CHAPTER XIX. 



VITAL PHENOMENA OF PATHOGENIC ORGANISMS. 



As has been stated in the preceding chapter, the specific 

 micro-organisms have the great differential character that 

 they are capable of existing and propagating themselves in 

 healthy living tissues. In those species in which the com- 

 plete series of proofs has been furnished to establish the fact 

 that the micro-organisms are intimately associated with the 

 cause of the malady (e.g. malignant anthrax, tuberculosis, 

 swine-plague, erysipelas), in which it has been shown beyond 

 doubt : (a) that an animal suffering from the malady contains 

 in definite distribution the particular micro-organism, (b) 

 that the micro-organisms, cleared by successive artificial 

 cultures from any adhering hypothetical chemical virus, when 

 introduced into a suitable animal produce the malady, (c) 

 that every such affected animal contains the micro-organism, 

 in the same distribution and relation to the diseased organs 

 as the original animal dead after disease in those, instances, 

 I say, the only way of understanding the effect of the micro- 

 organisms is to assume, what is actually the case, that the 

 micro-organisms introduced into the living tissue go on 

 multiplying, and directly or indirectly, i.e. themselves or 

 by their products, as will be stated below, produce certain 



