist, contained in the heart and arteries, they, too, fed by respiration mainly, but to some degree by the blood also. If there be such a thing as the natural spirits, these would be found contained in the liver and veins."[55]

The animal spirits were sustained, as we have seen, by three kinds of respiration which might be called pulmonary, cutaneous and cerebral. We may perhaps conjecture that it was largely Galen's acceptance of the two latter, the last especially, which enabled him sometimes to treat as doubtful the entrance into the heart of that air from which the vital spirits were held to be derived. Of the natural spirits he evidently made small account.[56]

A modern physiologist, musing upon all this, might see in the vital spirits a dim foreshadowing of oxyhæmoglobin; might see in the operation of the animal spirits a plainer foreshadowing of the nerve impulse of to-day.

Some account, such as the foregoing, of the very complex ancient doctrine of the spirits is indispensable for the study of Harvey; for that doctrine, more or less modified, was still the accepted medical doctrine of his time. After this renewed study of the ancients let us now return again to Harvey's note-book at the place where he takes up the question of the action of the lungs upon the blood otherwise than by the cooling and ventilation of the innate heat. It is necessary in his opinion that a further concoction of the blood into spirituous arterial blood should be accomplished by the fleshy parenchyma of the lungs in animals which require a warmer, thinner, "sprightly kind of aliment," as his own English styles it.[57] The probability of such a concoction is shown by the separation of excreta which indicate it, such as sputa, at the lung.[58] On the other hand, in such creatures as frogs and turtles the lungs are fleshless, spongy, and vesicular, and give no sign of blood or excreta. Hence we may infer that the pulmonary concoction of the blood, though it probably occurs, is limited to such animals as possess fleshy and sanguinolent lungs. Hence, again, it follows that the concoction aforesaid is a function of secondary importance, because it is not universal; and that the foremost function of the lungs is their motion, the windpipes constituting their most important part, rather than the parenchyma.[59] Two functions of the lungs, says Harvey, are affirmed by the medical authorities: first, the cooling and tempering of the blood; second, the preparation of natural spirits and air to be made into vital spirits in the heart. From all this there result the excreta of pulmonary concoction, which are something between water and air, and the fumes which are breathed out in expiration continually and incessantly. Harvey observes correctly that Realdus Columbus had declared himself to have discovered the continual motion of the lung to be the means whereby the spirits are prepared; the blood being thinned by the agitation, thoroughly mixed with air, beaten, and prepared.[60] Harvey also cites Galen as saying that the parenchyma of the lung concocts spirits out of air as the flesh of the liver concocts the blood.[61] On turning to the Galenic passage cited by Harvey one finds that it is out of the food that the blood is thus concocted by the liver.

Realdus Columbus, to whom Harvey refers, was the Italian anatomist who in 1559, fifty-seven years before the Harveian circulation was verbally announced, gave to the world the important truth that such blood as the right ventricle imparts to the left reaches the latter by traversing the pores of the texture of the lungs,[62] instead of the pores of the septum of the ventricles, as Galen had taught. The existence of these pores of the septum Vesalius had pointedly wondered at in 1543 and had emphatically doubted in 1555.[63] Four years later his former assistant and temporary successor, Columbus, flatly denied the existence of the pores. It was natural, therefore, that in the same book in which Columbus brought forward the path through the lungs to replace that through the septum he should declare that the vital spirits are made out of air worked up with the blood in the lungs and then merely perfected in the left ventricle. This doctrine was an important advance beyond what Galen had taught, viz.: that the spirits are but slightly prepared in the lungs out of air and then sent to the left ventricle to undergo their main preparation and to be worked up therein with the blood which had filtered into it directly out of the right ventricle.

So much for the views of the medical authorities. We have found Harvey agreeing with them that the ancient doctrine of the cooling and ventilation of the native heat by respiration is sound. We have found him acknowledging that in some animals some sort of concoction also of the blood destined for the arteries may be brought about by the pulmonary parenchyma as a function of secondary importance. But now we shall find him rejecting the second accepted doctrine of the physicians, viz.: that some of the substance of the air is taken into the pulmonary vessels and enters the blood. This conjecture had had believers for two thousand years, and was destined to be proved true triumphantly after Harvey's death. In rejecting it he threw away a precious clue to the meaning of his own great discovery.

"It is more philosophical," he says, "not to share the common belief that the spirits are distinct and separate from the humors and parts because the spirits are produced in diverse places or contained in diverse things," but to hold that the spirits and the blood are one thing, like the cream and watery part (serum) in milk or, to borrow a simile from Aristotle's reasonings about the blood,[64] like heat and water in hot water, or like flame and a vapor which feeds it (nidor). As light is to a candle, so are the spirits to the blood.[65]

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]

Page 80, right, of William Harvey's Prelectiones Anatomiæ Universalis, or Lecture Notes of 1616. The passage contains the first recorded mention of the movement of the blood in a circle.

WH constat per fabricam cordis sanguinem
per pulmones in Aortam perpetuo
transferri, as by two clacks of a
water bellows to rayse water
constat per ligaturam transitum sanguinis
ab arterijs ad venas
vnde Δ perpetuum sanguinis motum
in circulo fieri pulsu cordis
An? hoc gratia Nutritionis
an magis Conservationis sanguinis
et Membrorum per Infusionem calidam
vicissimque sanguis Calefaciens
membra frigifactum a Corde
Calefit

Transcript of the preceding page.

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]

Thus does the great English discoverer bring the pulmonary transit and the circulation of the blood to the rescue of the Aristotelian heart, despite Galen and the tricuspid valve! Between Harvey and the school that refused to the heart more than a fraction of the blood, there could be no peace. It is the Galenists whose system he attacked and shattered so thoroughly; and those who long and bitterly opposed the acceptance of the Harveian circulation were of the Galenic school. In a private letter written twenty-three years after the publication of his discovery, Harvey excuses the French physician Riolanus for having slighted the circulation not long before, saying, among other things:—

"It was proper that the dean of the College of Paris should keep the medicine of Galen in repair; and should admit no novelties into his school without the utmost winnowing."[154]

CHAPTER VI

THE CIRCULATION AND THE PRIMACY OF THE BLOOD

We have found the discoverer of the circulation an admirer and defender of Aristotle; but we shall leave him far less Aristotelian than we found him. Before he died, he had transferred to the blood itself that physiological primacy which Aristotle had given to the heart; Harvey having come to regard the blood even as the very seat of the soul, harking back to a Greek doctrine older than Aristotle and expressly discountenanced by him.[155] This final view of Harvey was not simply an outcome of his old age, though he develops and formally declares and insists upon the doctrine of the primacy of the blood in the writings which he published when beyond the age of seventy, more than twenty years after the publication of his treatise of 1628. We have seen that in this his most famous work he adheres impressively to the Aristotelian doctrine of the primacy of the heart; though even this work contains utterances of Harvey which do not well accord with that doctrine. More than eleven years earlier, when making notes for his lectures of 1616, he asked himself in striking terms, whether the circulation do not exist in order that the blood may be heated by the heart.[156] Yet there are passages in those very same notes which show that, beside vaguer conjectures,[157] the doctrine of the primacy of the blood was present clearly to Harvey's mind even so early as in his thirty-seventh year. In his lecture notes four passages are especially significant as to this doctrine. Of these the first is as follows:—

"Yf I could shew what I hav seene, y^t weare att an end between physicians et philosophers."

After these words in English Harvey falls into his usual Latin, which may be translated thus:—

"For the blood is rather the author of the viscera than they of it, because the blood is present before the viscera, nor yet coming from the mother,[158] for in the egg there is a drop. The soul[159] is in the blood."[160]

In a second passage of his note-book Harvey says, speaking of the heart:—

"It is most exceeding full of contained blood, as no other viscus is. Wherefore Aristotle [holds] against the physicians that the origin of the blood is not in the liver but in the heart, because in the liver there is no blood outside the veins. Rather is the blood the origin of both, as I have seen."[161]

In a third passage Harvey says of the heart that its

"temperature is exceeding hot, inasmuch as it is exceeding full of blood."[162]

In a fourth passage of the lecture notes which bears upon the primacy of the blood we may read:—

"1. [The heart] is the most principal part of all, not because of itself,[163] for its flesh is more fibrous and harder and colder than the liver, but because of the abundance of blood and spirits in the ventricles.

"1. Whence the fount of the entire heat.

---

"Whence the auricles pulsate, after removal of the heart, because of the multitudinous blood.[164]

"2. Nor is [the heart] the principal part because of its origin: for I believe that the ventricles (which in the fœtus are both united as in fishes) are made out of a drop of blood which is in the egg; and that the heart, together with the rest [of the parts] all sprout[165] simultaneously, as [occurs] in an ear of corn, from an imperceptible size. Is there only a drop of blood in the auricles whence bestowing heat upon all parts, receiving from none, it is the citadel and domicile of the heat, the household shrine[166] of that edifice, fowntayn conduit hed."[167]

More than eleven years after the making of his lecture notes Harvey, at the age of fifty, published his treatise of 1628; and later, after keeping silence for more than twenty years, he published together the two Exercises addressed to Riolanus. During these twenty years and more the blood must have been rising and the heart declining, in Harvey's esteem, as ruling powers in the body; for at the end of that time more than thirty-two years after the jotting down of the statements and varied conjectures of his lecture notes, he formally throws over Aristotle's primacy of the heart, in a passage near the close of the second Exercise to Riolanus. Of this passage the following is a part. Referring to certain opinions, mainly Aristotelian, regarding the heart and blood, Harvey says:—

"To speak openly, I do not believe that those things are so in the sense commonly received; and my opinion is inclined in the direction aforesaid by much which is visible in the generation of the parts, but which is not convenient to set down here. Soon, perhaps, I shall make public things even more wonderful and destined to cast even greater light upon natural philosophy.

"For the present I will only say and set forth without demonstration—by good leave of the learned and with due respect to the ancients—that the heart, as the beginning, author, source, and origin of everything in the body and the first cause of life, should be held to include the veins and all the arteries and also the contained blood; just as the brain, including all its nerves and sensory organs and spinal marrow, is the one adequate organ of sensation, as the phrase is. If by the word 'heart,' however, only the body of the heart be meant with its ventricles and auricles, I do not believe that it is the manufacturer of the blood; nor that the blood possesses vigor, faculty, reason,[168] motion, or heat, as the gift of the heart."[169]

In the second year after that of the Exercises to Riolanus Harvey's final publication, his treatise On Generation with appended essays, was given to the world, not long before his seventy-third birthday. During how many years this work had been in preparation we do not know; but it is avowedly based upon the views of Aristotle, whom Harvey styles his "dux"—his leader—as regards the subject of this treatise.[170] In it, to be sure, the ancient master is often weighed in the balance and found wanting by Harvey, who even questions whether Aristotle had seen for himself what he "narrates as to the generation of the chick," or "had accepted it from some expert."[171] Nevertheless, it is with the doctrines of Aristotle that Harvey incessantly compares the results of observation. Here the veteran records anew his denial of the Aristotelian primacy of the heart, and records as well his final emphatic assertion of the primacy of the blood. In regard to these matters it is interesting to note the various grades of expression which appear to mirror in this single work the various phases of Harvey's thought.

In the following florid passage doubt of the primacy of the heart seems hardly even hinted at. Harvey says:—

"Certain of the parts themselves are said to be generative, such as the heart, from which Aristotle declares that the rest of the parts derive their origin; as is also clear from the history which I have given. The heart, I say—or at least its first beginning, to wit, the vesicle and leaping point—constructs the rest of the body to be its future abode; enters this when once built up, and hides in it, vivifies and governs it; fortifies it with ribs and sternum super-imposed as a bulwark; and is a kind of household shrine, as it were, the first seat of the soul, the first receptacle and perennial soul-endowed[172] hearth of the innate heat, the source and origin of all the faculties, and their sole relief in calamity."[173]

Divergence from Aristotle in the matter of the heart is plainly marked, however, in the following passage of the same treatise, where Harvey says:—

"We find the blood formed before anything else in the egg and in the product of conception;[174] and almost at the same time the receptacles of the blood, the veins and the pulsating vesicle, become plainly visible. Wherefore, if the leaping point together with the veins and blood, which are all conspicuous as one single organ at the first beginning of the embryo, be accepted as the heart (the parenchyma of which is superadded to the vesicle later in the formation of the embryo), it is manifest that, accepted in this sense, that is, as an organ composed of parenchyma, ventricles, auricles, and blood, the heart in animals is in very truth, as Aristotle would have it, the principal and first generated part of the body; of which part, however, the first and foremost part is the blood, both by nature and in the order of generation."[175]

In the following third passage of the same treatise no reconciling interpretations of the master's words are to be found; flat disagreement with Aristotle is declared; and the "Sun of the Microcosm"[176] declines nearly to its simple modern status of a living pump! Harvey says:—

"Nor can I agree with Aristotle himself, who maintained that the heart is the primary generative part and that it is endowed with soul; for, truly, I believe the blood alone to be entitled to these distinctions, since the blood it is which first appears in generation; and that such is the case not only in the egg but also in every fœtus and very early animal embryo, shall at once be made plain.[177]

"At the beginning, I say, there appear the red leaping point, the pulsating vesicle, and filaments, derived thence, which contain blood in their interior. And, so far as can be discerned by accurate inspection, the blood is made before the leaping point is formed, and the blood is endowed with vital heat before it is set in motion by pulsation; and, further, as pulsation is begun in and by the blood, so at last it ends in the blood at the final instant of death. Indeed, by numerous experiments done upon the egg and otherwise I have made sure that it is the blood in which the power of returning to life persists, so long as the vital heat has not wholly vanished. And since the pulsating vesicle and the sanguineous filaments derived from it are seen before anything else, it stands to reason in my belief that the blood is prior to its receptacles—the contained, that is, to its container—since the latter is made for the use of the former. Therefore, it is probable that the filaments and the veins and then the vesicle and at length the heart, having organs destined to receive and retain the blood, are made for the sole purpose of transmitting and distributing it, and that the blood is the principal part of the body....

"Therefore, relying with certainty upon what I have observed in the egg and in the dissection of living animals, I maintain against Aristotle that the blood is the primary generative part; and that the heart is its organ, destined to send it on a circuit. Surely the function of the heart is the propulsion of the blood, as is admirably clear in all animals that have blood; and in the generation of the chick the same duty falls to the pulsating vesicle, which in the very early embryos of animals[178] no less than in the egg I have often exhibited to view as something more minute than a spark, beating and when in action contracting itself and at the same time pressing out the blood contained in it, and in its relaxation receiving the same afresh."[179]

Whether in studying the foregoing passages we read Harvey's earlier jottings in his private note-book or the deliberate statements published in his old age, it is evident that to his mind the question of the primacy of the blood versus the primacy of the heart depends for answer upon the further question whether in the development of the embryo the blood be made before the heart, or the heart before the blood. In no other part than one of these two can the primacy inhere, for him; and whichever of these two has the priority must be, to Harvey's mind, the origin of the other and of the remaining parts and must continue to be the "principal part" of the body throughout life. The matter of the primacy thus resolves itself into one of well-devised and accurate observation; and the discoverer is once more upon the ground where his undying laurels grew. He, therefore, deals no longer "without demonstration," as in the second Exercise to Riolanus, but makes report of actual observations and so gives ocular evidence in support of his views, remembering, it may be, that he had said to Riolanus: "Soon, perhaps, I shall make public things even more wonderful and destined to cast even greater light on natural philosophy."[180] Harvey's contemporary Milton said to Parliament: "Truth is compar'd in Scripture to a streaming fountain; if her waters flow not in a perpetuall progression, they sick'n into a muddy pool of conformity and tradition."[181] These words seem timely as we note the great discoverer, magnifying glass in hand, searching in incubated eggs for an answer to the question, now wholly obsolete, whether the primacy of the heart should not give way to the primacy of the blood.

"Surely," says Harvey, "this investigation is one of great moment, to wit: whether or no the blood be present before the pulse; and is the point[182] derived from the veins or the veins from the point? So far as I have been able to observe, the blood appears to exist before the pulse; and I will show cause for this opinion as follows: On a Wednesday evening I put three eggs under a hen; and having come back on the Saturday, a little before the same hour, I found these eggs cold as though deserted by the hen. I opened one of them, nevertheless, and came upon the beginning of a chick, namely, a red sanguineous line at the circumference,[183] but at the centre instead of the leaping point a point which was white and bloodless. By this sign I perceived that the hen had left off sitting not long before. So I caught her, shut her up in a box, and kept her there the entire night; that is, after I had put under her the two remaining eggs together with other fresh ones. What was the result? Next day in the very early morning both eggs had revived; and at the centre the beating point itself was visible, much smaller than the white point; out of which, that is, out of the white one, it made its appearance in diastole only, like a spark leaping forth from a cloud: so that the red point seemed to me to flash out of the white point; the leaping point being generated in the latter, in one way or another; and the blood to be already in existence, when the leaping point is brought into existence or at least into motion. Indeed, I have very often found that even when the leaping point lies still and devoid of all motion as though quite dead, it recovers motion and pulsation again if warmed afresh. From the foregoing I judge that in the order of generation the point and the blood come into existence first; but that pulsation does not come on till afterward. Certainly this is settled, viz.: that of the future embryo nothing at all appears on this day[184] except the sanguineous lines and the leaping point and also those veins which grow all from one trunk (as this grows from the leaping point) and are dispersed throughout the entire colliquative[185] region in very many ramified filaments....

"Toward the end of the fourth day and the beginning of the fifth the sanguineous point is already increased in size and is seen to be turned into a small and very delicate vesicle containing blood within itself; which blood it drives out at every contraction, and receives afresh when its diastole takes place.

"Up to this stage I have found it impossible to discriminate between the vessels; for the arteries are not to be distinguished from the veins either by their coats or by the pulse; and so I think it best to style all the vessels, indiscriminately, veins or, with Aristotle,[186] venous canals....[187]

"On the sixth day ... the parenchyma of the heart grows on to the pulsating vesicle; and shortly afterward the rudiments of the liver and of the lungs are discernible."[188]

It is clear that Harvey's hens did not very often take such well-timed steps against Aristotle; for in another passage of his treatise on generation, in summing up its events and their order, he frankly states the difficulties which render uncertain the question of priority between the blood and the heart. He speaks of "the first generated and generative part; that is to say, the blood together with its receptacles or, if you prefer, the heart with its veins."[189] A few lines further on he says:—

"In the generation of this first part (which is accomplished in the egg on the fourth day) although I have not been able to observe any order, because all portions of the part aforesaid (namely, the blood, the veins and the pulsating vesicle) appear at the same time; nevertheless, my belief would be, as I have said, that the blood is present before the pulse; and that, therefore, in obedience to a law of nature the blood is prior to its receptacles, that is, to the veins."[190]

In Harvey's first publication, of 1628, we have read:—

"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."[191]

In his last publication, of 1651, we have read:—

"So far as can be discerned by accurate inspection, the blood is made before the leaping point is formed, and the blood is endowed with vital heat before it is set in motion by pulsation; and further, as pulsation is begun in and by the blood, so at last it ends in the blood at the final instant of death."[192]

Harvey's own words in the foregoing two passages effectively sum up both the nature of his doctrine that the blood is the first part of the body to live, and the nature of his evidence. But the words of the second passage foreshadow a closely related doctrine, advanced and held by him on the evidence of observation, viz.: that the blood, being the first part to live, is also the last part of the body to die. That the first part to live is always the last to die, is a doctrine set forth by Aristotle. This, Harvey seems to accept without question and to apply upon proper evidence to the blood; as he accepts and warmly upholds the ancient master's doctrine that there is a primacy of the body. The results of observation have forced Harvey to transfer this primacy from the heart to the blood, but it is the Aristotelian primacy still. Presently he shall show us that the blood is not only the first part to live, but the last to die. Before he does so, however, let Aristotle speak for himself, saying briefly:—

"The point[193] of origin [of the rest of the body] is the first thing generated. The point of origin in the animals which possess blood is the heart; in the rest, the analogue thereof, as I have often said. Moreover, the fact that the heart is the first thing generated is evident, not only to the senses, but from its death.[194] For therein life ceases the last; and in all cases the last generated is the first to make an end, the first generated, the last to make an end; nature, as it were, doubling back and returning upon her point of origin whence she came.[195] For generation is the change from not being to being; destruction is the reverse change, from being to not being."[196]

Aristotle does not tell us why "in all cases ... the first generated" is "the last to make an end," and vice versa. Let it suffice that Harvey accepts this sweeping doctrine. Now let him complete his evidence in favor of the primacy of the blood by showing that the blood is not only the first part to live and to live tenaciously, but the last part to die.

In a passage of the treatise On the Motion of the Heart and Blood, we have already read Harvey's promise to publish observations

"on the formation of the fœtus, where numerous problems of the following order can find a place: Why should this part 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]

That Harvey should have printed this passage in 1628, in the same work with his repeated eulogies of the Aristotelian heart, shows that the idea of the possible primacy of the blood must have been in his mind early. It was, indeed, so from the jotting down of his private notes of 1616, to the publication of the Exercises to Riolanus in 1649 and the treatise On Generation in 1651. The same mental attitude is revealed, perhaps more strongly, in the following passage of an earlier chapter of Harvey's treatise of 1628. Here we come upon the thought that it may be the blood, and neither ventricle nor auricle, which is the last to die. Harvey says:—

"Besides this, however, I have occasionally observed, after the heart and even its right auricle[197] had ceased their pulsations as though in the act of dying, that an obscure motion and flow and a sort of palpitation manifestly remained in the blood itself contained in the right auricle, so long, that is, as the blood appeared to be imbued with heat and spirits. Something of the sort is very plainly to be seen at the beginning of the generation of an animal, in the hen's egg within the first seven days of incubation. There is present, first and before all else, a drop of blood which palpitates (as Aristotle also noted); from which, when growth has taken place and the chick has been formed to some extent, the auricles of the heart are made; and in these, which pulsate perpetually, life inheres....

"Whoever, therefore, shall choose to investigate more closely will say that the heart is not the first to live and the last to die, but that the auricles, and the part which answers thereto in serpents, fishes, and such animals, are alive sooner than the heart itself and also die later than the heart. Whether even earlier the blood itself, or the spirit, have not an obscure palpitation of its own, which it has seemed to me to retain after death, may well be questioned; and whether we should not speak of life as beginning with palpitation."[198]

It is plain that fibrillar contractions of cardiac muscle misled Harvey into thinking and writing of "an obscure motion and flow," of "an obscure palpitation," of the blood itself within the dying auricle. It is plain that when he wrote his most famous treatise he was loath, even under Aristotle's leadership, to reach out so far beyond the evidence of the senses as to attribute the palpitation of the visible drop of blood in the very early embryo to anything but the hot blood itself. Later, in his treatise On Generation, he published a passage which in some ways runs parallel with the foregoing. In the earlier passage the results of observation are brought forward as food for thought; in the later one, as proofs of a theory, fully, clearly, and emphatically stated by a thinker who is near the end of life and is imparting his final judgment. This later passage is as follows:—

"In whatsoever part of the body heat and motion have their beginning, in that same part life also first arises and therein is extinguished last; nor may it be doubted that there, too, life has its innermost home, that there the soul itself has fixed its seat.

"The life then inheres in the blood (as we read also in Holy Writ[199]), because therein the life and the soul are manifest first and fail last. For, as I have said, in the dissection of living animals I have found repeatedly that, though the animal be dying and breathe no longer, nevertheless, the heart pulsates for some time and keeps the life in it. Moreover, when the heart is quieted you may see movement surviving in the auricles, and latest in the right auricle; and at length all pulsation ceasing there, you may find in the blood itself a kind of undulation and obscure agitation or palpitation, the last indication of life. And anyone can perceive that the blood retains in itself to the last the heat which is the author of pulsation and life; if this heat is once wholly extinguished and the blood now is blood no more, but cruor, so there is left no hope of a return to life again. Nevertheless, after all pulsation has disappeared, both in the egg, as I have said, and in dying animals, if you will make a gentle warm application, in the former case to the leaping point, in the latter to the right auricle of the heart, you shall see movement, pulsation, and life, renewed immediately by the blood; provided it have not utterly lost all its innate heat and vital spirits."[200]

How readily heat from without can revive the cool leaping point, is strikingly set forth by Harvey in another chapter of this treatise On Generation. He says:—

"Moreover, if an egg be exposed too long to a colder atmosphere, its leaping point pulsates less often and stirs more languidly; but if a warm finger be applied to it, or any other bland source of warmth, straightway it recovers strength and vigor. Indeed, when such a point has become gradually weak and though full of blood ceases to move at all and gives no sign of life, seeming utterly to have succumbed to death, if my lukewarm finger be placed over it for the space of twenty pulsations of my artery, behold! the little heart revives once more, becomes erect, and renews its pristine dance as though come back from Hades. This I myself and others, too, have brought about again and again by means of gentle warmth of any kind, such as that of a fire or of tepid water; thus at our pleasure being able to give over the poor little soul to death, or call it back to the light."[201]

As in the embryo the leaping point may be revived by external warmth, so may the heart in the full-grown bird. In his treatise of 1628 Harvey says:—

"In the pigeon, at any rate, at an actual experiment, after the heart had wholly ceased to move and even the auricles had left off moving, I placed my finger, wetted with saliva and warm, upon the heart and kept it there for a while; as the result of which fomentation the heart, as though restored to strength and life again, and its auricles with it, were seen to move and contract and relax themselves and, as it were, to be recalled from death."[202]

In his treatise On Generation, Harvey confirms the doctrine of the primacy of the blood by citing observations made upon sluggish or hibernating animals and also certain morbid phenomena in man, as follows:—

"This, too, clearly follows from many observations; especially the cases of certain animals which possess blood yet live a long time without a pulse; and of some which lie hidden the whole winter and, nevertheless, continue alive, although meanwhile all movement of the heart has ceased and their lungs enjoy a rest from breathing, like people who lie half dead and pulseless in syncope or faintness or hysterical affections."[203]