sistently maintained, the blood more than ever believed to be the principle of life, and, with the knowledge of its circulation in the organism, comes the suggestion "to transfer blood from a young to an old person, from a healthy to a sick one, from cold to warm, from bold to timid people, from tamed to wild animals." But Galen's words are fully accepted; the theory of "animal spirits" rules unquestioned, and Descartes has given the system new vigor. That philosopher holds that there are in us two things—the spiritual life, comprising the soul, and the material life, formed by spirits, which he ingeniously compares to the restless particles of a wavering flame An unknown disciple of the great master, De Gurue, maintains the ideas of the new school in speaking of the transfusion of blood. "The blood of animals," he says, "containing a great quantity of spirits, cannot be mingled with that in the body of another animal of the same kind without fermentation, and cannot ferment without causing fever." For some persons, as Martin de la Martiniére, the transfusion of blood is a barbarism, and those who practise it are "butchers and cannibals." Others think of it, with Eutyphronis, that it errs by oversetting traditions. This "practice," he says, "cannot be allowed, short of altering all ancient medicine." The partisans of bleeding, disciples of Guy Patin, thought that transfusion of blood would overwhelm the patient, and increase what should be taken away from him. The eclectics, in fine, believe that this operation brings its supporters and its opponents into agreement: the first, because it carries off corrupt blood; and the last, because, by the supply of new blood in place of that removed, the strength of the patient is not lessened.
All these theoretical discussions might have continued forever, had not Dr. Denis cut them short in 1667. He looks for the solution of most questions in physics by experience, not by argument. Zeno affirms that every thing in the world is immovable. Diogenes walks for his only answer. Denis allows no other rule of action; he will not lose time in refuting the reasons of those who have written against the operation, but will oppose them by experience alone. The first two transfusions successfully practised on man are recorded in "a letter written to M. de Montmor, privy councillor to the king, and chief master of requests, by J. Denis, doctor of medicine, professor of philosophy and the mathematics." It is worth while to introduce, in few words, the eminent man to whom this work was addressed. M. de Montmor, a member and one of the founders of the French Academy, lived in the centre of scientific movement. Gassendi honored him with his friendship, and when that learned philosopher died, after many personal labors in the most varied branches of knowledge, De Montmor published a complete edition of his works. In the years preceding and following the foundation of the Academy of Sciences, before and after 1666, his house was a centre at which physicists and savants gathered every week to discuss the interesting questions of the day, and the