120 INFECTION AND IMMUNITY. 



lished it is of long duration. Such strains are 

 called "chemoresistant." It has also been shown 

 that trypanosomes acquire a resistance to the 

 germicidal properties of serum, as in the case of 

 bacteria. 

 capsule i n view of the fact that some micro-organisms 



Formation. 



produce a capsule when grown in the animal body, 

 whereas it is absent in ordinary culture media, it 

 has been supposed by some that the capsule is an 

 expression of adaptation on the part of the organ- 

 ism to the germicidal agencies of the host, that it 

 is perhaps protective in its character. Such 

 observations have been made in relation to the 

 anthrax bacillus (Deutsch and others), the strep- 

 tococcus (Bordet, Marchand and others), and the 

 plague bacillus (Lohlein). 2 This relationship, how- 

 ever, is not general, and can hardly be considered 

 as thoroughly established. 



^ n ao ^dition to this more or less passive adapta- 

 tion on the part of micro-organisms, there is rea- 

 son to believe that they may actually antagonize 

 the protective agencies of the body, particularly 

 the process of phagocytosis. Arloing and Cour- 

 mont, and Koger believed that bacteria secrete sub- 

 stances which favor their growth in the body. 

 Eoger observed that an extract of the bacillus of 

 symptomatic anthrax when injected into the rabbit 

 favored infection with this organism. Bouchard 

 spoke of such elements as substances favorisantes. 

 Kruse (Zeiglers Beitrage, xii, 339) also believed 

 that such substances exist and called them collect- 

 ively lytische Sustanzen, Ang riff st off e, oder Lysine. 

 He supposed that their effect was chiefly to neu- 

 tralize the alexins, the name which, at that time, 



2. Cited by Eisenberg, 1. c. 



