138 SUPER-ORGANIC EVOLUTION 



that have been observed, series which lead from 

 the simple touch of fever to the most characteristic 

 typhoid." 1 



What is the origin of infectious diseases ? Do 

 they reveal their origin in the external medium 

 or in the human organism itself? Facts, in the 

 majority of cases and in diseases peculiar to man, 

 appear to leave no room for doubt that in many 

 cases the origin of the diseases that afflict man 

 resides in man himself. 



Microbes dwell inoffensively in the sound man, 

 because the normal state of the secretions so 

 requires it ; but if wrong conditions of existence 

 succeed in altering the chemical action, or the 

 normal formula, the change which of necessity this 

 causes the medium man to undergo, alters the 

 normal state of these microbes and renders them 

 virulent. This is what would result, according to 

 Rodet and Roux, with the Bacterium coli-comune 

 on producing typhoid ; and this is what occurs 

 in pneumonia and diphtheria. 



The microbes that produce pneumonia and 

 diphtheria may live normally in the mouth of a 

 man, being completely harmless. But it may 

 happen that some changes in the medium or in the 

 subject so alter his chemical composition as to 

 modify also the secretions of the glands of the 



1 Bouchard, Pathologic generale, p. 480. 



