Exclusively an anatomist, he makes but brief references in his great work to the functions of the organs which he describes. Where he differs from Galen on these matters he does so apologetically. He follows him in regarding the heart as the seat of the emotions and passions—the hottest of all the viscera and source of heat of the whole body; although he does not, as Aristotle did, look upon the heart as giving rise to the nerves. He considers the heart to be in ceaseless motion, alternately dilating and contracting, but the diastole is in his opinion the influential act of the organ. He knows that eminences or projections are present in the veins, and indeed speaks of them as being analogous to the valves of the heart, but he denies to them the office of valves. To him the motion of the blood was of a to-and-fro kind, and valves in the veins acting as such would have interfered with anything of the sort. He expresses clearly the idea, that was entertained in the old physiology, of the attractions exerted by the various parts of the body for the blood; and especially that of the veins and heart for the blood itself. "The right sinus of the heart," he says, "attracts blood from the vena cava, and the left attracts air from the lungs through the arteria venalis (pulmonary vein), the blood itself being attracted by the veins in general, the vital spirit by the arteries." Again, he speaks of the blood filtering through the septum between the ventricles as if through a sieve, although he knows perfectly well from his dissection that the septum is quite impervious.
It will thus be seen that the physiological teaching of Galen was left undisturbed by Vesalius.
FOOTNOTES:
[19] See Professor Morley's article on "Anatomy in Long Clothes," in Fraser's Magazine, 1853, from which most of the facts in this sketch have been taken.