Those who to-day are so familiar with the course of the circulation of the blood through the arteries and veins find it difficult to understand how the recognition of this phenomenon could have been so long delayed; it seems so simple, yet to the ancients it was perfectly incompre-hensible! Although every one had recognized that blood would flow from an incision, few stopped to reason thereupon. From time immemorial it had been supposed that the veins had their origin in the liver, and were the only vessels which contained blood, since the arteries were always found empty after death; the latter were held to contain only air or spirit. The circulation was supposed to leave and return to the liver through the venous canals by undulating movements similar to those of the waves of the ocean; and this was the doctrine of the Asclepiadæ, and probably of Erasistratus. Galen modified this view by showing that the arteries contained blood; he knew it was poured into the right cavities of the heart by the great veins, but he believed that only a small quantity passed from the right ventricle into the lungs, and that the major portion reached the left ventricle by passing through pores in the inner ventricular septum. This opinion was uncontested until the middle of the sixteenth century.
Then the theologian, Michael Servetus, who, in 1553, perished as the victim of Calvin's jealousy, denied the passage of the blood through this septum, contending that it was returned from the lungs to the left side of the heart by the pulmonary veins. This was a happy thought, and a great step toward the truth. Soon after Columbus demonstrated anatomically that the conjecture of Servetus was plausible, by showing the function and real use of the valves of the heart. Cesalpinus came still nearer to the truth, and explained, as did Columbus, the course of the circulation through the lungs, but he opined that blood and vital spirits passed from the arteries into the veins during sleep, because at that time there was swelling of the latter and diminution of the pulse. Valves in the veins were known, and it had been shown that ligature of an artery in the living animal stopped the flow below it, while if a vein were tied there was shrinkage above the ligature, and swelling below it. Such was the state of science at the beginning of the seventeenth century; there remained, practically, but one step to take,—to find the true course of the blood.
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William Harvey was born in Folkestone, Kent, in 1578 and died in London in 1637. He first studied at Cambridge, entering at the age of fifteen; subsequently traveled in France, Germany, and Italy, remaining in Padua from 1599 to 1602, in order to hear the lectures of Fabricius ab Aquapendente. With the title of "Doctor" he returned and settled in London and soon became a member of the College of Medicine, of which he was made a regent in 1613; in time he became physician to James I, and, on the demise of this sovereign, to Charlçs I; to the latter he dedicated his chief work. During the civil war he was driven from place to place, and, finally, to Oxford, where he surrendered himself to the Parliamentary troops, after which he again resided in London with his brothers, who had become rich. Modesty led him to decline the high distinction of President of the College of Physicians, and he lived a quiet and retired life, occupied with his studies and, in his later years, investigations in mathematics. Soon after 1613 he began, through his lectures, to make known the doctrine of the circulation of the blood; but he did not publish the results of his researches until 1628, after submitting them to fifteen years of proofs and counterproofs of every kind. So bitter was the opposition of his contemporaries to the new doctrine that he at one time lost a part of his practice, and was even held to be demented. It is characteristic of the fate of new truths, as well as of that age of dominant authority, that his first publication—Concerning the Motions of the Heart and the Blood—was unable to pass censorship in England, and therefore appeared in a foreign country (Frankfort, in 1628) when he was fifty years old; but his second treatise on the same subject, in reply to Riolan, a professor in the Faculty of Paris, was published in Cambridge in 1649.
"So much care and circumspection in search for truth, so much modesty and firmness in its demonstration, so much clearness and method in the development of his ideas," says Renouard, "should have prepossessed every one in favor of the theory of Harvey; but, on the contrary, it caused a general stupefaction in the medical world, and gave rise to great opposition."
This theory, which to-day appears so natural that we conceive with difficulty why it was not sooner discovered, was nothing less than a revolution in physiology; it excited a tremendous controversy that continued more than twenty-five years, and in which mingled every one possessed of any pretension to knowledge of anatomy or physiology; even naturalists and philosophers took part in the dispute. René Descartes was the first to declare in its favor and to support it by experiment; John Walæus (Jan de Wale), the celebrated Professor of Anatomy in the University of Leyden, confirmed it by new observations; finally Plempius, of Louvain, for a time one of the most fiery of opponents, succumbed to the truth, and in 1652 passed publicly to the ranks of Harvey's followers—no small triumph!
During these long debates Harvey remained always dignified and firm, although the early attacks rendered him unduly sensitive regarding others which he anticipated.
About his only answer to the arguments adduced against him, was to add new proofs and new experiments to those already published. The only one of his adversaries who obtained a direct response was Riolan, who possessed immense influence among his contemporaries as a man of attainments; Riolan combated with equal violence and obstinacy the other great discovery of the age,—viz., the circulation of the lymph. Harvey ultimately, however, had the satisfaction of seeing his theory universally adopted. But his services were not limited to this one discovery. He made most interesting observations on generation, both in man and in animals; on midwifery; and on the structure and diseases of the uterus.