From the lungs was absorbed the pneuma, or spiritus, which was conveyed to the heart by the pulmonary vessels--one to the right, and one to the left side.

These vessels in the lungs, "through mutual contact" with the branches of the trachea, took in the pneuma.

A point of interest is that the windpipe, or trachea, is called "arteria," both by Aristotle and by Hippocrates ("Anatomy," Littre, VIII, 539).

It was the air-tube, disseminating the breath through the lungs.

We shall see in a few minutes how the term came to be applied to the arteries, as we know them.