He studied particularly the movements of the heart, the action of the valves, and the pulsatile forces in the arteries.

Of the two kinds of blood, the one, contained in the venous system, was dark and thick and rich in grosser elements, and served for the general nutrition of the body.

This system took its origin, as is clearly shown in the figure, in the liver, the central organ of nutrition and of sanguification.

From the portal system were absorbed, through the stomach and intestines, the products of digestion.

From the liver extend the venae cavae, one to supply the head and arms, the other the lower extremities: extending from the right heart was a branch, corresponding to the pulmonary artery, the arterial vein which distributed blood to the lungs.