LIFE OF ELIE METCHNIKOFF 151 



object in view, Metchnikoff undertook new researches 

 and succeeded in ascertaining once for all the narrow 

 link between immunity and the function of the 

 phagocytes which probably elaborate the antitoxins 

 as a product of their digestion of vaccinal toxins. He 

 drew this conclusion from the fact that, in a rabbit 

 vaccinated against hog-cholera, the exudate devoid 

 of phagocytes 1 is neither bactericidal, nor antitoxic, 

 nor attenuating, while it is so if it contains phagocytes. 

 Therefore a relation of causality exists between cells 

 and the acquired properties of humors. And the 

 resistance of the animal is in visible correlation with 

 the degree of phagocytosis which is manifested by it. 



These results having been established, it seemed 

 as if the last rampart of the humoral theory had been 

 taken by storm. 



In the meanwhile the persistent and bitter opposi- 

 tion of physicians to the phagocyte theory made a 

 great impression on Metchnikoff, and, while stimu- 

 lating his energy in defence of his ideas, it maintained 

 him in a state of nervous excitement and even 

 depressed him. 



He asked himself why this obstinate opposition 

 to a doctrine based on well-established facts, easily 

 tested and observed throughout the whole animal 

 kingdom ? To him, a naturalist, it seemed clear and 

 simple and all the more admissible that it was con- 

 firmed by the generality of its application to all 

 living beings. 



But, he thought, perhaps the real cause of the 

 attitude of the contradictors lies in the very fact 

 that medical science only concerns itself with the 

 pathological phenomena of higher animals, leaving 



1 Aqueous humor, the exudate of aseptic oedemata. 



