218 LIFE OF ELIE METCHNIKOFF 



could not leave Sarepta, for all the members of both 

 branches of the mission had agreed to meet there in 

 order to sum up the results of their observations. 



The researches of the expedition for the study of 

 plague were not finished, and the Russian mission 

 had agreed to complete them. So far, it was estab- 

 lished that neither the corpses — after a certain time 

 — nor the ground, nor the surrounding animals con- 

 tained any plague microbes, and no carriers had been 

 .found among the Kirghiz population. 



The data gathered among the Kalmuk population 

 justified Metchnikoff's hypothesis. In the centre of 

 the steppes, where the Kalmuks were still isolated, 

 tuberculosis was completely unknown ; diagnosis 

 reactions were negative. They became positive more 

 and more frequently as we came nearer the periphery 

 of the steppes and the Russian population. The 

 extreme sensitiveness of the Kalmuks must there- 

 fore depend on the fact that they have suffered no 

 natural vaccination in the steppes, which would 

 support the idea that some natural vaccine exists 

 amongst us. Metchnikoff therefore concluded that 

 he might direct ulterior researches towards the quest 

 of natural tuberculous vaccines. Such were the 

 scientific results of the expedition. 



Apart from that, the journey to Russia had a 

 strong personal influence on Metchnikoff. He had 

 formerly left his country under the impression of the 

 fatal error committed by the revolutionaries in 

 killing Alexander II., an error which had led to a 

 protracted reaction. He had therefore remained very 

 sceptical concerning the Russian revolutionary move- 

 ment ; he thought that the necessary reforms might 

 come from a Government evolution. But, during his 



