5& EVOLUTION OP THE INFECTIOUS DISEASES 



by bond which have vitally important functions to fulfill; the 

 cells may thus be surcharged with antituberculin. 



Third. That the cells surcharged with antituberculin fix 

 corresponding quantities of tuberculin and that it is on account 

 of this abnormal quantity that the compound of tuberculin and 

 antituberculin becomes pathogenic for the cells. 



Fourth. That the excess of antituberculin confers on the 

 cells and on the organism a non-specific hypersensitiveness to 

 every sort of foreign agent as well as a specific hypersensitiveness 

 to tuberculin. 



Fifth. That granting this is true, the impossibility of an 

 antituberculin immunity such as one finds in d phthena is 

 easily explained. 



Moreover the studies of Koch, Neufeld, Klimmer, Behring, 

 F. Arloing, Chauveau, Calmette and Guerin, Vallee, and 

 others, on vaccination of calves have shown that it is possible 

 to increase the resistance of these animals to experimental 

 tuberculous infection or to natural contagions and although 

 it is impossible to obtain this relative immunity by bacterial 

 secretions, it ought to be obtained by the intervention of 

 bacterial bodies, in other words, by the reactions of the 

 organism against the germ. 



What are these reactions? The study of this question is 

 less advanced than that of the reactions between tuberculin 

 and antituberculin although it has been established with 

 certainty. 



First, that the "preparatory" injections of tuberculous 

 cultures, dead or alive, but not virulent, provoke in the 

 organism the formation of an antibody which agglutinates 

 and precipitates the germs in vitro. 



Second, that the bacteria, dead or alive and avirulent, are 

 more or less rapidly absorbed; that is to say, digested by the 

 organism. 



Third, that if this absorption is complete, acquired immun- 

 ity is of short duration, less than one year. 



Fourth, that if, on the other hand, digestion of living germs 

 injected as a vaccine is not complete there are formed small 

 latent infectious foci. Immunity against one injection or one 

 virulent contagion lasts a long time as the bacteria in these 

 foci live. 



