xix.] PATHOGENIC ORGANISMS. 251 



plugging up the capillaries of vital organs, a theory upheld 

 by some observers from the fact that in most cases the 

 capillaries appear filled with the bacilli, and in some cases 

 in extensive regions, lung, kidney, and spleen, the capillaries 

 are almost occluded by the bacilli. We must assume, then, 

 that although as a rule immediately before death all the con- 

 ditions are present to enable the bacilli to multiply readily 

 and to produce a large crop, this is not necessarily connected 

 with the cause of death, being in fact in consequence of the 

 animal being in articulo mortis ; but that the immediate 

 cause of death is the chemical alteration produced by the 

 bacilli in the blood and tissues. For producing this effect it 

 is not necessary to have more than a certain number of the 

 bacilli. As soon as this number is reached death follows. 

 The same may be said of other pathogenic organisms. 

 Thus for instance in the case of tubercle-bacilli, after the in- 

 troduction of these into the subcutaneous tissue of a guinea- 

 pig, multiplication takes place, and after they reach a certain 

 number, the nearest lymph-glands become swollen and 

 inflamed and then caseous : but this stands in no relation to 

 the number of the bacilli, for in some instances the micro- 

 scopic examination reveals only very few bacilli, they are 

 scattered in very small numbers over very wide areas. And 

 the same is observed in the tuberculous deposits of the 

 internal organs. In some of them the bacilli are exceedingly 

 scarce, while in others neither more nor less advanced they 

 are numerous. Here also we must assume that as soon as 

 a certain, perhaps even small, number of the bacilli have 

 been produced, the chemical effect produced is sufficient to 

 be the cause of a certain pathological change. In glanders 

 the nodules in the skin and lung reveal sometimes, even 

 under the most careful examination after approved methods, 

 the presence of but very few bacilli. In swine-plague, in 



