280 LIFE OF ELIE METCHNIKOFF 



blood, etc., were but the natural development of 

 those premises. 



He had proved that the part played by the phago- 

 cytes consists, not only in the struggle against microbes 

 and their poisons, but also in the destruction of all 

 the mortified or enfeebled cells of the organism, and 

 that atrophies are nothing more than the absorption 

 of cellular elements by the phagocytes. 



He found that senile atrophies have the same 

 cause, and asked why the cells of old people's 

 organisms should become enfeebled. 



He demonstrated that the principal cause is the 

 chronic poisoning of the cells by toxins manufactured 

 by microbes in the intestine. Premature senility was 

 the result a phenomenon as pathological as any 

 disease. 



The source of the evil, therefore, resides in the 

 intestinal flora. Accordingly he started to study the 

 latter, as also senility, in order to find means of 

 struggling against both. 



His researches enabled him to indicate a series of 

 means, based, on the one hand, on the struggle against 

 microbes, and, on the other, on the defence of the 

 noble cells against destructive ones. 1 



The study of old age led him to that of syphilis, 

 a disease which provokes an arterio-sclerosis which is 

 similar to that of old people ; the study of the normal 

 intestinal flora was followed by that of intestinal 

 diseases, such as typhoid fever and infantile cholera. 



Finally, he progressed towards the last pheno- 

 menon, the most mysterious in nature, Death. 



1 Replacement of the wild and noxious flora of the intestines by 

 antagonistic cultivated microbes ; strengthening and vaccinating of noble 

 cells. 



