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Anatomia Animata: Anatomy and Medicine in William Harvey's Century

Circulation of the Blood

According to Galenic physiology, there are two types of blood: venous blood, which is made in the liver and travels to the extremities where it is consumed, and arterial blood, which is made in the heart and also travels throughout the body. On this account, both types of blood ebb and flow throughout the body and do not "circulate" in the manner we understand today. In the early seventeenth century, William Harvey proved that blood flows directionally away from the heart through the arteries and back to the heart through the veins. Several individuals had known of circulation earlier – namely Ibn al–Nafis (1213–1288), Michael Servetus (1511–1553), and Realdo Colombo (1516–1559) – but the question was largely laid to rest by Harvey's experiments presented in De Motu Cordis. Works by Harvey, Hieronymous Fabricius (Harvey's teacher), and Richard Lower (one of Harvey's most famous followers) are displayed on this page.

Richard Lower. Tractatus de Corde. Item de Motu & Colore Sanguinis et Chyli in Eum Transitu. London: Typis J. Redmayne, Impensis Jacobi Allestry, 1669.

Lower's treatise is as rare as it is significant in the history of medicine. Tractatus de Corde presents Lower's research on blood transfusion, the muscular anatomy and nerve supply of the heart, and the means by which the heart pumps blood throughout the body. Lower did not believe — as many of his forebears and contemporaries did — that the blood contained a nitrosulfureous ferment and instead thought the blood "too inert to effervesce so violently and suddenly in the Heart or its vessels" (62). Lower also poignantly asked, "if the blood moves on its own power, why does the Heart need to be so fibrous and so well supplied with Nerves?" (64). Furthermore, this work is of great importance as it includes Lower's argument that the color of the blood is related to the presence or absence of air rather than any form of cardiac effervescence. This was demonstrated in two ways: by showing that blood from the pulmonary artery looks the same as venous blood, and by blocking the trachea of a live animal, demonstrating that the blood that passes through the air–blocked lungs does not change color, while in healthy lungs it does.

Hieronymus Fabricius ab Aquapendente. De Venarum Ostiolis. Padua: Ex Typographia Laurentii Pasquati, 1603.

In De Venarum Ostiolis, Hieronymus Fabricius recounted his discovery of the valves in the veins, which would prove to be one of the most important discoveries in the seventeenth century. Fabricius mistakenly believed that their function was to delay the movement of blood as it ebbed and flowed throughout the veins. Nevertheless, this work profoundly influenced his pupil, William Harvey, who demonstrated the circulation of the blood and published his results in 1628 in his famous De Motu Cordis (also displayed on this page).

As can be seen in the other books in this section, Fabricius' spectacular images were reproduced by Harvey and Richard Lower, a follower of Harvey's. Among other early–seventeenth–century anatomical works, the images produced by Fabricius were matched in quality by very few.

In addition to its significance in the history of anatomy, De Venarum Ostiolis is a very rare book, with many copies surviving only through their shared binding with Fabricius' other works.

William Harvey. Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus ... Frankfurt: Sumptibus Guilielmi Fitzeri, 1628.

Harvey's most famous work, known as De Motu Cordis, is considered by many to be the most important book in the history of medicine. Harvey demonstrated in 1616 that the blood in animals and humans is impelled in a circle by the pulsation of the heart, passing away from the heart through arteries and returning to the heart through the veins. However, he did not publish his results until 1628.

Harvey cleverly demonstrated the circulation of the blood in several ingenious experiments. According to Galenic physiology, nutritive blood produced in the liver and arterial blood produced in the heart ebbed and flowed throughout the body and were consumed when they reached various body parts. To rebut this, Harvey estimated on the capacity of a human heart, how much blood the heart expels in a single beat, and how many beats it produces in a given period. He thus estimated that 10 lbs. and 6 oz. of blood flow through the heart in one half hour. This means that on the Galenic model, 540 lbs. of blood must be produced and consumed in a single day.

In a different experiment, Harvey replicated what Fabricius had done and tied a ligature around the upper part of a man's arm. He observed that when tied tightly, the flow of blood into the lower portion of the arm was cut off (because arteries are deeper set in the tissue than veins). When loosened slightly, blood flowed into the lower part of the arm but was unable to escape back to the upper part. Harvey recognized this when the veins became more visible as they were engorged with blood. Furthermore, as the veins swelled, Harvey noticed small bumps in the veins, which were the valves discovered by Fabricius. If one took a finger and sought to force the blood away from the shoulder and toward the hand, it would quickly become clear that blood is unable to flow in that direction. The valves in veins prevent the backward flow of blood.

Most of Harvey's other experiments were based on the animal vivisection. In one experiment he vivisected a snake and ligated the vena cava, demonstrating how the heart fails to fill with blood; he then ligated the aorta, showing that the blood cannot escape, and therefore the heart becomes engorged with blood.

Hieronymus Fabricius ab Aquapendente. Opera Physica Anatomica ... Padua: Sumptibus Roberti Meglietti, 1625.

These images are taken from an edition of De Venarum Ostiolis within Fabricius' complete works. The book owned by The Lilly Library belonged to Fabricius' student, William Harvey, and contains his marginal annotations on multiple pages. This is one of only a half–dozen books owned by Harvey that have survived, all of which barely escaped the great fire of London in 1666. All other books owned by Harvey are located in London.

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