In his physiology, I can refer to but one point--the pivotal question of the heart and blood vessels.

To Aristotle the heart was the central organ controlling the circulation, the seat of vitality, the source of the blood, the place in which it received its final elaboration and impregnation with animal heat.

The blood was contained in the heart and vessels as in a vase--hence the use of the term "vessel." "From the heart the blood-vessels extend throughout the body as in the anatomical diagrams which are represented on the walls, for the parts lie round these because they are formed out of them."(29) The nutriment oozes through the blood vessels and the passages in each of the parts "like water in unbaked pottery." He did not recognize any distinction between arteries and veins, calling both plebes (Littre); the vena cave is the great vessel, and the aorta the smaller; but both contain blood.

He did not use the word "arteria" (arthria) for either of them.

There was no movement from the heart to the vessels but the blood was incessantly drawn upon by the substance of the body and as unceasingly renewed by absorption of the products of digestion, the mesenteric vessels taking up nutriment very much as the plants take theirs by the roots from the soil.