156 LIFE OF ELIE METCHNIKOFF 



simultaneous ingestion of the cholera vibrio and of 

 favourable microbes did not induce cholera. 



The flora of the intestines, complex as it is, probably 

 played a part on which it was difficult to throw any 

 light. Yet Metchnikoff did not give up the idea of 

 producing a vaccine against this disease with attenu- 

 ated microbes, or, if not, to prevent its inception by 

 preventive microbes. His thesis was strengthened 

 when one of his pupils, Dr. Sanarelli, discovered a 

 series of choleriform bacilli in the absence of any 

 cholera epidemic, one of those microbes being found 

 at Versailles, a town which had remained immune 

 during every cholera epidemic. 



Metchnikofi thought that this microbe, or some 

 choleriform bacillus, similar though not specific, prob- 

 ably served as a natural vaccine against cholera in those 

 localities which were spared by the epidemic though 

 the cholera vibrio was brought there. This was a 

 question that could only be solved by experiment. 



At the time when he had himself absorbed a 

 cholera culture, Metchnikofi admitted the risk of 

 catching the disease ; still, his eagerness to solve the 

 problem had silenced in him all other considerations 

 and feelings opposed to his irresistible desire to attempt 

 the experiment. This " psychosis," as he himself 

 called it later, recurred now, in spite of all the emotions 

 he had gone through on the previous occasion, and he 

 decided once again to experiment on man. It is true 

 that he now only had to deal with choleriform microbes 

 from Versailles which he believed to be quite harm- 

 less as they came from the water of a locality free 

 from cholera. He therefore ingested some of the 

 Versailles choleriform vibriones and gave some to 

 several other people. Contrary to expectation, one 



