William Harvey: Exercitationes de Generatione Animalium

William Harvey

William Harvey: Exercitationes de Generatione Animalium, 1651

The most important book on the subject to appear during the 17th century

William Harvey:

Exercitationes de | Generatione Animalium. | Quibus accedunt quædam | De Partu: de Membranis | ac humoribus Uteri: | & de Conceptione. | Autore | Guilielmo Harveo | Anglo, in Collegio Medico-|rum Londinenſium Anato-|mes & Chirurgiæ Profeſſore | Editio noviſsima a mendis repurgata.

Amsterdam: „Apud Ioannem Ravesteynium“, 1651.

Duodecimo. 131 × 76 mm. [24], 388, [3], [1 weiße] Seiten. - Lagensignaturen: (*)12, (*)(*)2, A-Q12, R4. Mit gestochenem Titel: „The engraving is a partial copy of those in the Elzevir and Jansson editions of the same year. Jove is seated on a pedestal with him on his a curtain overhanging him on his right and with three pillars beyond him on his left. Between the pillars is seen a distant landscape and a crocodile. (...) On the ground on either side of the pedestral are birds on baskets of eggs (...)“ (Keynes).

Handgefertigter Pergamenteinband der Zeit auf drei durchgezogenen Pergamentbünden, umgeschlagene Vorderkanten, handgestochene grüne Kapitale, Rotschnitt.

Einer von vier Amsterdamer Drucken (Keyney 35-38), die im selben Jahr wie die Londoner Erstausgabe erschienen. Harveys zweites epochemachendes Werk, „clearly a work of very great importance“ (Keynes, p. 48): „Harvey hatte mit seinem anderen Buche weniger Erfolg, obwohl es ebenso zuverlässig auf Experimente gegründet war. Es ist bemerkenswert, mit welcher Entschiedenheit er darauf bestand, daß alle lebendige Materie aus dem Ei entstehe, so daß keine spontane Zeugung vor sich gehen könne“ (Carter/Muir S. 250).
 „The most important book on the subject to appear during the 17th century (...) Harvey considered this to be the culminating work of his life, and more significant than ’De motu cordis’“ (Garrison/Morton). „Even if Harvey had not discovered the circulation of the blood, his remarkable work on embryology would have placed him in the front ranks of biological scientists. (...) He disbelieved the previously-held doctrine of ‚preformation‘ of the fetus, maintaining instead that it proceeds from the ovum by gradual building up of its parts“ (Heirs of Hippocrates, p. 134).

Keynes 38 – Krivatsy 5346 – Wellcome III,220 – cf. Heirs of Hippocrates 271-273 – cf. PMM 127. – Bibliographienelektronisches Faksimile der Elzevier-Ausgabe gleichen Jahres.



Harvey, William (1578–1657), English physician, the discoverer of the circulation of the blood, was the eldest son of Thomas Harvey, a prosperous Kentish yeoman, and was born at Folkestone on the 1st of April 1578. After passing through the grammar school of Canterbury, on the 31st of May 1593, having just entered his sixteenth year, he became a pensioner of Caius College, Cambridge, at nineteen he took his B.A. degree, and soon after, having chosen the profession of medicine, he went to study at Padua under H. Fabricius and Julius Casserius. At the age of twenty-four Harvey became doctor of medicine, in April 1602. Returning to England in the first year of James I., he settled in London; and two years later he married the daughter of Dr Lancelot Browne, who had been physician to Queen Elizabeth. In the same year he became a candidate of the Royal College of Physicians, and was duly admitted a fellow (June 1607). In 1609 he obtained the reversion of the post of physician to St Bartholomew's hospital. His application was supported by the king himself and by Dr Henry Atkins (1558–1635), the president of the college, and on the death of Dr Wilkinson in the course of the same year he succeeded to the post. He was thrice censor of the college, and in 1615 was appointed Lumleian lecturer.

In 1616 he began his course of lectures, and first brought forward his views upon the movements of the heart and blood. Meantime his practice increased, and he had the lord chancellor, Francis Bacon, and the earl of Arundel among his patients. In 1618 he was appointed physician extraordinary to James I., and on the next vacancy physician in ordinary to his successor. In 1628, the year of the publication of the Exercitatio anatomica de motu cordis et sanguinis, he was elected treasurer of the College of Physicians, but at the end of the following year he resigned the office, in order, by command of Charles I., to accompany the young duke of Lennox (James Stuart, afterwards duke of Richmond) on his travels. He appears to have visited Italy, and returned in 1632. Four years later he accompanied the earl of Arundel on his embassy to the emperor Ferdinand II. He was eager in collecting objects of natural history, sometimes causing the earl anxiety for his safety by his excursions in a country infested by robbers in consequence of the Thirty Years' War. In a letter written on this journey, he says: "By the ​way we could scarce see a dogg, crow, kite, raven, or any bird, or anything to anatomise; only sum few miserable people, the reliques of the war and the plague, whom famine had made anatomies before I came.” Having returned to his practice in London at the close of the year 1636, he accompanied Charles I. in one of his journeys to Scotland (1639 or 1641). While at Edinburgh he visited the Bass Rock; he minutely describes its abundant population of sea-fowl in his treatise De generatione, and incidentally speaks of the account then credited of the solan goose growing on trees as a fable. He was in attendance on the king at the battle of Edgehill (October 1642), where he withdrew under a hedge with the prince of Wales and the duke of York (then boys of twelve and ten years old), “and took out of his pocket a book and read. But he had not read very long before a bullet of a great gun grazed on the ground near him, which made him remove his station,” as he afterwards told John Aubrey. After the indecisive battle, Harvey followed Charles I. to Oxford, “where,” writes the same gossiping narrator, “I first saw him, but was then too young to be acquainted with so great a doctor. I remember he came several times to our college (Trinity) to George Bathurst, B.D. who had a hen to hatch eggs in his chamber, which they opened daily to see the progress and way of generation.” In Oxford he remained three years, and there was some chance of his being superseded in his office at St Bartholomew’s hospital, “because he hath withdrawn himself from his charge, and is retired to the party in arms against the Parliament.” It was no doubt at this time that his lodgings at Whitehall were searched, and not only the furniture seized but also invaluable manuscripts and anatomical preparations.[1]

While with the king at Oxford he was made warden of Merton College, but a year later, in 1646, that city surrendered to Fairfax, and Harvey returned to London. He was now sixty-eight years old, and, having resigned his appointments and relinquished the cares of practice, lived in learned retirement with one or other of his brothers. It was in his brother Daniel’s house at Combe that Dr (afterwards Sir George) Ent, a faithful friend and disciple (1604–1689), visited him in 1650. “I found him,” he says, “with a cheerful and sprightly countenance investigating, like Democritus, the nature of things. Asking if all were well with him—‘How can that be,’ he replied, ‘when the state is so agitated with storms and I myself am yet in the open sea? And indeed, were not my mind solaced by my studies and the recollection of the observations I have formerly made, there is nothing which should make me desirous of a longer continuance. But thus employed, this obscure life and vacation from public cares which would disgust other minds is the medicine of mine.’” The work on which he had been chiefly engaged at Oxford, and indeed since the publication of his treatise on the circulation in 1628, was an investigation into the recondite but deeply interesting subject of generation. Charles I. had been an enlightened patron of Harvey’s studies, had put the royal deer parks at Windsor and Hampton Court at his disposal, and had watched his demonstration of the growth of the chick with no less interest than the movements of the living heart. Harvey had now collected a large number of observations, though he would probably have delayed their publication. But Ent succeeded in obtaining the manuscripts, with authority to print them or not as he should find them. “I went from him,” he says, “like another Jason in possession of the golden fleece, and when I came home and perused the pieces singly, I was amazed that so vast a treasure should have been so long hidden.” The result was the publication of the Exercitationes de generatione (1651).

This was the last of Harvey’s labours. He had now reached his seventy-third year. His theory of the circulation had been opposed and defended, and was now generally accepted by the most eminent anatomists both in his own country and abroad. He was known and honoured throughout Europe, and his own college (Caius) voted a statue in his honour (1652) viro monumentis suis immortali. In 1654 he was elected to the highest post in his profession, that of president of the college; but the following day he met the assembled fellows, and, declining the honour for himself on account of the infirmities of age, recommended the re-election of the late president Dr Francis Prujean (1593–1666). He accepted, however, the office of consiliarius, which he again held in the two following years. He had already enriched the college with other gifts besides the honour of his name. He had raised for them “a noble building of Roman architecture (rustic work with Corinthian pilasters), comprising a great parlour or conversation room below and a library above”; he had furnished the library with books, and filled the museum with “simples and rarities,” as well as with specimens of instruments used in the surgical and obstetric branches of medicine. At last he determined to give to his beloved college his paternal estate at Burmarsh in Kent. His wife had died some years before, his brothers were wealthy men, and he was childless, so that he was defrauding no heir when, in July 1656, he made the transfer of this property, then valued at £56 per annum, with provision for a salary to the college librarian and for the endowment of an annual oration, which is still given on the anniversary of the day. The orator, so Harvey orders in his deed of gift, is to exhort the fellows of the college “to search out and study the secrets of nature by way of experiment, and also for the honour of the profession to continue mutual love and affection among themselves.”

Harvey, like his contemporary and great successor Thomas Sydenham, was long afflicted with gout, but he preserved his activity of mind to an advanced age. In his eightieth year, on the 3rd of June 1657, he was attacked by paralysis, and though deprived of speech was able to send for his nephews and distribute his watch, ring, and other personal trinkets among them. He died the same evening, “the palsy giving him an easy passport,” and was buried with great honour in his brother Eliab’s vault at Hempstead in Essex, annorum et famae satur. In 1883 the lead coffin containing his remains was enclosed in a marble sarcophagus and moved to the Harvey chapel within the church.

John Aubrey, to whom we owe most of the minor particulars about Harvey which have been preserved, says: “In person he was not tall, but of the lowest stature, round faced, olivaster complexion, little eyes, round, very black, full of spirits; his hair black as a raven, but quite white twenty years before he died.” The best portrait of him extant is by Cornelius Jansen in the library of the College of Physicians, one of those rescued from the great fire, which destroyed their original hall in 1666. It has been often engraved, and is prefixed to the fine edition of his works published in 1766.

Harvey’s Work on the Circulation.—In estimating the character and value of the discovery announced in the Exercitatio de motu cordis et sanguinis, it is necessary to bear in mind the previous state of knowledge on the subject. Aristotle taught that in man and the higher animals the blood was elaborated from the food in the liver, thence carried to the heart, and sent by it through the veins over the body. His successors of the Alexandrian school of medicine, Erasistratus and Herophilus, further elaborated his system, and taught that, while the veins carried blood from the heart to the members, the arteries carried a subtle kind of air or spirit. For the practical physician only two changes had been made in this theory of the circulation between the Christian era and the 16th century. Galen had discovered that the arteries were not, as their name implies, merely air-pipes, but that they contained blood as well as vital air or spirit. And it had been gradually ascertained that the nerves (νεῦρα) which ​arose from the brain and conveyed “animal spirits” to the body were different from the tendons or sinews (νεῦρα) which attach muscles to bones. First, then, the physicians of the time of Thomas Linacre knew that the blood is not stagnant in the body. So did Shakespeare and Homer, and every augur who inspected the entrails of a victim, and every village barber who breathed a vein. Plato even uses the expression to τὸ αἷμα κατὰ πάντα τὰ μέλη σφοδρῶς περιφέρεσθαι. But no one had a conception of a continuous stream returning to its source (a circulation in the true sense of the word) either in the system or in the lungs. If they used the word circulatio, as did Caesalpinus,[2] it was as vaguely as the French policeman cries “Circulez.” The movements of the blood were in fact thought to be slow and irregular in direction as well as in speed, like the “circulation” of air in a house, or the circulation of a crowd in the streets of a city. Secondly, they supposed that one kind of blood flowed from the liver to the right ventricle of the heart, and thence to the lungs and the general system by the veins, and that another kind flowed from the left ventricle to the lungs and general system by the arteries. Thirdly, they supposed that the septum of the heart was pervious and allowed blood to pass directly from the right to the left side. Fourthly, they had no conception of the functions of the heart as the motor power of the movement of the blood. They doubted whether its substance was muscular; they supposed its pulsation to be due to expansion of the spirits it contained; they believed the only dynamic effect which it had on the blood to be sucking it in during its active diastole, and they supposed the chief use of its constant movements to be the due mixture of blood and spirits.

Of the great anatomists of the 16th century, Sylvius (In Hipp. et Gal. phys. partem anatom. isagoge) described the valves of the veins; Vesalius (De humani corporis fabrica, 1542) ascertained that the septum between the right and left ventricles is complete, though he could not bring himself to deny the invisible pores which Galen’s system demanded. Servetus, in his Christianismi restitutio (1553), goes somewhat farther than his fellow-student Vesalius, and says: “Paries ille medius non est aptus ad communicationem et elaborationem illam; licet aliquid resudare possit”; and, from this anatomical fact and the large size of the pulmonary arteries he concludes that there is a communication in the lungs by which blood passes from the pulmonary artery to the pulmonary vein: “Eodem artificio quo in hepate fit transfusio a vena porta ad venam cavam propter sanguinem, fit etiam in pulmone transfusio a vena arteriosa ad arteriam venosam propter spiritum.” The natural spirit of the left side and the vital spirit of the right side of the heart were therefore, he concluded, practically the same, and hence two instead of three distinct spiritus should be admitted. It seems doubtful whether even Servetus rightly conceived of the entire mass of the blood passing through the pulmonary artery and the lungs. The transference of the spiritus naturalis to the lungs, and its return to the left ventricle as spiritus vitalis, was the function which he regarded as important. Indeed a true conception of the lesser circulation as a transference of the whole blood of the right side to the left was impossible until the corresponding transference in the greater or systematic circulation was discovered. Servetus, however, was the true predecessor of Harvey in physiology, and his claims to that honour are perfectly authentic and universally admitted.[3] The way then to Harvey’s great work had been paved by the discovery of the valves in the veins, and by that of the lesser circulation—the former due to Sylvius and Fabricius, the latter to Servetus—but the significance of the valves was unsuspected and the fact of even the pulmonary circulation was not generally admitted in its full meaning.

In his treatise Harvey proves (1) that it is the contraction, not the dilatation, of the heart which coincides with the pulse, and that the ventricles as true muscular sacs squeeze the blood which they contain into the aorta and pulmonary artery; (2) that the pulse is not produced by the arteries enlarging and so filling, but by the arteries being filled with blood and so enlarging; (3) that there are no pores in the septum of the heart, so that the whole blood in the right ventricle is sent to the lungs and round by the pulmonary veins to the left ventricle, and also that the whole blood in the left ventricle is again sent into the arteries, round by the smaller veins into the venae cavae, and by them to the right ventricle again—thus making a complete “circulation”; (4) that the blood in the arteries and that in the veins is the same blood; (5) that the action of the right and left sides of the heart, auricles, ventricles and valves, is the same, the mechanism in both being for reception and propulsion of liquid and not of air, since the blood on the right side, though mixed with air, is still blood; (6) that the blood sent through the arteries to the tissues is not all used, but that most of it runs through into the veins; (7) that there is no to and fro undulation in the veins, but a constant stream from the distant parts towards the heart; (8) that the dynamical starting-point of the blood is the heart and not the liver.

The method by which Harvey arrived at his complete and almost faultless solution of the most fundamental and difficult problem in physiology has been often discussed, and is well worthy of attention. He begins his treatise by pointing out the many inconsistencies and defects in the Galenical theory, quoting the writings of Galen himself, of Fabricius, Columbus and others, with great respect, but with unflinching criticism. For, in his own noble language, wise men must learn anatomy, not from the decrees of philosophers, but from the fabric of nature herself, “nec ita in verba jurare antiquitatis magistrae, ut veritatem amicam in apertis relinquant, et in conspectu omnium deserant.” He had, as we know, not only furnished himself with all the knowledge that books and the instructions of the best anatomists of Italy could give, but, by a long series of dissections, had gained a far more complete knowledge of the comparative anatomy of the heart and vessels than any contemporary—we may almost say than any successor—until the times of John Hunter and J. F. Meckel. Thus equipped, he tells us that he began his investigations into the movements of the heart and blood by looking at them—i.e. by seeing their action in living animals. After a modest preface, he heads his first chapter ​“Ex vivorum dissectione, qualis sit cordis motus.” He minutely describes what he saw and handled in dogs, pigs, serpents, frogs and fishes, and even in slugs, oysters, lobsters and insects, in the transparent minima squilla, “quae Anglice dicitur a shrimp,” and lastly in the chick while still in the shell. In these investigations he used a perspicillum or simple lens. He particularly describes his observations and experiments on the ventricles, the auricles, the arteries and the veins. He shows how the arrangement of the vessels in the foetus supports his theory. He adduces facts observed in disease as well as in health to prove the rapidity of the circulation. He explains how the mechanism of the valves in the veins is adapted, not, as Fabricius believed, to moderate the flow of blood from the heart, but to favour its flow to the heart. He estimates the capacity of each ventricle, and reckons the rate at which the whole mass of blood passes through it. He elaborately and clearly demonstrates the effect of obstruction of the blood-stream in arteries or in veins, by the forceps in the case of a snake, by a ligature on the arm of a man, and illustrates his argument by figures. He then sums up his conclusion thus: “Circulari quodam motu, in circuitu, agitari in animalibus sanguinem, et esse in perpetuo motu; et hanc esse actionem sive functionem cordis quam pulsu peragit; et omnino motus et pulsus cordis causam unam esse.” Lastly, in the 15th, 16th and 17th chapters, he adds certain confirmatory evidence, as the effect of position on the circulation, the absorption of animal poisons and of medicines applied externally, the muscular structure of the heart and the necessary working of its valves. The whole treatise, which occupies only 67 pages of large print in the quarto edition of 1766, is a model of accurate observation, patient accumulation of facts, ingenious experimentation, bold yet cautious hypothesis and logical deduction.

In one point only was the demonstration of the circulation incomplete. Harvey could not discover the capillary channels by which the blood passes from the arteries to the veins. This gap in the circulation was supplied several years later by the great anatomist Marcello Malpighi, who in 1661 saw in the lungs of a frog, by the newly invented microscope, how the blood passes from the one set of vessels to the other. Harvey saw all that could be seen by the unaided eye in his observations on living animals; Malpighi, four years after Harvey’s death, by another observation on a living animal, completed the splendid chain of evidence. If this detracts from Harvey’s merit it leaves Servetus no merit at all. But in fact the existence of the channels first seen by Malpighi was as clearly pointed to by Harvey’s reasoning as the existence of Neptune by the calculations of Leverrier and of Adams.

Harvey himself and all his contemporaries were well aware of the novelty and importance of his theory. He says in the admirable letter to Dr Argent, president of the College of Physicians, which follows the dedication of his treatise to Charles I., that he should not have ventured to publish “a book which alone asserts that the blood pursues its course and flows back again by a new path, contrary to the received doctrine taught so many ages by innumerable learned and illustrious men,” if he had not set forth his theory for more than nine years in his college lectures, gradually brought it to perfection, and convinced his colleagues by actual demonstrations of the truth of what he advanced. He anticipates opposition, and even obloquy or loss, from the novelty of his views. These anticipations, however, the event proved to have been groundless. If we are to credit Aubrey indeed, he found that after the publication of the De motu “he fell mightily in his practice; ’twas believed by the vulgar that he was crackbrained, and all the physicians were against him.” But the last assertion is demonstrably untrue; and if apothecaries and patients ever forsook him, they must soon have returned, for Harvey left a handsome fortune. By his own profession the book was received as it deserved. So novel a doctrine was not to be accepted without due inquiry, but his colleagues had heard his lectures and seen his demonstrations for years; they were already convinced of the truth of his theory, urged its publication, continued him in his lectureship, and paid him every honour in their power. In other countries the book was widely read and much canvassed. Few accepted the new theory; but no one dreamt of claiming the honour of it for himself, nor for several years did any one pretend that it could be found in the works of previous authors. The first attack on it was a feeble tract by one James Primerose, a pupil of Jean Riolan (Exerc. et animadv. in libr. Harvei de motu cord. et sang., 1630). Five years later Parisanus, an Italian physician, published his Lapis Lydius de motu cord. et sang. (Venice, 1635), a still more bulky and futile performance. Primerose’s attacks were “imbellia pleraque” and “sine ictu”; that of Parisanus “in quamplurimis turpius,” according to the contemporary judgment of Johann Vessling. Their dulness has protected them from further censure. Caspar Hoffmann, professor at Nuremberg, while admitting the truth of the lesser circulation in the full Harveian sense, denied the rest of the new doctrine. To him the English anatomist replied in a short letter, still extant, with great consideration yet with modest dignity, beseeching him to convince himself by actual inspection of the truth of the facts in question. He concludes: “I accept your censure in the candid and friendly spirit in which you say you wrote it; do you also the same to me, now that I have answered you in the same spirit.” This letter is dated May 1636, and in that year Harvey passed through Nuremberg with the earl of Arundel, and visited Hoffmann. But he failed to convince him; “nec tamen valuit Harveius vel coram,” writes P. M. Schlegel, who, however, afterwards succeeded in persuading the obstinate old Galenist to soften his opposition to the new doctrine, and thinks that his complete conversion might have been effected if he had but lived a little longer—“nec dubito quin concessisset tandem in nostra castra.” While in Italy the following year Harvey visited his old university of Padua, and demonstrated his views to Professor Vessling. A few months later this excellent anatomist wrote him a courteous and sensible letter, with certain objections to the new theory. The answer to this has not been preserved, but it convinced his candid opponent, who admitted the truth of the circulation in a second letter (both were published in 1640), and afterwards told a friend, “Harveium nostrum si audis, agnosces coelestem sanguinis et spiritus ingressum ex arteriis per venas in dextrum cordis sinum.” Meanwhile a greater convert, R. Descartes, in his Discours sur la méthode (1637) had announced his adhesion to the new doctrine, and refers to “the English physician to whom belongs the honour of having first shown that the course of the blood in the body is nothing less than a kind of perpetual movement in a circle.” J. Walaeus of Leyden, H. Regius of Utrecht and Schlegel of Hamburg successively adopted the new physiology. Of these professors, Regius was mauled by the pertinacious Primerose and mauled him in return (Spongia qua eluuntur sordes quae Jac. Primirosius, &c., and Antidotum adv. Spongiam venenatam Henr. Regii). Descartes afterwards repeated Harvey’s vivisections, and, more convinced than ever, demolished Professor V. F. Plempius of Louvain, who had written on the other side. George Ent also published an Apologia pro circulatione sanguinis in answer to Parisanus.

At last Jean Riolan ventured to publish his Enchiridium anatomicum (1648), in which he attacks Harvey’s theory, and proposes one of his own. Riolan had accompanied the queen dowager of France (Maria de’ Medici) on a visit to her daughter at Whitehall, and had there met Harvey and discussed his theory. He was, in the opinion of the judicious Haller, “vir asper et in nuperos suosque coaevos immitis ac nemini parcens, nimis avidus suarum laudum praeco, et se ipso fatente anatomicorum princeps.” Harvey replied to the Enchiridium with perfectly courteous language and perfectly conclusive arguments, in two letters De circulatione sanguinis, which were published at Cambridge in 1649, and are still well worth reading. He speaks here of the “circuitus sanguinis a me inventus.” Riolan was unconvinced, but lived to see another professor of anatomy appointed in his own university who taught Harvey’s doctrines. Even in Italy, Trullius, professor of anatomy at Rome, expounded the new doctrine in 1651. But the most illustrious converts were Jean Pecquet of Dieppe, the discoverer of the thoracic duct, and of the true course of the lacteal vessels, and Thomas Bartholinus of Copenhagen, in his Anatome ex omnium veterum recentiorumque observationibus, imprimis institutionibus beati mei parentis Caspari Bartholini, ad circulationem Harveianam et vasa lymphatica renovata (Leiden, 1651). At last Plempius also retracted all his objections; for, as he candidly stated, “having opened the bodies of a few living dogs, I find that all Harvey’s statements are perfectly true.” Hobbes of Malmesbury could thus say in the preface to his Elementa philosophiae that his friend Harvey, “solus quod sciam, doctrinam novam superata invidia vivens stabilivit.”

It has been made a reproach to Harvey that he failed to appreciate the importance of the discoveries of the lacteal and lymphatic vessels by G. Aselli, J. Pecquet and C. Bartholinus. In three letters on the subject, one to Dr R. Morison of Paris (1652) and two to Dr Horst of Darmstadt (1655), a correspondent of Bartholin’s, he discusses these observations, and shows himself unconvinced of their accuracy. He writes, however, with great moderation and reasonableness, and excuses himself from investigating the subject further on the score of the infirmities of age; he was then above seventy-four. The following quotation shows the spirit of these letters: “Laudo equidem summopere Pecqueti aliorumque in indaganda veritate industriam singularem, nec dubito quin multa adhuc in Democriti puteo abscondita sint, a venturi saeculi indefatigabili diligentia expromenda.” Bartholin, though reasonably disappointed in not having Harvey’s concurrence, speaks of him with the utmost respect, and generously says that the glory of discovering the movements of the heart and of the blood was enough for one man.

Harvey’s Work on Generation. — We have seen how Dr. Ent persuaded his friend to publish this book in 1651. It is between five and six times as long as the Exerc. de motu cord. et sang., and is followed by excursus De partu, De uteri membranis, De conceptione; but, though the fruit of as patient and extensive observations, its value is far inferior. The subject was far more abstruse, and in fact inaccessible to proper investigation without the aid of the microscope. And the field was almost untrodden since the days of Aristotle. Fabricius, Harvey’s master, in his work De formatione ovi et pulli (1621), had alone preceded him in modern times. Moreover, the seventy-two chapters which form the book lack the co-ordination so conspicuous in the earlier treatise, and some of them seem almost like detached chapters of a system which was never completed or finally revised.

Aristotle had believed that the male parent furnished the body of the future embryo, while the female only nourished and formed the seed; this is in fact the theory on which, in the Eumenides of Aeschylus, Apollo obtains the acquittal of Orestes. Galen taught almost as erroneously that each parent contributes seeds, the union of which produced the young animal. Harvey, after speaking with due honour of Aristotle and Fabricius, begins rightly “ab ovo”; for, as he remarks, “eggs cost little and are always and everywhere to be had,” and moreover “almost all animals, even those which bring forth their young alive, and man himself, are produced from eggs” (“omnia omnino animalia, etiam vivipara, atque hominem adeo ipsum, ex ovo progigni”). This dictum, usually quoted as “omne vivurn ex ovo,” would alone stamp this work as worthy of the discoverer of the circulation of the blood, but it was a prevision of genius, and was not proved to be a fact until K. E. von Baer discovered the mammalian ovum in 1827. Harvey proceeds with a careful anatomical description of the ovary and oviduct of the hen, describes the new-laid egg, and then gives an account of the appearance seen on the successive days of incubation, from the 1st to the 6th, the 10th and the 14th, and lastly describes the process of hatching. He then comments upon and corrects the opinions of Aristotle and Fabricius, declares against spontaneous generation (though in one passage he seems to admit the current doctrine of production of worms by putrefaction as an exception), proves that there is no semen foemineum, that the chalazae of the hen’s eggs are not the semen galli, and that both parents contribute to the formation of the egg. He describes accurately the first appearance of the ovarian ova as mere specks, their assumption of yelk and afterwards of albumen. In chapter xlv. he describes two methods of production of the embryo from the ovum: one is metamorphosis, or the direct transformation of pre-existing material, as a worm from an egg, or a butterfly from an aurelia (chrysalis); the other is epigenesis, or development with addition of parts, the true generation observed in all higher animals. Chapters xlvi.-l. are devoted to the abstruse question of the efficient cause of generation, which, after much discussion of the opinions of Aristotle and of Sennertius, Harvey refers to the action of both parents as the efficient instruments of the first great cause.[4] He then goes on to describe the order in which the several parts appear in the chick. He states that the punctum saliens or foetal heart is the first organ to be seen, and explains that the nutrition of the chick is not only effected by yelk conveyed directly into the midgut, as Aristotle taught, but also by absorption from yelk and white by the umbilical (omphalomeseraic) veins; on the fourth day of incubation appear two masses (which he oddly names vermiculus), one of which develops into three vesicles, to form the cerebrum, cerebellum and eyes, the other into the breastbone and thorax; on the sixth or seventh day come the viscera, and lastly, the feathers and other external parts. Harvey points out how nearly this order of development in the chick agrees with what he had observed in mammalian and particularly in human embryos. He notes the bifid apex of the foetal heart in man and the equal thickness of the ventricles, the soft cartilages which represent the future bones, the large amount of liquor amnii and absence of placenta which characterize the foetus in the third month; in the fourth the position of the testes in the abdomen, and the uterus with its Fallopian tubes resembling the uterus bicornis of the sheep; the large thymus; the caecum, small as in the adult, not forming a second stomach as in the pig, the horse and the hare; the lobulated kidneys, like those of the seal (“vitulo,” sc. marino) and porpoise, and the large suprarenal veins, not much smaller than those of the kidneys (li.-lvi). He failed, however, to trace the connexion of the urachus with the bladder. In the following chapters (lxiii.-lxxii.) he describes the process of generation in the fallow deer or the roe. After again insisting that all animals arise from ova, that a “conception” is an internal egg and an egg an extruded conception, he goes on to describe the uterus of the doe, the process of impregnation, and the subsequent development of the foetus and its membranes, the punctum saliens, the cotyledons of the placenta, and the “uterine milk,” to which Sir William Turner recalled attention in later years. The treatise concludes with detached notes on the placenta, parturition and allied subjects.

Harvey’s other Writings and Medical Practice. — The remaining writings of Harvey which are extant are unimportant. A complete list of them will be found below, together with the titles of those which we know to be lost. Of these the most important were probably that on respiration, and the records of post-mortem examinations. From the following passage (De partu, p. 550) it seems that he had a notion of respiration being connected rather with the production of animal heat than, as then generally supposed, with the cooling of the blood. “Haec qui diligenter perpenderit, naturamque aeris diligenter introspexerit, facile opinor fatebitur eundem nec refrigerationis gratia nec in pabulum animalibus concedi. Haec autem obiter duntaxat de respiratione diximus, proprio loco de eadem forsitan copiosius disceptaturi.”

Of Harvey as a practising physician we know very little. Aubrey tells us that “he paid his visits on horseback with a foot-cloth, his man following on foot, as the fashion then was.” He adds—“Though all of his profession would allow him to be an excellent anatomist, I never heard any that admired his therapeutic way. I knew several practitioners that would not have given threepence for one of his bills” (the apothecaries used to collect physicians’ prescriptions and sell or publish them to their own profit), “and that a man could hardly tell by his bill what he did aim at.” However this may have been,—and rational therapeutics was impossible when the foundation stone of physiology had only just been laid,—we know that Harvey was an active practitioner, performing such important surgical operations as the removal of a breast, and he turned his obstetric experience to account in his book on generation. Some good practical precepts as to the conduct of labour are quoted by Percivall Willughby (1596–1685). He also took notes of the anatomy of disease; these unfortunately perished with his other manuscripts. Otherwise we might regard him as a forerunner of G. B. Morgagni; for Harvey saw that pathology is but a branch of physiology, and like it must depend first on accurate anatomy. He speaks strongly to this purpose in his first epistle to Riolan: “Sicut enim sanorum et boni habitus corporum dissectio plurimum ad philosophiam et rectam physiologiam facit, ita corporum morbosorum et cachecticorum inspectio potissimum ad pathologiam philosophicam.” The only specimen we have of his observations in morbid anatomy is his account of the post-mortem examination made by order of the king on the body of the famous Thomas Parr, who died in 1635, at the reputed age of 152. Harvey insists on the value of physiological truths for their own sake, independently of their immediate utility; but he himself gives us an interesting example of the practical application of his theory of the circulation in the cure of a large tumour by tying the arteries which supplied it with blood (De generat. Exerc. xix.).
Encyclopædia Britannica, Eleventh Edition, Cambridge: University Press, 1910. Vol. XIII, pp. 42-46.