xix.] PATHOGENIC ORGANISMS. 249 



would be capable of thriving and of producing the 

 disease. 



The next point to consider is the relation of the specific 

 micro-organism to the essence of the disease, or in other 

 words the question whether the organism itself is the virus or 

 whether this latter is the product of the former, something 

 in the same way as the septic ferment if. the product of the 

 putrefactive organisms ? 



That the virus in the infectious diseases is intimately con- 

 nected with the organisms is proved by the fact that the 

 virus introduced into the body multiplies ad infinitum ; for 

 instance, in anthrax or tuberculosis after the introduction of 

 an infinitesimal dose, we find the disease (malignant anthrax 

 or general tuberculosis respectively) sets in in its virulent 

 form ; in the first case every drop of blood teems with the 

 bacillus anthracis ; in the second (tuberculosis) every tuber- 

 culous caseous particle in the lymph-glands, lungs, spleen 

 and liver contains the bacilli ; in both instances crops of the 

 bacilli are produced in the afflicted body, and every particle 

 of the tissue containing the bacilli is capable of starting the 

 disease when introduced into a fresh subject. Moreover the 

 artificial cultures of the pure bacilli are possessed of the 

 same pathogenic power. The same holds good for leprosy, 

 for erisypelas, for swine-plague, &c. So that the proposition 

 that the organisms are intimately connected with the virus 

 must be considered as well established. 



But even after this it remains an open question whether 

 the organism is identical with the virus, or whether the 

 organism is concerned in elaborating the virus a sort of 

 ferment ; and further, whether the virus being the latter's 

 product, is obtainable apart from the organism. 



Let us start with the proposition that the virus is a product 



