68z THE POPULAR SCIENCE MONTHLY. 



sistently maintained, the blood more than ever believed to be the 

 principle of life, and, with the knowledge of its circulation in the or- 

 ganism, 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 Martiniere, 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 " prac- 

 tice," he says, "cannot be allowed, short of altering all ancient medi- 

 cine." 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 9 

 . 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 asrainst 

 the operation, but will oppose them by experience alone. The first 

 two transfusions successfully practised on man are recorded in " a let- 

 ter written to M. de Montmor, privy councillor to the king, and chief 

 master of requests, by J. Denis, doctor of medicine, professor of philoso- 

 phy 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 friend- 

 ship, and when that learned philosopher died, after many personal 

 labors in the most varied branches of knowledge, De Montmor pub- 

 lished 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 



