Page:The growth of medicine from the earliest times to about 1800.djvu/413



THE CONTRIBUTIONS MADE BY DIFFERENT MEN DURING THE RENAISSANCE, AND MORE PARTICULARLY BY WILLIAM HARVEY OF ENGLAND, TO OUR KNOWLEDGE OF THE CIRCULATION OF THE BLOOD, LYMPH AND CHYLE

Among the earliest known doctrines relating to the nature of the blood and its mode of distribution throughout the body are those attributed to Erasistratus and Galen; for the still more ancient ones, of which Diogenes of Apollonia, Aristotle and the Hippocratic writers are reputed to be the authors, are too incomplete to call for serious consideration in this place.

(a) The Doctrine Taught by Erasistratus.—Erasistratus, who was born at Julis in the Island of Ceos (Aegean Sea) during the third century before Christ, held the belief that the arteries contain only air, which is drawn into the lungs by way of the trachea and bronchi, whence it enters the pulmonary vein (called by him the "venous artery"). In its further course this air passes from the pulmonary vein into the left ventricle of the heart, and is then conveyed from that organ through the arteries to the different tissues of the body. Erasistratus further taught that the smallest subdivisions of both the arteries and the veins lie side by side in the tissues, and that, in certain abnormal bodily conditions, they communicate the one with the other through anastomoses; but that, in a normal condition of the body, no communication takes place between the two. In common with all other physicians of that time, he believed that only the veins carry blood. Here, then, we