62 EVOLUTION OF THE INFECTIOUS DISEASES 



be a question of an immunity from anti tuberculin but since 

 it is shown that tuberculosis can heal spontaneously and 

 that a certain relative immunity may be obtained by bac- 

 terial vaccination we should necessarily assume that a 

 bacterial therapy and a specific chemotherapy should very 

 appreciably aid the destruction of the bacteria. Serum 

 therapy would be applicable only in the stages of the disease 

 during which one could establish the absence in the organism 

 of antibody in excess. 



TYPHOID FEVER. 



We know that completely digested albumins, that is to 

 say, those which are transformed to their amino-acids are 

 not antigens, while albumins themselves as well as all incom- 

 pletely digested compound are antigens. We must suppose 

 that in infections of intestinal origin bacteria as well as the 

 products of bacteria can resist digestion and can penetrate 

 into the cells and capillaries of the intestinal mucosa and 

 that only the individual and the species unable to digest the 

 bacteria and reduce them to amino-acids can be infected in 

 this way. It is at present not possible to follow all the phases 

 of the pathogenicity of typhoid fever in man, but it can be 

 done in paratyphoid fever of young rodents and the patho- 

 genicity can be represented as follows : 



Bacteria enter by the mouth, are in large part destroyed 

 in the stomach but the products of this destruction are not 

 completely digested and pass with the surviving bacteria 

 into the intestines where these latter can multiply until the 

 bacterial products which resist intestinal digestion are in 

 part absorbed by the cells of the mucosa. 



This primary absorption determines the formation of 

 more or less severe areas of congestion analogous to those 

 which are observed when a small quantity of dead bacteria 

 are introduced under the skin. This congestion favors in 

 its turn the penetration into the mucosa and into the capil- 

 laries of fresh quantities of bacterial products and even of 

 living bacteria. The result is that the severity of the con- 

 gestion is increased. 



