Page:The Harveian oration, 1875 (IA b22314611).pdf/25

 and finds himself freed from the doubts and difficulties which perplexed other men, by enlisting on his side that comparative anatomy, and those vivisections which they had neglected. For he tells them that they do amiss when they (as most anatomists do) limit their researches to the human body, and that when it is dead.

First then, he tells us that in fishes, which have no lungs to embarrass the inquiry, hut a sac like an auricle, a single ventricle, and a vessel analogous to an artery, the blood may be seen to be driven into the vessel at each beat of the heart, and, if the vessel be divided, to issue in jets. Again, in toads, frogs, serpents, and lizards, which have lungs in a certain sense, and a voice, the blood is transferred, as in the higher animals, from veins to arteries by the action of the heart, their case being, to all intents and purposes, that of a man in whom the septum of the heart should be perforated or removed, or one ventricle made out of two—a state of things which does really exist in the embryos of those animals that have lungs, as Harvey proceeds to prove in the course of a luminous description of the foetal heart and large vessels, both in man and in animals.