Page:The Harveian oration, 1875 (IA b22314611).pdf/24

 left ventricle and aorta; also that the contraction of the left ventricle and the pulse in the arteries are cause and effect. If the one ceases the other stops; as the one is strong or weak, so is the other.The pulse is small and weak in aneurism, of which Harvey gives a case, for then the blood is diverted into the tumour, and so intercepted. Again, when an artery is punctured or divided, the blood is seen to spout forth with violence the instant the ventricle contracts. This is true of all arteries: of the pulmonary artery; of the vessel which leads from the heart of a fish to its gills.

Here again Harvey finds an error to correct. It was the commonly received opinion that the arteries are filled by expanding like bellows. He illustrates the true state of the case by the analogy of blowing into a glove. At the same time he takes occasion to give Aristotle his due, who says that, “the blood of all animals palpitates within their veins (meaning the arteries), and by the pulse is sent everywhere simultaneously that these vessels “all depend upon the heart,” and move with it.

Passing now from the motions of the heart to the large vessels that enter and leave it, Harvey takes in hand the circulation through the lungs;