Harvey, William

(b. Folkestone, Kent, England, 1 April 1578; d. London or Roehampton, Surrey, England, 3 June 1657)

physiology, anatomy, embryology, medicine.

Harvey was the eldest son of Joan Halke and Thomas Harvey, a yeoman farmer and landowner who in later life engaged in commerce and rose to the gentry; five of William’s six brothers enjoyed even greater success as London merchants.¹ After attending King’s School, Canterbury, Harvey studied arts and medicine at Gonville and Caius College, Cambridge, from 1593 to 1599. He then completed his education at the University of Padua, the leading European medical school; among his teachers were the celebrated anatomist Girolamo Fabrici and, probably, the Aristotelian philosopher Cesare Cremonini. Upon receiving his doctorate in medicine in April 1602, Harvey returned to England and took up the practice of medicine in London; in 1609 he was appointed physician to St. Bartholomew’s Hospital. In 1604 he was married to Elizabeth Browne, the daughter of Lancelot Browne, a prominent London physician; they had no children.

In 1607 Harvey was elected a fellow of the Royal College of Physicians, in whose professional and political affairs he took an active interest for the rest of his life. Among the positions he held in the college was that of Lumleian lecturer on surgery from 1615 to 1656, and in 1627 he became one of the seven elect of the College; but after 1630 his duties as royal physician increasingly curtailed his participation in the business of the college. In 1651 he donated money to the college for building and furnishing a library, which was officially dedicated in 1654; in 1656 he gave it an endowment to pay a librarian and to present an annual oration, which continues to be held in his honor.

In 1618 Harvey was appointed one of the physicians extraordinary to James I, a position which he retained after the accession of Charles I in 1625; in 1631 he was promoted to physician in ordinary and in 1639 became senior physican in ordinary. Over the years he came to be on increasingly close terms with Charles I and did not conceal his loyalty to his memory even under the Commonwealth. From 7 April to 27 December 1636 Harvey traveled in the retinue of his friend Thomas Howard, earl of Arundel, on a special royal embassy to Emperor Ferdinand II at Regensburg; this provided him with the opportunity to meet a number of prominent Continental physicians, and on a side trip to Italy he also helped to look for paintings for the royal collection. The king apparently took an interest in Harvey’s scientific work and provided him with deer from the royal parks for some of his investigations. Harvey accompanied the king on his visit to Scotland in 1633 and on his Scottish campaigns of 1639, 1640, and 1641. Following the outbreak of the Civil War in 1642 Harvey seems to have been in constant attendance on the king and remained with him at Oxford, from the winter of 1642 until he surrendered himself to the Scots in May 1646. In November 1646 Parliament granted Harvey’s petition to attend the captive king at Newcastle; after the king was handed over to Parliament in January 1647, Harvey returned to London. Now a widower, he lived at the various residences of his brothers in and around the city and resumed his medical practice on a limited scale; he seems to have suffered only minor difficulties as a result of his royalist sympathies.

Harvey had a broad interest in literature and art as well as medicine and philosophy, and among his friends and acquaintances were Francis Bacon, Robert Fludd, George Ent, Charles Scarburgh, John Selden, Thomas Hobbes, and John Aubrey, who has left an account of him in his Brief Lives. Harvey seems to have been well liked by those who knew him, although he was an outspoken man and perhaps somewhat short-tempered. In his later years he suffered from gout and kidney stones and apparently was not averse to ending his sufferings by an overdose of laudanum; he is reported to have survived one such attempt in 1652, only to die of a stroke in 1657, at the age of seventy-nine.

Throughout his life, whether at London, at Oxford, or on his various travels, Harvey was an untiring observer of animal life in all its forms. The earliest evidence of his scientific activities comes from his anatomical lecture notes, written in 1616; these notes formed the basis of the anatomical demonstrations that he conducted for the College of Physicians in that year, and periodically thereafter, as part of his duties as Lumleian lecturer.² In preparing these notes he relied heavily on the comprehensive Theatrum anatomicum (1605) of Gaspard Bauhin, supplemented by an extensive knowledge of other medical and anatomical authors. As was usual at the time, his treatment of anatomy included extensive discussions of the functions of the parts; and in judging the views of earlier authorities Harvey was generally independent and critical, occasionally impatient, but not rebellious against the structure of traditional medical thought as such. Throughout his life he retained a sense of identity with his predecessors, even after he had rejected some of their most basic doctrines.

From these notes it is clear that Harvey had already begun the original investigations of the motions of the heart, respiration, the functions of the brain and spleen, animal locomotion and generation, comparative and pathological anatomy, and various other subjects that were to occupy his attention for the rest of his life. From statements in his published works it appears that he contemplated a vast research program that would lead to publications on all of these subjects, but only his works on the heart and on generation were actually seen in print. Many of his notes and manuscripts were lost when his rooms at Whitehall were sacked in 1642, and most of the rest were presumably destroyed together with his new library at the College of Physicians by the Great Fire. Aside from the lecture notes, only the rough drafts of the treatises “De musculis” and “De motu locali animalium” have survived; there are also a number of letters on scientific subjects.

Nevertheless, the publication of the relatively short Exercitatio anatomica de motu cordis et sanguinis in animalibus (1628), in which he announced his discovery of the circulation of the blood, was sufficient to ensure Harvey a place of first importance in the history of science and medicine. By this discovery he revolutionized physiological thought, which since antiquity had been based to an important degree on assumptions about how materials flow through the blood vessels. Beyond this, he inspired a whole new generation of anatomists who sought to emulate his methods in the study of animal functions. And, more generally still, his work was one of the major triumphs of early modern science, and thus helped to generate the enthusiasm for science that came to dominate European intellectual life during the second half of the seventeenth century.

On the other hand, Harvey’s work also had important connections with the medicine and philosophy of the Renaissance. His general philosophical outlook was quite traditional, and he had little regard for the mechanical and chemical philosophies that captured the imaginations of many of his contemporaries. His reliance on observation in the study of nature was a direct outgrowth of the anatomical revival of the sixteenth century, which had broadened into an interest in comparative anatomy by the early seventeenth. He was perhaps more interested in the study of function than earlier anatomists had been; but almost from the beginning the anatomists of the Renaissance had found themselves criticizing and modifying Galen’s doctrines on function as they increased their knowledge of structure, and Harvey was able to build upon their achievements. Again, Harvey made more effective use of vivisection in the study of function than had been done earlier, but such observations were not new in themselves; and on the other hand, Harvey continued to rely heavily on purely structural considerations in attempting to infer the actions of the parts. Finally, in spite of his frequent insistence on relying only on the evidence of the senses in the study of nature, a deeply theoretical, almost speculative, strain manifests itself throughout his work; indeed, in Harvey, the thinker and the observer are so intimately united that it is impossible to separate them.³ He undoubtedly observed more, and more carefully, than had his predecessors, and without this he would not have discovered the circulation; but his originality stemmed not from the amassing of observations per se but from his remarkable gift for perceiving and pursuing the theoretical implications of his observations.

One trait which distinguished Harvey from many of his medical predecessors was his preference for the physiological doctrines of Aristotle to those of Galen. Most earlier physicians were Aristotelians in their general philosophical outlook; but since the Galenic revival in medicine of the early sixteenth century there had been a division over many physiological questions between academic physicians, who usually supported Galen, and academic philosophers, who generally defended Aristotle. Thus at Padua in the early seventeenth century the anatomist Fabrici was a fairly loyal, although not uncritical, follower of Galen with regard to physiological matters, while the philosopher Cremonini was an uncompromising exponent of Aristotle. Yet prior to Harvey there were a few physicians, most notably Andrea Cesalpino and Caspar Hofmann, who strongly supported Aristotle against Galen, and Harvey’s views resembled theirs in a number of important respects, especially in the area of cardiovascular physiology. There was also an important difference, however, in that these earlier men tended to make the vindication of Aristotle the main goal of their work, whereas Harvey used Aristotle’s biological writings as a reliable starting point for his own inquiries but did not shrink from disagreeing with them if it finally came to that.⁴

As Walter Pagel has emphasized, perhaps the most fundamental similarity between the biological outlooks of Aristotle and Harvey is the monistic conception of living substance.⁵ In this view the soul is not a separate immaterial substance that is superadded to, and acts upon, passive matter, but is the form, or tendency to perfection, of the body; thus there is only one living thing, having both material and immaterial aspects. A corollary to this idea was Harvey’s emphasis on the immanence of the vital powers in all the parts of the body, in contrast with’ many of his predecessors, who saw the activities of most parts of the body as manifestations of separable spirits or faculties which flow into the parts from a central source.

These trends found their most important expression in Harvey’s doctrine of the primacy of the blood, which he had already begun to develop when he wrote his lecture notes in 1616 and which in later years he seems to have regarded even more highly than his discovery of the circulation.⁶ For Harvey, animal life was first and foremost a property of a single homogeneous substance—blood—rather than the result of an interaction between diverse formed organs and causative agents. He took the main causative agents of traditional vitalistic physiology—spirits and innate heat—and reduced them to inseparable qualities of blood insofar as it is alive; furthermore, he thought that the soul itself inheres primarily in the blood and in a sense is identical with the blood.

In Harvey’s view, the first rudiment of the embryo to be generated is a drop of blood, which already exercises the basic powers characteristic of an animal before the existence of specialized organs. It carries on nutrition and growth before the liver or other nutritive organs have been formed; it exhibits pulsatile movement before the formation of the heart or other motor organs; and if the early primordium of a chick embryo is irritated with a needle, it reacts by obscure undulations, showing that it must have a form of sensation even before the existence of the nervous system. However, the blood needs the more specialized structures as instruments for the fuller exercise of its powers, as well as to secure its own growth and preservation; and therefore it proceeds to generate the rest of the body out of itself, using an innate, unconscious Idea as its exemplar. All other parts of the body originally receive life from the blood, and thereafter the blood continues to be the main repository of heat and vitality; its constant circulation through the body serves not only to nourish all the other parts but also to sustain their heat, spirits, concoctive powers, sensibility, and contractility. Thus the blood alone is truly alive per se, and the rest of the body is an appendage that serves the blood and lives by virtue of it.

Discovery of the Circulation . Harvey’s work on cardiovascular physiology began with a study of the heart and arteries, which before the discovery of the circulation were regarded as a separate functional system from the liver and veins. During the sixteenth and early seventeenth centuries the prevailing Galenic doctrines on both systems had come under frequent criticism; but whereas Galen’s ideas on the veins survived more or less intact, his teachings on the heart and arteries underwent considerable modification at the hands of an influential minority. Harvey’s early work was in direct continuity with this progressive tradition; when he wrote his anatomical lecture notes he had not yet discovered the circulation, but he had reached conclusions about the movements of the heart and arteries that were highly significant in their own right. It appears that for a time he considered publishing a separate treatise on this subject, and such an early work may even have formed the basis of the proem and first half of De motu cordis.⁷ Eventually, though, Harvey became aware of certain difficulties inherent in his conception of the heartbeat, which led him to reconsider the functions of the veins and thus to discover the circulation. But even afterward both Harvey and his contemporaries continued to regard his views on the motion of the heart and arteries as quite significant in themselves, apart from the broader theory.

In the standard physiology of the sixteenth century, the chief function of the veins was to convey nutritive blood from the liver to all the parts of the body. The right ventricle of the heart was considered part of this sanguineous system, its purpose being to transmit blood from the vena cava to the pulmonary artery for the nutrition of the lungs. The idea of the centrifugal flow of venous blood from the liver was one of the most convincing elements of Galenic physiology, since it seemed to follow of necessity from the anatomy of the veins. One could trace the pathway of the nutriment from the intestines through the mesenteric veins to the liver, and it seemed obvious that from there it would flow into the vena cava and then to all the other veins of the body. Before Harvey there was considerable dissatisfaction with the failure of this view to account adequately for the important anatomical relationship between the veins and the heart; but the existence of the tricuspid valve seemed to rule out the idea that the venous blood flows outward from the heart, which was the only alternative that suggested itself. Nor did the discovery of the venous valves by Fabrici in 1574 have much effect on these ideas. Once the valves became known, it seemed clear that without them all the venous blood would collect in the lower parts of the body; the valves were thought to prevent this, but without preventing the slight downward trickle necessary to replace the blood absorbed by the parts as nutriment.

During the sixteenth century the lungs, pulmonary vein, left ventricle, and arteries were generally considered to form a separate pneumatic system, concerned with transmitting vital spirit and natural heat to the entire body. The left ventricle and arteries were also thought to ventilate the innate heat through active dilatation and contraction; thus the left ventricle inhaled and exhaled through the pulmonary vein, while the arteries inhaled and exhaled through the pores in the skin. In addition, a small amount of blood from the right ventricle was supposed to pass through the cardiac septum to the left ventricle and arteries, but this was of only secondary importance.

During the later sixteenth and early seventeenth centuries a growing minority of anatomists, such as Felix Platter and Adrian van der Spiegel, came to hold a rather different view of the heart and arteries; they looked upon them primarily as sanguineous organs and considered the transmission of blood to the arteries to be one of the most important functions of the heart. This change in thinking resulted largely from the discovery and gradual acceptance of the pulmonary circulation, which was published by Realdo Colombo in 1559. Those who accepted this concept tended to minimize or even flatly to reject the idea that the movements of the heart and arteries serve to ventilate the innate heat. It now seemed clear from the structure of the left ventricle that its principal action is to receive blood from the lungs and expel it into the aorta, just as the right ventricle transmits blood from the vena cava to the lungs. This idea did not directly conflict with the idea that some of the blood from the vena cava flows outward through the peripheral veins, since the venous and arterial blood were generally thought to serve two different purposes: nutrition and vivification, respectively.

By the time he wrote his anatomical lecture notes in 1616, Harvey had accepted this new view of the heart and had added to it a concrete understanding of the movements of the heart and arteries based on extensive vivisectional observations.⁸ He originally undertook this study to settle an ancient controversy over whether the heart and arteries dilate and contract at the same time or in alternation, and whether the arteries pulsate actively or are passively distended by the impulsion of material from the heart. In antiquity techniques had been developed for exposing the heart in live animals in order to study its motions in relation to those of the arteries, and such investigations were resumed in the sixteenth century. But given the difficulty of distinguishing the movements of a rapidly beating heart, as well as other complicating factors, these observations failed to produce a clear resolution; and Harvey’s contemporaries were divided in their views on the coordination between the heart and arteries. There was more general, although not unanimous, agreement that the arteries pulsate actively, largely because it was thought that all of the arteries would not dilate simultaneously if the cause of the pulse were purely mechanical.

As Harvey emphasized in the lecture notes and De motu cordis, he was determined to settle these disputes and therefore refused to give up in the face of initial frustration and confusion. It is also evident from both accounts that his ultimate success resulted largely from the study of the hearts of dying animals, in which the events of the heartbeat are considerably slowed down and, therefore, more easily discernible. He also studied the simpler hearts of cold-blooded animals and observed excised beating hearts, both whole and in section. In addition, he took into account a great deal of purely anatomical data in attempting to determine the action of the heart.

In choosing the questions to be answered by his observations, Harvey was much influenced by a description of the heartbeat published by Colombo in 1559.⁹ In addition to maintaining that the arteries dilate when the heart is contracted, and vice versa, Colombo had focused attention on the actual nature of the heart’s movement. He asserted that this consists of a more relaxed phase, during which the heart receives blood into its ventricles, and a more vigorous phase, during which it transmits what it has received. This notion went against the prevailing view that both movements of the heart are active and that, if anything, dilatation is more vigorous than constriction.

Colombo’s description included a note of terminological confusion in that he referred to the more active phase of the heart’s movement as “constriction” and the more passive phase as “systole,” which also means constriction. Harvey was somewhat puzzled by this inappropriate use of the word “systole,” but his uncertainty seems to have led him to make a very fruitful distinction between the question of the activity or passivity of the phases of the heartbeat and the question of which phase is systole and which diastole. In the lecture notes Harvey sought to establish, first of all, that the heartbeat consists of only one active movement, to which he gave the neutral designation “erection,” since at this time the apex of the heart appears to be lifted up; this is followed by a completely passive relaxation. During erection the heart strikes the chest and its flesh changes from soft to hard, and at the same time the pulse of the arteries is perceived; erection is slightly preceded by the obvious contraction of the auricles, during which they expel their blood and become whiter. Indeed, the beat of the heart begins with the auricles and then proceeds to the apex of the ventricles, so that “the auricles arouse the somnolent heart.”

Having established the sequence of events involved in the heartbeat, Harvey addressed himself to showing that erection, the proper motion of the heart, represents the contraction of its ventricles. A number of considerations supported this conclusion. If a beating heart is punctured, blood is forcefully expelled during erection; the heart becomes whiter during erection; the dissection of a beating heart shows that its walls become thicker during erection, which means that its cavities must become smaller. Harvey also felt that the entire structure of the heart, with its component fibers, valves, and the chordae tendineae, supported the view that its essential action is to contract and expel materials rather than to dilate and attract them.

In addition, it seemed more reasonable that the heart should contract when the arteries dilate, since there could be no passage of material from one to the other if they dilate and contract at the same time. Indeed, Harvey maintained that the pulse of the arteries is simply the result of the impulsion of blood by the heart and is not an active movement. When an artery is cut, blood is expelled from it more vigorously during the contraction of the heart; the pulsation of the pulmonary artery but not of the pulmonary vein likewise supported the view that the pulse is caused by the impulsion of blood, as did the comparative anatomy of the arteries: the more vigorous the pulse of an animal, the thicker its arteries. Harvey repeatedly compared the pulse of the arteries to the inflation of a glove; this concrete analogy, which he seems to have borrowed from Gabriele Falloppio,¹⁰ probably helped him to overcome the standard objection that a purely mechanical impulse could not be transmitted instantly to all of the arteries.

In the lecture notes Harvey summarized his conclusions thus:

From these things it is clear that the action of the heart insofar as it is moved is [to transfer] blood from the vena cava to the lungs through the pulmonary artery, and from the lungs to the aorta through the pulmonary vein. When the heart is relaxed, which is first, there is an entrance of blood into the right ventricle from the vena cava, and into the left ventricle from the pulmonary vein. When it is erected, or contracted, it forcefully propels [the blood] from the right [ventricle] into the lungs, and from the left [ventricle] into the aorta, whence the pulse of the arteries.¹¹

Or, as he put it more succinctly, “Action: thus relaxed receives blood, contracted scups it over; the entire body of the artery responds as my breath in a glove.”¹²

One of the consequences of Harvey’s new view of the movement of the heart was that the amount of blood transmitted from the vena cava to the aorta at each beat had to be fairly large. Because the heart does not dilate actively, there must be an appreciable influx of blood into its ventricles to account for each cardiac diastole, and similarly the passive distention of the arteries requires that the heart expel a significant amount of blood into them at each systole; and because Harvey was convinced of the competence of the heart valves, this transfer had to be irreversible. It was to be some time before Harvey saw the full implications of so large a rate of transmission, but by 1616 it seems already to have indirectly weakened his adherence to Galen’s doctrines on the veins. From a number of brief references in the lecture notes it appears that he still accepted a flow of some blood from the liver and vena cava to the peripheral veins,¹³but he attached much greater importance to that part of the blood which passes through the heart and lungs to the arteries; indeed, at one point he asserted that “the whole mass of the blood” reaches the body by this route.¹⁴ Thus the arteries had replaced the veins as the principal blood-distributing vessels, and the vena cava was more concerned with transporting blood from the liver to the heart than from the liver to the peripheral veins.

Otherwise, Harvey noted only two major points about the veins in the lecture notes: the heart, rather than the liver, is their governing principle (arché); but, unlike the arteries, they do not pulsate because “they have many valves opposed to the heart” which break off the impulse caused by cardiac contraction.¹⁵ The latter point is of some importance, for it shows that in Harvey’s view the significant orientation of the venous valves was not upward in the body, as was previously thought, but inward toward the heart; this probably helped prepare him for the idea of centripetal venous flow once he saw the need for a return of blood from the arteries to the heart.¹⁶

In the first half of De motu cordis Harvey presented his conclusions about the movements of the heart and arteries in a more developed form, now bolstered by an additional wealth of vivisectional, anatomical, pathological, and embryological observations. In the proem he gives a devastating critique of Galen’s doctrines on the motions of the heart and arteries, especially the idea that these motions serve a ventilating function. In chapter 1 he describes how he first took up the study of the movement of the heart and eventually decided to publish his findings. In chapters 2, 3, and 4 he presents his conclusions about the ventricles, arteries, and auricles, respectively. Chapter 5 contains a summary of his views, with emphasis on the idea that the overall action of the heart is the constant transmission of blood from the vena cava to the aorta; he aptly describes this as a “swallowing” of blood from one vessel by the other. In chapters 6 and 7 he defends the pulmonary circuit of the blood, an essential corollary to his view that the action of the four-chambered heart is to bring about such a constant transmission of blood from the vena cava to the aorta.

In chapter 8 Harvey relates how he went beyond this early work on the heart and arteries to the discovery of the circulation. From this account it seems clear that he first conceived of the centripetal flow of venous blood as a necessary consequence of his conclusions about the heartbeat, rather than as the result of a direct investigation of the veins. He realized that over a relatively short period of time the heart transmits from the veins to the arteries even more than the whole mass of the blood; the rate of transmission is in fact so large that if it took place in only one direction, the veins would soon be drained and the arteries filled to bursting. Only if blood somehow returns from the arteries to the veins at the periphery could these absurdities be avoided.

Although by 1616 Harvey had assumed that the heart transmits an appreciable portion of blood at each beat, he had not yet realized the cumulative effect of such a large rate of transmission. What brought this problem to his attention is not certain, but it is possible that his thinking was stimulated by the views of a contemporary. In a book published in 1623, Emilio Parigiano maintained that there must be a significant reflux of blood from the aorta to the left ventricle during each cardiac diastole. Among his arguments was the following: “Since the heart in systole expels the larger part of its blood into the aorta, and that in scarcely a moment of time, the aorta would always be so filled with blood that it could receive no more, while the heart... would be emptied in a few beats.”¹⁷ Both problems would be eliminated if there were a constant return of blood to the heart through the aortic valve. It is not certain whether Harvey actually read this work before discovering the circulation,¹⁸ but the terms of the argument are quite similar to those that first led him to conceive of a return of blood to the heart through the veins. Parigiano himself did not attach great importance to the argument, since he accepted the need for a reflux of blood largely on other grounds, but it might have taken on new significance for Harvey against the background of his detailed study of the heartbeat and his firm belief in the effectiveness of the aortic valve.

In any case, Harvey’s statement in De motu cordis indicates that something aroused his interest in the question of how much blood the heart transmits from the veins to the arteries and led him to undertake a searching reexamination of the action of the heart with this specific question in mind. It will be noted that he took account of anatomical as well as vivisectional factors:

I often and seriously considered, and pondered at great length, how large would be the amount [of blood transmitted by the heart, as judged] from the dissection of live animals for the sake of experiment, from the opening of arteries, and from diverse investigations; also from the symmetry and magnitude of the ventricles of the heart, and of the vessels entering and leaving them (since Nature, who does nothing without purpose, would not have endowed these vessels with such a large proportional size without purpose); also from the elegant and careful construction of the valves and fibers, and from the rest of the structure of the heart, as well as from many other things.¹⁹

Harvey went on to state that it was from this inquiry into quantity that he first inferred the necessity of centripetal venous flow, which he subsequently confirmed by more direct means:

[When I had thus considered] how large the amount of transmitted blood would be, and in how short a time the transmission would take place, I noticed that the juice of the ingested aliment could not supply [this amount] without our having the veins emptied and completely drained on the one hand, and the arteries disrupted by the excessive intrusion of blood on the other, unless the blood somehow permeates from the arteries back into the veins, and returns to the right ventricle of the heart. I began to consider whether [the blood] might have a kind of motion, as it were, in a circle [motionem quandam quasi in circulo], and this I afterward found to be true [quam postea veram esse reperi].²⁰

Harvey then described the flow of blood from the left ventricle through the arteries, and back to the right ventricle through the veins, and compared this to the passage of blood through the lungs.

It is interesting that Harvey should distinguish two chief moments in the early development of his thought: his initial surmise of return venous flow as a solution to the quantitative problem and the later idea of a quasi-circular movement of the blood. To judge from his statement, it was only when he began to think of the movement of the blood precisely as circular that he was fully aware of having made an important new discovery; in other words, it appears that the metaphor of the circle played a significant role in enabling him to see through the complexity of his observations to a clear and simple conception of the movement of the blood. This is not to suggest that Harvey was looking for a circular pattern before he began thinking of venous return, but that at an early stage thereafter the possibility of a constant circular motion occurred to him and then served as the leading idea in the further clarification of his thought. That circularity per se should have caught his attention probably stemmed from the preeminence and preservative character that were attributed to circular motion in traditional natural philosophy; indeed, as Walter Pagel has shown, this tradition by itself had led a number of earlier men to associate circularity with the heart or the blood on purely speculative grounds.²¹ That Harvey shared these ideas about circularity is clear from the continuation of the passage just cited, in which he related the movement of the blood to other circular and quasi-circular processes in the atmosphere and the heavens.

It is not clear how long before 1628 these developments in Harvey’s thinking occurred. Some statements in De motu cordis seem to suggest an early date; but although Harvey made additions to his lecture notes several times during the 1620’s, it was apparently not until 1627 or even later that he added a brief description of the circulation.²² Moreover, the draft of his treatise on locomotion, written in 1627, contains numerous references to the functions of the heart but none to the circulation. Thus it may actually have been quite late that Harvey made the discovery.

In the second half of De motu cordis Harvey presented evidence to confirm the circular movement of the blood. First of all, in chapters 9 and 10 he strengthened the original quantitative argument by showing that the heart must expel at least some blood to the arteries at each beat and by making a rough calculation of the resulting rate of transmission. Thus, even if the amount expelled at each beat is as small as one dram and if the heart beats, say, 1,000 times in half an hour, then it still follows that in a relatively short time the heart will have transmitted more blood than the ingested aliment or the venous contents could supply. That all the blood can be rapidly evacuated from an animal by opening a large artery likewise shows how large is the rate of transmission. Furthermore, if the vena cava of a live snake is pinched, the beating heart rapidly empties itself of blood, while if the aorta is pinched, the heart soon becomes engorged with blood.

In chapters 11 and 12 Harvey sought to demonstrate by the use of ligatures that there is a passage of blood from the arteries to the veins at the periphery. If an arm is ligated so tightly that the arterial pulse is cut off, then it soon becomes pale and bloodless, while the arteries above the ligature become swollen with blood; but if the ligature is loosened sufficiently to restore the pulse, the arterial swelling above the ligature subsides and the arm becomes suffused with the blood that is allowed to flow in. Now the veins of the arm become swollen with blood—but only below the ligature, which means that this blood must flow into them from the arteries at the periphery rather than from the central veins. If such a swollen vein be opened as for bloodletting, within about half an hour most of the blood in the body can be evacuated from it; this provides an index of the amount of blood that flows from the heart into the arteries and from the arteries into the veins. Return venous flow is a necessary consequence of this rate of transfer, as well as of the rate of transfer from the veins to the arteries through the heart.

In chapter 13 Harvey went on to give a more direct demonstration of centripetal venous flow, based on the existence of the venous valves. He stressed the cardiocentric orientation of the valves and noted that a probe can be inserted inward through them but not outward. He also showed that if an arm is ligated to make the veins swell, then by drawing a finger along a vein with some pressure one can push blood inward through the valves but not outward. Furthermore, if a segment of vein is emptied by applying pressure with one finger and then squeezing the blood inward through a valve with a second, it will be apparent that it refills from the distal end of the vein when the first finger is removed. And, Harvey added, if the latter procedure be repeated a thousand times in succession, it will again be apparent on quantitative grounds that the blood must circulate.

In chapter 14 Harvey summarized his main arguments, and in chapter 15 he made some tentative suggestions about the purpose of the circulation. In chapter 16 he showed how the circulation could explain a number of previously inexplicable phenomena. Thus the ability of a localized affection, such as a snakebite, to rapidly influence the entire body results from the inward flow of a noxious substance through the veins, followed by its dispersal to the entire body through the arteries. Also, a number of problems relating to the mesenteric vessels would be eliminated by the idea of a rapid circulation of blood through them, with a gradual addition of chyle to the blood. Finally, in chapter 17 Harvey presented a wealth of anatomical evidence in support of his view, although all of this relates only to the heart and arteries rather than to the circulation as such.

The circulation was widely discussed during the twenty years following the publication of De motu cordis, and much of the reaction was quite favorable. The idea also found some major opponents, though, and in 1649 Harvey published Exercitationes duae de circulatione sanguinis, in which he replied to Jean Riolan and other critics. Among other points, Harvey sought to confirm that an appreciable portion of blood must be expelled at each beat of the heart (which in his view was the main buttress of the circulation), and that the arterial pulse is caused by this impulsion of blood. He also tried to show that the differences between venous and arterial blood are not so great as to make rapid conversions of one to the other seem implausible, and by various combinations of vascular ligation and section he gave more direct experimental demonstrations of the circulation than he had given in De motu cordis. Harvey also discussed aspects of the circulation in his treatise De generatione and in a number of letters.

A question which interested Harvey from the time when he first discovered circulation was that of its purpose, although his attempt to find an answer seems to have been complicated by his prior commitment to the idea of the primacy of the blood and by his views on respiration.²³ Most of his predecessors had regarded the heart as an inexhaustible source of lifegiving heat, which it imparted to the rest of the body through the arteries, using blood or spirits as a vehicle. By 1616, though, Harvey had come to regard the blood itself as the source of heat and vitality for the rest of the body; the heart was still the most important formed organ, but only in virtue of its role in distributing blood.²⁴

But when he later discovered the circulation, Harvey was faced with the question of why the blood should constantly return to its source, and an obvious answer seemed to be that it rapidly gives up its heat to the parts at the periphery and therefore returns to have it restored. For various reasons he did not think that the passage of blood through the lungs could be of major importance in restoring its vitality, and therefore he was brought back to the view that the heart is the actual source of heat in the body and the blood only its vehicle. This was what he tentatively proposed in De motu cordis, although the capitulation did not last for long and by the mid-1630’s he seems to have been more convinced than ever of the primacy of the blood.²⁵ When Caspar Hofmann criticized the notion of a repeated reheating of the blood by the heart in 1636, Harvey replied that he had proposed this view only for the sake of illustration and did not wish to insist upon it.²⁶ He maintained then and for the rest of his life that his failure to demonstrate the purpose of the circulation was not a valid reason for denying its existence.

Nevertheless, Harvey did not lose interest in finding a purpose for the circulation that would be consistent with the primacy of the blood. At times in his treatise De generatione he appears to fall back on the preservative character of circular motion per se, but elsewhere in this work and the letters to Riolan he seems to have had in mind a modified version of his earlier suggestion.²⁷ In this view, the source of heat in the body would be a kind of internal fermentation of the blood, but one which takes place primarily in the blood concentrated in the vena cava and heart; thus, hot blood from this source would be distributed through the arteries, give up its heat, and then return to the central mass to have it restored by renewed fermentation.

The idea of an internal fermentation of the blood also provided Harvey with an additional basis for asserting the primacy of the blood over the heart. Whereas he had earlier thought of auricular systole as the event which initiates the heartbeat, in his later works he maintained that this is preceded by a selfinduced swelling of the blood in the vena cava. As a result, blood is forced into the right auricle, which is irritated by the resulting distension; to rid itself of the irritating cause the auricle contracts, thereby distending and irritating the right ventricle, which also responds by contracting. The pulmonary artery is in turn distended and irritated to contraction, and a similar sequence occurs in the left heart. Thus the blood actually inaugurates its own movement, although, as Harvey conceded, one could also see the heart and blood as a functional unity which cooperates in causing the circulation and thus in preserving the life of the rest of the body.

Since antiquity ideas about the physiology and pathology of most parts of the body had been based to an important degree on assumptions about the functions of the heart and blood vessels; and therefore, by fundamentally changing the latter, Harvey pointed the way to a reform of all of physiology and medicine. At first many physicians sought to incorporate the circulation into the traditional framework with a minimum of other changes, but the middle decades of the seventeenth century saw the rise of new mechanical and chemical systems of physiology, which took the circulation as a basic assumption in the explanation of a wide range of vital phenomena; the mechanists in particular came to view the circulation of fluids through the solid parts of the body as almost the very essence of life. Subsequent developments in physiology have led to great changes in thinking about the functions of the circulation but have abundantly confirmed the importance of Harvey’s discovery as the cornerstone of modern physiology and medicine.

Sensation and Locomotion . In addition to the nutritive and pneumatic systems, which he amalgamated into one circulatory system, Harvey was also interested in the third great system of classical physiology: the organs concerned with locomotion and sensation. In 1627 he began work on a treatise entitled “De motu locali animalium” (“On the Locomotion of Animals”), which was primarily concerned with applying the general principles of Aristotle’s treatises on animal movement to a detailed study of muscles, nerves, and other organs involved in locomotion. Apparently he never completed the treatise, but the rough draft has survived and shows that he had begun to develop some important insights into the physiology of sensation and locomotion. These ideas were not published in Harvey’s lifetime, but in his treatise De generatione he discussed some related themes that had a direct and significant influence on the development of the concept of tissue irritability by his younger contemporary Francis Glisson.

Harvey’s predecessors generally regarded the brain as the principal organ of sensation and voluntary movement, by which they meant that the brain supplies the actual powers to carry on these activities to the sense organs and muscles through the nerves; thus, when one cuts the nerve leading to a part, one destroys its mobility or sensibility or both by cutting off its supply of the necessary faculties. The idea that sensation involves an inward movement of sense impressions to the brain was not unknown, but the function of the brain in sensation was looked upon primarily as centrifugal: the supply of the sensitive faculty. Furthermore, a fundamental distinction was made between organs of natural (involuntary) movement, such as the intestines and heart, whose power of movement is innate, and voluntary muscles, whose power of movement flows in from the brain.

For Harvey, by contrast, sensibility and contractility seem to be innate powers of the sense organs and muscles, although their preservation in these organs depends upon a constant inflow of blood, heat, and spirits through the arteries.²⁸ Sensation itself is primarily a function of the brain and is chiefly a centripetal process; it begins with the sensible object, passes through the sense organ and nerve, and terminates in the brain. Thus, “the use of a nerve is to communicate something sensible to the brain so that a judgement can be made,” while the brain itself is above all the Aristotelian sensorium commune, in which we perceive that we sense, and in which the objects of the different senses are compared with each other and unified.²⁹

According to Harvey, the role of the brain in voluntary movement is not to supply the motor faculty to the muscles but to act as the maestro del coro (choir-master), which harmonizes the movements of many individual muscles into purposeful actions.³⁰ If the nerve leading to a muscle is cut, what is destroyed is not its contractility but its ability to participate in useful, coordinated actions. Indeed, a cock can have its entire head cut off without its muscles ceasing to move, but the movements are disordered and without purpose; on the other hand, an individual muscle in an uninjured body can undergo spasms in no way subject to central control. Thus, for Harvey a muscle is like any other motor organ, in that it possesses contractility as long as it remains alive, a point which he expressed quite vividly by taking Aristotle’s comparison of the heart to a “separate animal” and applying it to the individual voluntary muscles;³¹ his conclusion that the heart may be considered a muscle implied as much a redefinition of muscle as of the heart.

In Harvey’s view, the role of the brain in the coordination of voluntary movement is contingent upon its primary function as sensorium commune.³² Following Aristotle, he maintained that every purposeful movement in an animal begins not from an internal impulse but from an external object that gives rise to an internal perception, then an appetite, and finally an action appropriate to the attainment of the object; thus it is because of its perception of the end that the brain can determine the action. Furthermore, Harvey seems to have thought that coordinated motion would be impossible without an inflow of sense impressions from the parts concerned; thus, he attributed the loss of coordination resulting from cutting a nerve to a destruction of the sensation of the part rather than to an interruption of motor impulses.

In the later treatise De generatione, Harvey proposed that in addition to the conscious sense perception that is conducted by the brain, there is an unconscious sensation that involves only the individual parts of the body.³³ He was impressed by the many instances in which involuntary actions can be evoked or altered by irritants applied directly to the parts concerned, without the irritant being consciously perceived as such. For example, an innocuous-tasting infusion of antimony can provoke the stomach to vomiting, as if the stomach itself could distinguish the harmful from the useful; similarly, the skin reacts very differently to two apparently identical pricks, one from a clean needle and one from a needle dipped in venom. Indeed, Harvey asserted, we have no other sure way of distinguishing the animate from the dead than by its movement in response to an irritant; and he argued that the ability to respond implies an ability to sense the irritant. Thus, just as we distinguish natural (involuntary) movements such as the heartbeat from animal (voluntary) movements that are made under the direction of the brain, so should we distinguish the natural sensation common to all living matter from the animal sensation that can result only from referring sense impressions to the brain. Natural sensation is “a kind of touch which is not referred to the sensorium commune, nor is it communicated to the brain in any way, so that in this kind of sense we do not perceive that we sense.” In simpler animals having no brain, and in fetuses prior to the formation of the brain, all sensations and motions are natural, while in mature higher animals both kinds are present. Thus there is a difference between the regulated actions which muscles perform under the direction of the brain and the spastic movements which they undergo in direct response to an irritant.

Generation . Since antiquity the generation of animals had been an important subject of speculation and observation for physicians and philosophers alike. of the two leading authorities in the field, Aristotle had made significant studies of the developing chick embryo, while Galen had described the anatomy of the reproductive organs and the fetus. Original observations in both areas began to be made again during the sixteenth century; and among Harvey’s immediate predecessors the most important contributions were those of his teacher Fabrici whose studies were broadly comparative in nature. By 1616 Harvey had already begun his own lifelong study of generation, and by about 1638 he seems to have completed much of the extant De generatione, although it was not published until 1651; a complementary treatise on the generation of insects was lost during the Civil War.³⁴

In the seventy-two exercises and eight appendixes of his long treatise, Harvey reported a wealth of observations on all aspects of reproduction in a wide variety of animal species; his attention was focused primarily on the domestic fowl and the deer as representatives of the ovipara and vivipara, respectively.³⁵ His description of the day-to-day development of the chick embryo was notably more accurate than earlier ones, while his direct study of viviparous generation by dissecting the uteri of hinds and does at various stages during mating and pregnancy was quite without precedent. These observations formed the basis of a critical evaluation of earlier theories of generation, especially those of Aristotle, Galen, and Fabrici; and, finding all of the latter deficient, Harvey went on to formulate the first fundamentally new theory of generation since antiquity. The originality of the theory consisted essentially in his using oviparous generation as a model for interpreting viviparous, whereas viviparous generation had previously been treated as the more fundamental type.

In accordance with the latter assumption, previous theories of generation had been largely concerned with defining the roles of semen and menstrual blood, which were considered to be the immediate precursors of the fetus in a relatively crude sense; by “semen” was meant the entire seminal mass emitted during coitus, while menstrual blood was thought to be directly incorporated into the fetus. According to Aristotle, semen emitted into the uterus by the male acts on blood supplied by the female to form the first rudiment of the fetus—the heart, which then directs the formation of the rest of the fetus from additional menstrual blood; thus there is a clear separation of efficient and material causes (paternal semen and maternal blood) at the onset of generation. In Galen’s view, on the other hand, the entire fetus arises from a mixture of semen emitted into the uterus by both parents, and thereafter is nourished by menstrual blood. In both theories the egg in oviparous generation is merely the vehicle for a delayed process in which the principal roles are still played by semen and slightly altered menstrual blood. Fabrici introduced a new emphasis on the importance of the egg itself as a distinct entity which is generated by the hen and in turn generates the chick; but he did not break entirely with the view that semen and menstrual blood are the main factors underlying oviparous generation, and he accepted the Galenic theory for the vivipara.

Much of Harvey’s work was concerned with eliminating the remaining vestiges of Aristotelian and Galenic doctrine from Fabrici’s theory of oviparous generation, thereby shifting attention completely to the egg itself as a primary generative agent, quite distinct from parental semen and blood, on the one hand, and from the future chick, on the other. He could find no evidence that the seminal mass of the cock either enters into or even touches the eggs during their formation within the hen; furthermore, he found that for a time the hen can continue producing fertile eggs after all detectable traces of semen have vanished from her body. To Harvey this seemed to offer solid evidence that the contribution of the cock’s semen to generation is indirect and incorporeal; it simply confers a certain fecundity on the hen and then plays no further role in the actual generation of the egg or the chick. Once endowed with this fecundity the hen can, entirely on her own, produce fertile eggs which will give rise to chicks resembling both herself and the cock. In trying to explain the transfer of this principle of fecundity from the semen to the hen, and from the hen to the egg, Harvey repeatedly cited the analogy of the spread of disease by contagion, in which mere exposure to a sick individual can engender within a second individual an internal principle which subsequently reproduces in him the same specific disease.

On the basis of his investigation of the reproductive tract of the hen, Harvey also rejected the view that the hen produces the egg by a slight alteration of her own blood. Instead, he maintained that the active role of the hen is confined to producing the first minute primordium of the egg; this primordium possesses its own nutritive powers, through which it actively generates the rest of the egg by the complete, substantial transformation of additional material supplied by the body of the hen.

Thus the completed egg contains no immediate parental secretion such as semen or menstrual blood, but neither, in Harvey’s view, does it contain any direct rudiment of the future chick prior to the onset of generation; instead, generation involves a second substantial change in which the same principle which transformed the maternal nutriment into the egg now transforms the egg into the chick. From this it is clear to what degree Harvey regarded the egg as an individual living entity, a distinct phase in the life cycle of the species which mediates between two successive generations.³⁶ The entire role of the parents in generation is to produce not a chick but a fertile egg, which subsequently gives rise to a chick through its own innate powers. For Harvey an egg was “a certain corporeal substance having life in potency”; it was “of such a kind that if all obstacles are removed it will develop into the form of an animal no less naturally than all heavy things tend downward, or light things move upward.”³⁷

Harvey maintained that within the egg the fetus emerges gradually from a homogeneous generative fluid, beginning with one first-formed part which actively creates the remaining parts in a definite order.³⁸ Furthermore, in the generation of the organs three processes take place simultaneously: the qualitative differentiation of the original generative substance, the acquisition of form, and increase in size. Harvey upheld these views in opposition to many contemporary physicians, who held that the fetus is completely passive in its own formation, that generation involves merely the separation and organization of preexisting substances, and that all the parts of the fetus are sketched out simultaneously at the onset of generation and subsequently undergo only growth. In adopting the idea of the gradual emergence of the fetus, which he termed “epigenesis,” Harvey followed Aristotle, although he considered a drop of blood, rather than the heart, to be the first-formed part. But the drop of blood soon gave rise to a pulsating vesicle around itself.

Harvey also disagreed with Aristotle’s reliance on a clear distinction between the efficient and material causes—semen and menstrual blood—to account for the onset of generation; instead, he stressed that there is only one factor, the egg, which is that from which as well as that by which the chick is generated.³⁹ Generation proceeds from the cicatricula (germinal disc), which, through an inherent principle, dilates into a small portion of perfectly clear fluid; this fluid, in turn, transforms part of itself into the first actual rudiment of the chick; a drop of blood. Thereafter the vital principle inheres primarily in the blood, which proceeds to transform the rest of the egg into itself at the same time that it forms the rest of the chick out of itself. There are of course causes antecedent to the egg in generation, but these do not participate directly in the formation of the fetus, so that at no point can the model of the separate artisan and artifact be applied to the latter process. Generation is simply an unfolding of the potentialities inherent in the fertile egg, with complete continuity between the vital activities of the egg, the fetus, and the mature animal.

Harvey’s study of viviparous generation began with an evaluation of the Aristotelian and Galenic theories, according to both of which the result of a fruitful coitus should be the mixing of the parental “genitures” in the uterus and the formation of the first rudiments of the fetus. However, in numerous dissections of deer from the royal parks at various intervals during and after the rutting season, as well as of other animals, Harvey could find in the uterus no prepared menstrual blood before coitus and no blood, seminal mass, or rudimentary fetus immediately afterward. Instead, he found that it is only some time after the male semen has vanished from the body of the female, and after a period in which the uterus is otherwise empty, that the first evidence of conception can be seen. Indeed, in the deer he could find no trace of the conceptus in the uterus for nearly two months after the rutting season, although it appears that in this he was misled by the unusual shape of the early embryo in the deer;⁴⁰ in other kinds of animals he found a much shorter interval.

Harvey interpreted his viviparous findings by analogy with his conclusions about oviparous generation. Instead of participating directly in the formation of the fetus, the semen of the male must confer fecundity on the female and her uterus (which Harvey regarded as the principal female generative organ in vivipara), thereby enabling the uterus to produce a fertile conceptus at some time after intercourse. This conceptus, he assumed, is the analogue of the egg rather than of the fetal chick; that is, the conceptus produced by the uterus is not the rudiment of the fetus itself but a distinct entity which subsequently gives rise to a fetus through its own powers. The viviparous conceptus differs from the egg in that it generates its fetus within the body of the mother, deriving additional nutritive material from the uterus after the generation of the fetus begins and growing together with the fetus; but in its essential characteristics it conforms entirely with the egg and can indeed be called an egg. Thus Harvey’s famous dictum that “an egg is the common primordium of all animals” does not reflect his discovery of what are now considered true eggs, where they had previously been unknown; rather, it summarizes his conclusion that in all animals—indeed, in all living things-the role of the parents in generation is indirect: they produce a fertile egg, or conceptus, or seed, which subsequently produces a new animal or plant through an innate vegetative power.⁴¹ Harvey was willing to admit the spontaneous generation of very simple animals, yet even here it is not the organism that arises spontaneously from nonliving matter but an egg or primordium that subsequently develops into the organism.

Subsequent investigation has undermined much of Harvey’s theory of generation, but his views nevertheless represented a major advance over those of his predecessors. He discredited the ancient notion that the fetus arises directly from semen and menstrual blood, although the discovery of spermatozoa shortly after his death was to restore the importance of semen in a quite different sense; he sought to eliminate the model of the separate artisan and artifact from the explanation of the formation of the fetus and thus to break down the barrier between this process and the vital activities of the mature animal; and his staunch defense of epigenesis at least provided a counterbalance to the doctrine of preformation, which came to dominate embryological theory during the later seventeenth century. Finally, the principle that all animals arise from eggs has been of great importance in the history of embryology, even though its original meaning for Harvey was very different from that which it later came to have for others.

NOTES

1. Biographical information from Keynes, The Life of William Harvey.

2. Gweneth Whitteridge, intro. to Prelectiones.

3. Pagel, “Harvey Revisited,” pt. 1, pp. 1–2.

4. Lesky, “Harvey und Aristoteles”; Pagel, Harvey’s Biological Ideas, pp. 23–47, 169–209.

5. Pagel, ibid., pp. 251–278.

6. Prelectiones, pp. 126, 142, 248-250, 256, 262, 292–294; De generatione, exs. 51, 52, 56, 57, 71; Curtis, Harvey’s Views on the Use of the Circulation, pp. 64–94, 103–138.

7. De motu cordis, ch. 1.

8. Prelectiones, pp. 264–272.

9. Realdo Colombo, De re anatomica (Venice, 1559), p. 257.

10. Gabriele Falloppio, De partibus similaribus, in Opera (Frankfurt, 1600), II, 138.

11. Prelectiones, p. 270.

12. Ibid., p. 272.

13. Ibid., intro. by Whitteridge, p. xlvii.

14. Ibid., p. 296

15. Ibid., pp. 254, 258, 272.

16. According to Robert Boyle, Harvey said, in his old age, that the contemplation of the venous valves actually led him to the circulation in the first place, but this conflicts with Harvey’s own direct testimony in De motu cordis; see Keynes, op. cit., pp. 28–30.

17. Emilio Parigiano, Nobilium exercitationum de subtilitate libri (Venice, 1623), p. 297.

18. In his later De generatione, ex. 14, Harvey refers to pp. 299–303 of this work.

19. De motu cordis, ch. 8.

20. Ibid. On this passage, see Pagel, “Harvey Revisited,” pt. 1, pp. 2–5.

21. Pagel, Harvey’s Biological Ideas, pp. 89–124.

22. Prelectiones, intro. pp. 1-li, and p. 272.

23. Curtis, Harvey’s Views, passim.

24. Prelectiones, pp. 248–250.

25. Webster, “Harvey’s De generatione,” pp. 270–274.

26. Ferrario et al, “Harvey’s Debate with Caspar Hofmann,” p. 15.

27. De generatione, exs. 51, 71; De circulatione, in Opera, 1, 132–138.

28. De motu locali, pp. 88–92, 102, 108.

29. Ibid., p. 110; see also Prelectiones, pp. 312–314; and De generatione, ex. 57.

30. De motu locali, pp. 102–104, 108, 110, 142–150.

31. Ibid., p. 110; see also pp. 40–44, 50, 94, 114.

32. Ibid., pp. 34–36, 102–104, 108, 138, 148; see also Pagel, “Harvey Revisited,” pt. 2, pp. 6–7.

33. De generatione, ex. 57; Temkin, “Glisson’s Doctrine of Irritation”; Pagel, “Harvey and Glisson on Irritability.”

34. Webster, op. cit., pp. 262–270.

35. This account of Harvey’s work on generation is based on Meyer, An Analysis of De generatione; Adelmann, The Embryological Treatises of Fabricius; and Gasking, Investigations Into Generation, in addition to De generatione itself.

36. Pagel, Harvey’s Biological Ideas, pp. 272–276.

37. De generatione, exs. 26, 62.

38. Pagel, Harvey’s Biological Ideas, pp. 233–247.

39. Pagel, “Harvey Revisited,” pt. 1, p. 11.

40. Keynes, op. cit., p. 346.

41. De generatione, ex. 62.

BIBLIOGRAPHY

I. Original Works. Harvey’s main works are Exercitatio anatomica de motu cordis et sanguinis in animalibus (Frankfurt am Main, 1628); Exercitatio anatomica de circulatione sanguinis (Cambridge, 1649); and Exercitationes de generatione animalium (London, 1651). The early trans, of all three (London, 1653) are in some respects superior to more recent versions. The standard Latin ed. is Opera omnia: A collegio medicorum Londinensi edita (London, 1766); the standard English trans, is Robert Willis, The Works of William Harvey (London, 1847), although it is at times inaccurate. For other eds. and trans., see Sir Geoffrey Keynes, A Bibliography of the Writings of Dr. William Harvey, 2nd ed. (Cambridge, 1953). Translations of the treatises on the circulation by K. J. Franklin are now available in an Everyman’s Library edition, The Circulation of The Blood and Other Writings (London-New York, 1963).

Harvey’s anatomical lecture notes have been published in facsimile, with a transcription, as Prelectiones anatomiae universalis (London, 1886); C. D. O’Malley, F. N. L. Poynter, and K. F. Russell, William Harvey Lectures on the Whole of Anatomy (Berkeley-Los Angeles, 1961), is an annotated trans.; Gweneth Whitteridge has prepared a new ed. of the Prelectiones, as well as one of “De musculis,” with intro., trans., and notes in The Anatomical Lectures of William Harvey (Edinburgh-London, 1964). She has also edited De motu locali animalium (Cambridge, 1959). The full text of Harvey’s important letter to Caspar Hofmann (1636) has been published by Ercole V. Ferrario, F. N. L. Poynter, and K. J. Franklin, “William Harvey’s Debate With Caspar Hofmann on the Circulation of the Blood,” in Journal of the History of Medicine and Allied Sciences, 15 (1960), 7–21.

II. Secondary Literature. The definitive biography is Sir Geoffrey Keynes, The Life of William Harvey (Oxford, 1966). Kenneth D. Keele, William Harvey, the Man, the Physician, and the Scientist (London, 1965), provides an excellent survey of Harvey’s work. For a more selective and detailed treatment of some of the main themes in Harvey’s work, and for comprehensive references to the Harveian literature, see Walter Pagel, William Harvey’s Biological Ideas (New York, 1967) and “William Harvey Revisited,” in History of Science, 8 (1969), 1–31; 9 (1970), 1–41. Much useful information has been gathered by H. P. Bayon, “William Harvey, Physician and Biologist, His Precursors, Opponents and Successors,” in Annals of Science, 3 (1938), 59–118, 435–456; 4 (1939), 65–106, 329–389.

On the circulation, John G. Curtis, Harvey’s Views on the Use of the Circulation of the Blood (New York, 1915), is still of fundamental importance; related themes are developed in Walter L. von Brunn, Kreislauffunktion in William Harvey’s Schriften (Berlin-New York, 1967); Gweneth Whitteridge, William Harvey and the Circulation of the Blood (London-New York, 1971), focuses on the more empirical aspects of Harvey’s work.

On sensation and locomotion, see Owsei Temkin, “The Classical Roots of Glisson’s Doctrines of Irritation,” in Bulletin of the History of Medicine, 38 (1964), 297–328; and Walter Pagel, “Harvey and Glisson on Irritability: With a Note on van Helmont,” ibid., 41 (1967), 497–514.

On generation, see Arthur W. Meyer, An Analysis of the De generatione animalium of William Harvey (Stanford, 1936); Howard B. Adelmann, The Embryological Treatises of Hieronymus Fabricius of Aquapendente (Ithaca, N.Y., 1942), esp. pp. 113–121 on Harvey’s work and its relationship to that of Fabrici; Erna Lesky, “Harvey und Aristoteles,” in Sudhoffs Archly für Geschichte der Medizin, 41 (1957), 289–316, 349–378; Elizabeth B. Gasking, Investigations Into Generation, 1651–1828 (London, 1967), esp. pp. 16–36; and C. Webster, “Harvey’s De generatione; Its Origins and Relevance to the Theory of Circulation,” in British Journal for the History of Science, 3 (1967), 262–274.

Jerome J. Bylebyl

HARVEY, WILLIAM (1578–1657)

HARVEY, WILLIAM (1578–1657), English physician and anatomist. William Harvey was born at Folkestone, on the south coast of England. He matriculated at Gonville and Caius College, Cambridge, in 1593 and studied anatomy in Padua under Girolamo Fabrizi d'Aquapendente. Harvey received his degree as doctor of medicine in 1602. Returning to England, he settled in London, where he started a medical practice. In 1607 he became a fellow of the College of Physicians and was formally appointed physician to St. Bartholomew's Hospital in 1609. In 1613 he was elected censor in the College and in 1615 Lumleian Lecturer of Surgery with the principal duties of giving a series of lectures on set texts and performing an annual public anatomy in the hall of the College. Some of the anatomical lecture notes survive and have been edited by the College of Physicians (1886); by C. D. O'Malley, F. N. L. Poynter, and K. F. Russell (1961); and by G. Whitteridge (1964).

In 1618 Harvey was appointed court physician to James I and later to Charles I (1625), and as a member of the royal entourage, he was involved in a number of political and diplomatic activities. In 1629 he attended the duke of Lennox in his travels abroad on the orders of Charles I. On several occasions (in 1633, 1639, 1640, and 1641) he was asked to accompany the king to Scotland. In 1635 he traveled with the earl of Arundel on a diplomatic mission to the Emperor Ferdinand II's court at Regensburg. After the Battle of Edgehill (1642), Harvey followed Charles I to Oxford. He remained there for three years and was made warden of Merton College in 1643. During the Civil War, his lodgings at Whitehall were plundered by Parliamentary troops, and he lost all his notes on the generation of insects and natural history. In 1646, when the city surrendered to Parliament, Harvey returned to London, where he lived in learned retirement. He died in 1657, at the age of seventy-nine.

THEORIES OF CIRCULATION

In the Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (Anatomical study on the motion of the heart and blood in animals), published in Frankfurt in 1628, Harvey announced his epoch-making discovery of the circulation of the blood. According to the old view, as it had been systematized by Galen in the second century C.E., blood originated in the liver from the assimilation and transformation of food and then ebbed and flowed through the veins in order to nourish the various parts of the body. A part of the venous blood was thought to seep through the interventricular septum of the heart (considered to be porous) and, upon arrival in the left ventricle, was supposed to undergo further elaboration as a result of being mixed with air coming from the lungs. Galen believed that the veins and the arteries were separate systems that carried fluids of different natures: thick, nutritive blood in the former, and spirituous, energizing blood in the latter. By means of a series of close arguments and experimental proofs, Harvey demonstrated that the blood was continuously and rapidly transmitted from the veins to the arteries, was driven into every part of the body in a far greater quantity than was needed for nourishment, and was finally drawn from the periphery to the heart to start the same cycle again.

A long and complex genealogy of anatomical findings and physiological speculations underlies Harvey's discovery. Realdo Colombo (1516?–1559?) discovered pulmonary circulation, but failed to put it in the wider context of systemic circulation; Andrea Cesalpino (1519–1603) caught a glimpse of the capillaries, but by circulation he meant a series of distillations occurring in the blood; Girolamo Fabrizi (1537–1619) detected the venous valves but did not understand their role in the centripetal venous flow. Unlike his predecessors, who reached only partial conclusions and remained entangled in the theoretical constraints of older accounts, Harvey managed to find an elegant and consistent solution for a whole series of interrelated problems: the correct interpretation of the systole and diastole of the heart (the former viewed as an active contraction, the latter as a passive distension), the clear demonstration of the pulmonary transit of the blood (from the right to the left ventricle by way of the pulmonary artery, the lungs, and the pulmonary vein), the understanding of the actual role of the venous valves (which serve to prevent the blood driven into the veins from being regurgitated back into the arteries). The experimental demonstration of circulation rested on the correct understanding of two key insights: the uses of ligatures of varying tightness and the calculation of the rate of blood passing through the heart at each beat.

THEORETICAL ELABORATIONS, ANATOMY, AND SPIRIT

In Exercitationes Anatomicae Duae de Circulatione Sanguinis (1649; Two anatomical exercitations on the circulation of the blood), written in response to some objections put forward by Jean Riolan, he distanced himself from René Descartes's explanation of the heartbeat. In addition, Harvey took the opportunity to define his idea of spirit as an inherent and material component of blood. In so doing, he rejected Jean Fernel's belief in the existence of transcendent and immaterial spirits governing the vital functions of the body.

The theory presented in De Motu Cordis and De Circulatione offered an alternative and revolutionary account of the anatomy and physiology of the human body. By disentangling the function of respiration from the motion of the heart and arteries and by separating the purpose of the circulation from the processes of concoction and nutrition, Harvey initiated a process of conceptual and factual reorganization in which the respiratory, digestive, and nervous apparatuses began to assume the characteristic features that they still have today. Inevitably, though, Harvey's model was also confronted with a crucial objection: why had the blood to circulate rapidly and incessantly throughout the body if nourishment of the parts was not one of the functions of that circulation and if no exchange of vital properties contained in the inhaled air took place in the lungs? The ultimate purpose of circulation and the difference between arterial and venous blood remained two unsolved points in Harvey's system.

In Exercitationes de Generatione Animalium (1651; Anatomical exercitations concerning the generation of living creatures), Harvey addressed the question of the generation of oviparous and viviparous animals. In embryology he advanced the theory that the parts of higher animals were successively formed out of the undifferentiated matter of the egg (a process he called "epigenesis"). Harvey's main concern in the treatise was the explanation of the origin and mechanism of conception. Unable to observe the initial stages of pregnancy in dissected hinds and does, he failed to understand the part played by the male's semen in fecundating the female. He argued that the process of fertilization could be compared to a transmission of vital energy at a distance.

In De Generatione Harvey also argued in favor of the preeminence of the blood, as an inherently animate matter, over the other parts of the body. His theory of epigenesis demonstrated the original nature of the blood. Its intrinsically spirituous substance confirmed the existence of a vital matter endowed with the ability to move, perceive, and respond to external stimuli. Harvey went so far as to identify the soul with the blood. His interest in the responsive nature of living matter dated back to the beginnings of his natural investigations. An unfinished treatise entitled "De Motu Locali Animalium" (On the local motion of the animals) testifies to his interest in studying the difference between voluntary and involuntary motions and the interplay of muscles, nerves, and the organs involved in locomotion and sensation.

The first to accept the circulatory model was Harvey's friend and colleague at the College of Physicians, Robert Fludd (1574–1637), who looked at the discovery of circulation as a confirmation of his speculations on the correspondence of microcosm and macrocosm. René Descartes (1596–1650) accepted Harvey's discovery of the circulation of the blood but disagreed with his explanation of the movement of the heart. Whereas Harvey maintained that the movement was the result of a vital contraction, Descartes explained it as a mechanical impulse determined by the ebullition and consequent rarefaction of the blood. Thomas Willis (1621–1675) and Richard Lower (1631–1691) refined and supplemented Harvey's circulatory model. Both mechanical anatomists like Marcello Malpighi (1628–1694) and chemical physiologists like Franciscus de la Boë (called Sylvius; 1614–1672) made Harvey's discovery an integral part of their physiological schemes. Francis Glisson (1597–1677) took the Harveian thesis of the inherently active and sentient natureoftheblood asthestartingpointforacomprehensive theory of irritability.

See also Anatomy and Physiology ; Biology ; Descartes, René ; Matter, Theories of ; Medicine ; Scientific Method .

BIBLIOGRAPHY

Primary Sources

Harvey, William. The Circulation of the Blood and Other Writings. Translated by K. J. Franklin. London, 1990.

——. The Works of William Harvey. Translated by R. Willis. London, 1847.

Secondary Sources

Bono, James. "Reform and the Languages of Renaissance Theoretical Medicine: Harvey versus Fernel." Journal of the History of Biology 23 (1990): 341–387.

Frank, Robert G. Harvey and the Oxford Physiologists: A Study of Scientific Ideas. Berkeley, 1980.

French, Roger. William Harvey's Natural Philosophy. Cambridge, U.K., 1994.

Keynes, Geoffrey. The Life of William Harvey. Oxford, 1966.

Lawrence, T. Gulielmi Harveii Opera Omnia: A Collegio Medicorum Londinensi Edita. London, 1766.

Pagel, Walter. New Light on William Harvey. Basel, 1976.

——. William Harvey's Biological Ideas. Basel, 1967.

Guido Giglioni

HARVEY, WILLIAM
(1578–1657)

William Harvey, the English doctor and anatomist, was the demonstrator of the principle of the circulation of the blood. He was born at Folkstone, Kent, and educated at King's School, Canterbury, and Gonville and Caius College, Cambridge. After taking his B.A. in 1597, he left Cambridge for Padua, where he worked with the anatomist Fabrizzi d'Acquapendente (often Latinized as Fabrizio of Aquapendente). Fabrizzi had observed the valves in the veins, although he had not understood their function; Harvey told Robert Boyle that he had developed his theory of the circulation of the blood by reflecting on the operation of these valves, perhaps while still at Padua. In 1602 Harvey graduated from Padua with a medical degree and incorporated as an M.D. of Cambridge. Taking up practice in London, he was married in 1604 to Elizabeth Browne, daughter of the physician to James I. He was elected fellow of the Royal College of Physicians in 1607, and two years later was appointed physician to St. Bartholomew's College, a position he held for thirty-four years. In 1616, when he began to lecture as Lumleian lecturer in surgery of the Royal College of Physicians (a post he assumed in 1615), he was already expounding his theory of the circulation of the blood, although he did not publish his Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (An anatomical exercise concerning the motion of the heart and the blood) until 1628. Appointed Physician Extraordinary to James I in 1618, and in 1631 to Charles I, Harvey was identified with the royalist cause during the Civil War. In 1642 his London house was ransacked by Parliamentary troops who destroyed notes and specimens. Charles I appointed him warden of Merton College, Oxford, in 1645.

After the Civil War Harvey lived a secluded life, retiring from practice and devoting himself to embryological research. Pleading age, he declined the presidency of the Royal College of Physicians in 1654, and in 1656 resigned from his Lumleian lectureship. He died at Roehampton.

There has been considerable dispute as to whether the discovery of the circulation of the blood can properly be ascribed to Harvey. As early as 1543, Andreas Vesalius had expressed doubts about the traditional Galenic account, according to which blood was made in the liver, flowed through the veins, and was then excreted, except for a small part that passed through minute channels in the septum to the right ventricle and so into the arteries. Vesalius complained that he could not find the channels through the septum. Michael Servetus (1511–1553), Andrea Cesalpino (1519–1603), and especially Matteo Realdo Colombo (1516–1559) all gave a reasonably accurate picture of the flow of blood through the lungs—the so-called lesser circulation. But none of them recognized that the entire blood supply circulated through the body.

Harvey used the comparative method. Confused by the rapidity of movements within a living human body, he dissected such cold-blooded animals as toads and shrimps, in which movement is slower. Many of his contemporaries criticized him on the ground that what was true of the lower animals had no application to man. But for Harvey, as for Aristotle, man formed part of the animal kingdom.

Harvey's great importance lies in the fact that he used the concepts of mechanics in his analysis of physiological processes. He described the working of the heart in the language of pumps; he applied mathematical calculations to show that the body could not possibly manufacture the quantity of blood which, according to Galen's theory, would have to flow through it. The fact that blood still had a quasi-mystical significance made his matter-of-fact approach particularly significant.

Harvey's work greatly influenced many early modern philosophers, including René Descartes and Thomas Hobbes (otherwise so different), who both put Harvey on a level with Galileo Galilei. They saw that Harvey had broken down the barrier between the animal and the human body, and between the processes of the body and the processes of mechanics. Thus Harvey's discovery gave empirical support to their mechanistic hypotheses. Descartes objected, however, that Harvey had not shown from first principles that the blood must necessarily circulate; he had been content to say that the heart is in fact a pump and that the blood does in fact circulate. Harvey replied to Descartes in his letters to the French anatomist Jean Riolan, who had rejected Harvey's theory. These letters were included in Exercitationes Duae Anatomicae de Circulatione Sanguinis, ad Johannem Riolanum Filium Parisiensem (Two anatomical exercises concerning the circulation of the blood, addressed to Jean Riolan Jr., of Paris; 1649).

Scientific truth, Harvey argued, is to be discovered by direct observation. "No more certain demonstration or means of gaining faith can be adduced than examination by the senses, than ocular demonstration." In this respect, Harvey compares biology favorably with astronomy. The astronomer, he suggests, argues from appearances. He cannot see what happens in an eclipse; all he actually sees is one disc sliding across another, whereas the biologist can see the heart beating in a shrimp. Observation shows us that the blood circulates, and that is enough for the biologist. This is a classic statement of the attitude of the observational biologist, in opposition to the Cartesian mathematico-physical conception of science. The Letters to Riolan also contain Harvey's criticisms of the attempt to explain physiological functioning in terms of "spirits." "Persons of limited information when they are at a loss to assign a cause for anything, very commonly reply that it is done by the spirits."

Harvey's other major work is contained in his Exercitationes Duae Anatomicae de Generatione Animalium (Two anatomical exercises concerning the generation of animals; 1651). Although this work was important in developing the view that each living thing is produced from an egg, as opposed to the doctrine of spontaneous generation, it lacks the scientific assurance of the De Motu Cordis. The fact that Harvey had to rely upon the unaided eye very much limited his achievement in this area. The first work of any consequence carried out with a microscope was done in 1660 by Marcello Malpighi, who took Harvey's theory as his point of departure.

See also Aristotle; Biology; Boyle, Robert; Descartes, René; Galileo Galilei; Hobbes, Thomas; Philosophy of Biology.

Bibliography

works by harvey

The collected Latin works of William Harvey were published in London as Opera Omnia in 1766; the earliest English texts, dating from 1653, have been reprinted, edited by Geoffrey L. Keynes (London, 1928); a complete English translation was prepared by Robert Willis for the Sydenham Society, London, in 1847. The notes Harvey prepared in 1615 for his Lumleian Lectures were published in facsimile as Praelectiones Anatomiae Universalis (London, 1886) and translated by C. D. O'Malley, F. N. L Paynter, and K. F. Russell as Lectures in the Whole of Anatomy (Berkeley, CA, 1961). The manuscript De Motu Locali Animalium (1627) was first published in Cambridge, U.K., in 1959, edited by Gweneth Whitteridge. See also De Motu Cordis, edited and translated by Kenneth James Franklin as Movement of the Heart and Blood in Animals (Oxford: Blackwell, 1957); The Circulation of the Blood, containing Harvey's reply to Jean Riolan, edited and translated by Kenneth James Franklin (London: Dent, 1963).

works on harvey

For literature on Harvey, see Geoffrey L. Keynes, A Bibliography of the Work of William Harvey (London, 1928; 2nd ed., Cambridge, U.K.: Cambridge University Press, 1953), and The Personality of William Harvey (Cambridge, U.K.: Cambridge University Press, 1949); Henry P. Bayon, "William Harvey," in Annals of Science 3 (1938): 59–118, 435–456; 4 (1939): 65–106, 329–389; Étienne Gilson, Études sur la rôle de la pensée médiévale dans la formation du système cartésien (Paris, 1951), Ch. 2; A. Rupert Hall, The Scientific Revolution, 1500–1800 (London: Longmans, Green, 1954); Louis Chauvois, William Harvey (New York, 1957); Proceedings of the Harvey Tercentenary Congress, edited by John McMichael (London, 1958); John Arthur Passmore, "William Harvey and the Philosophy of Science," Australian Journal of Philosophy 36 (2) (1958): 85–94.

John Passmore (1967)

Harvey, William William Harvey (1578–1657) was both a physician and a remarkable natural historian. His great achievement was the demonstration of the circulation of the blood, a discovery which replaced centuries of theory and speculation with knowledge firmly based on accurate observation and experiment. His work was of vital importance in illustrating the sequence of hypothesis, experiment, and conclusion which has governed all medical discovery since his time. He was the founder of modern physiology.

Harvey was born in Folkestone in Kent on 1 April 1578, the son of a yeoman, James Harvey, and his wife Joane Halke. Aged ten, in the year of the Spanish Armada, he was sent to King's School, Canterbury, and from there to Cambridge University, being admitted to Gonville and Caius College on 31 May 1593. He graduated BA in 1597 and deciding to study medicine, travelled though France and Germany to Padua, where Galileo was then teaching. There is no evidence that Harvey ever met Galileo, nor of whether he believed in the heliocentric view of the universe. His own mentor was the great anatomist, Fabricius of Aquapendente, who maintained the traditions of Vesalius at Padua. Harvey graduated MD in Padua on 25 April 1602 and returned to London, taking his Cambridge MD in that same year. Two years later he married Elizabeth Browne, daughter of Dr Lancelot Browne, onetime physician to Queen Elizabeth. In 1607, he became a Fellow of the College of Physicians and in 1609 began his long association with St Bartholomew's Hospital, on appointment as assistant physician.

In 1615, Harvey was elected Lumleian Lecturer at the College of Physicians, and he delivered his first lectures in April 1616. The notes he used for these lectures not only illustrate his wide reading and knowledge of the classics, but also reveal some of the ideas that led him to the discovery of the circulation of the blood. For many years he gave the Lumleian lectures annually at the College.

His position as a physician was increasingly recognized in wider circles through these years. In 1618 he became physician to James I, initiating a link with the Royal family that persisted throughout his long life. In 1630, at the behest of King Charles I, he accompanied the Duke of Lennox on a European tour and two years later travelled with the King to Scotland. In the years before the Civil War he was in London, but he went to Oxford in attendance on the King in 1642. There, on 7 December, he was made MD of the University. He pursued his anatomical studies and dissections at Merton College. He was at the battle of Edgehill and is said to have had charge of the Prince of Wales and the Duke of York during the action. After the surrender of Oxford in 1646, he returned to London and there continued his scientific studies. He was active in the affairs of the College of Physicians, being elected President in 1654, an honour he declined because of his increasing years, being 76 years old. In that same year he donated his library to the College. He died on 3 June 1657 and was interred at Hempstead.

Harvey's monumental work De Motu Cordis was published in 1628. In his dedication to King Charles I, he likened the position of the monarch in his kingdom with that of the heart within the body. Until that time, medical opinion was governed by the views of the second century writer, Galen, whose works had gained a position among learned physicians that was almost akin to holy writ. The Galenical view was that the blood was formed in the liver from nutrients derived from the intestine. It passed from there to the heart, where it was imbued with ‘vital spirits’, and then traversed the septum (which divides the right and left sides of the heart) through invisible ‘pores’. The different functions of the veins and arteries were unknown and the blood was considered to ebb and flow in the veins to reach the tissues of the body.

Harvey's observations clearly showed the Galenical view to be erroneous. Using experiments in animals such as the snake, he demonstrated that the blood passed from the veins to the right side of the heart (the right ventricle), that the supposed pores in the septum of the heart did not exist, and that the right ventricle propelled the blood into the lungs. It then returned to the left side of the heart. The left ventricle was thicker and more powerful than its counterpart on the right side, because it pumped blood not just through the lungs but throughout the entire body. Harvey clearly demonstrated that blood in the arteries was always carried away from the heart, and how the valves in the veins, originally described by his teacher, Fabricius, ensured that the venous blood always flowed towards the heart. He calculated how much blood might be propelled from the heart with each heart beat and showed there was no likelihood that the liver could synthesize sufficient blood to enter the heart as proposed by the Galenists. From ingenious but classically simple experiments and observations, Harvey concluded that the only explanation for the heart's action must be that a defined amount of blood constantly circulated throughout the body.

Harvey's discovery, comparable to the anatomical studies of Vesalius, was of great importance in destroying the influence of Galen, whose dogmatic assertions had by then become pernicious. It was perhaps natural that so novel and original a discovery would generate controversy. On the continent, Leyden was the first university to accept Harvey's conclusions; in many other schools, particularly in Paris, it was a further half century before Harvey's work was fully appreciated. So important was his work, however, that by the beginning of the eighteenth century the great Dutch teacher of medicine in Leyden, Hermann Boerhaave, stated that nothing that had been written before Harvey was any longer worthy of consideration.

Harvey was interested in many other aspects of comparative anatomy and physiology, for example the problem of reproduction, then poorly understood. But his discovery of the circulation of the blood remains his lasting memorial. His death in 1657 preceded by three years the foundation, by Charles II, of the Royal Society of London. It was, however, in large part due to the influence of William Harvey that the Society chose as its motto ‘Nullius in verba’

C. C. Booth

Bibliography

Keynes, G. (1978). The life of William Harvey. Clarendon Press, Oxford.
Whitteridge, G. (1976). William Harvey: an anatomical disputation concerning the movement of the heart and blood in living creatures. Blackwell Scientific Publications, Oxford, London.

Harvey, William

English physician and physiologist
1578–1657

William Harvey was an English physician, a pioneer in the study of blood circulation and embryology, and the founder of experimental physiology. Educated in Cambridge, England, and Padua, Italy, he practiced medicine in London and was court physician to King James I and King Charles I.

The Roman physician Galen (129–c. 199 C.E.) had argued that the liver received food from the small intestine and converted it to blood, the heart pumped this blood to the other organs, and those organs consumed it. Harvey, refusing to accept this, measured the amount of blood pumped by the hearts of snakes and other animals. He concluded that (1) the heart pumps more blood in half an hour than there is in the entire body; (2) animals do not consume enough food to account for so much blood; and (3) the blood must be continually recirculated around the body, since the planets orbit the Sun and (he believed) the human body is modeled after the solar system. So for a mixture of scientific and superstitious reasons, Harvey correctly deduced that after blood leaves the heart it returns there rather than being consumed. He predicted that there must be a connection between the arteries and veins so blood could get back to the heart. Such connections, the capillaries, were first seen by Antony van Leeuwenhoek and Marcello Malpighi after Harvey's death.

Harvey published his conclusions in the book Anatomical Studies on the Motion of the Heart and Blood in Animals (a translation of its Latin title) in 1628. Harvey's contemporaries were so wedded to the ancient beliefs of Aristotle and Galen, however, that they ridiculed his conclusions. How could the blood serve any purpose, they argued, if the organs did not consume it? Harvey's reputation survived this skepticism, however, and he went on to do important work in embryology.

Harvey was forced to flee for his life in 1642, and his home was ransacked and his records destroyed in a rebellion against the British monarchy that ended with the beheading of his patron, King Charles. Depressed by this turn of events, Harvey gave up his medical practice and retired to the countryside. Nevertheless, at the urging of friends, he resumed work. Harvey rejected the belief that animals can arise from decaying flesh, and argued that every animal, including humans, arises from the union of sperm and egg. In 1651 he published this theory of animal development, with a detailed account of the embryology of the chick, as Studies on the Generation of Animals. The frontispiece of his book bore the inscription ex ovo omnia —everything [comes] from an egg.

Harvey died of a stroke in 1657, honored by his country and wealthy from the income on his books.

see also Blood Vessels; Circulatory Systems; Heart and Circulation; History of Medicine

Kenneth S. Saladin

Bibliography

Durant, Will, and Ariel Durant. The Story of Civilization, Vol. VII. New York: Simon & Schuster, 1961.

Marcus, Rebecca. William Harvey, Trailblazer of Scientific Medicine. New York: Franklin Watts, 1962.

Moore, John A. Science as a Way of Knowing. Cambridge, MA: Harvard University Press, 1993.