LIFE OF ELIE METCHNIKOFF 121 



method for the comprehension of truth and lead to a definite 

 conception of life, or at least allow ua to approach one. 



And yet, until then, the theory of phagocytosis 

 as a curative force of the organism was but a hypo- 

 thesis, for he had not yet observed spontaneous 

 phagocytosis in diseases and did not know pathogenic 

 microbes. He therefore sought to study them in lower 

 animals, whose simple structure made the observa- 

 tion easier. He found some small, transparent, fresh- 

 water crustaceans, called daphnice, which were diseased 

 and easy to place alive under a microscope. These 

 crustaceans are often infected by a parasite fungus 

 (Monospora bicuspidata), of which the spores, shaped 

 like sharp needles, are introduced with food into the 

 digestive tube, traverse the walls of it, and thus 

 penetrate into the general cavity of the body. They 

 are immediately attacked by mobile phagocytes, 

 which either singly or in groups englobe them ; if the 

 phagocytes succeed in digesting the spores, the 

 daphnia recovers ; in the contrary case, the spores 

 germinate and develop into small fungi which invade 

 the organism and kill it. The recovery or death of 

 the daphnia depends therefore on the issue of the 

 struggle. 1 This observation gave final confirmation 

 to the hypothesis of the curative forces of the organism. 



Metchnikoff was not content with observing lower 

 animals but wished to study the reaction of the 

 organism of mammals in infectious diseases. At that 

 time, the best-known microbe was the bacillus of 

 anthrax. He therefore chose that for his researches 

 and ascertained that phagocytosis varied with the 

 virulence of the microbes ; thus, while phagocytes did 



1 Virchow's Archiv, vol. 96, p. 177. 



