108 MICROBES AND TOXINS 



disease which resembles hydrophobia, the acute poHomyelitis 

 of children, has recently been studied by the same experimental 

 method. 



The microbial doctrine has still opponents, more or less 

 masked, who accuse microbiologists of being able to see 

 nothing but the microbe and of imagining that this is the 

 whole malady. The body takes some part, there is no doubt ; 

 the malady is a sort of fermentation, but one taking place in a 

 medium capable of resisting the ferment. Pasteur recreated 

 medicine by introducing into it the spirit and method of the 

 exact sciences, but he knew as well as any that diseases do not 

 rage in an inert material. This, however, does not prevent the 

 various incidents of the disease from being at bottom physico- 

 chemical phenomena. 



The Origin of Pathogenic Microbes. — The pathogenic 

 microbes are not instruments of a perfidious Providence, and 

 created to chastise man, animals, and plants. The pathogenic 

 species, are species the result of selection and adaptation. They 

 grew first of all as saprophytes on individuals who suffered no 

 damage, as is the case to-day with many bacteria growing on 

 animal bodies. They multiplied upon ill-nourished and 

 fatigued individuals and found on a definite animal species 

 nutritive materials and a chemical " soil " which suited them. 

 Certain bacteria have become strict parasites, incapable of 

 living even temporarily in the external world, e.g., the bacillus of 

 leprosy. These views of Pasteur are quite in conformity with 

 the spirit of Darwinism. 



From the beginning there has been happening what occurs 

 every day, i.e., there has been a struggle between the parasite 

 and the body. Not only does the body defend itself against 

 the bacteria, but the bacteria defend themselves against the 

 body. Each is capable of gathering strength or immunising 

 itself against the other, and these are simply different aspects 

 of adaptation and of natural selection. " The science of 

 bacteria, as with all the branches of biology, has profited by 

 the theory of evolution and, making a just return, it has 

 supplied the Darwinian theory with a striking confirmation. 



