Page:The Harveian oration, 1875 (IA b22314611).pdf/20

were, in a labyrinth from which he can only extricate himself by using greater and daily diligence, by performing frequent vivisections of a variety of animals, and by the collation of numerous observations. Having by these means discovered “ both the motion and use of the heart and arteries,” he proceeds to enlighten not only his friends, but the public also in his anatomical lectures, after the manner of the academy of old.

But Harvey, though he does not tell us when he first began to suspect the true state of things, lets us into the secret of the process of thought by which he attained to his grand inference. He surveys his mass of evidence drawn from vivisections, and his reflections on them, on the structure of the heart and of its ventricles, on the symmetry and size of the conduits which enter into and issue from them, on the arrangement and intimate structure of the valves, with many things besides; and then frequently and seriously revolving in his mind what might be the quantity of blood transmitted, in what time, and the like, and deeming it impossible that this quantity could be supplied by the juices of the ingested aliment, without draining the veins on the one hand, or