TYPHOID FEVER. 381 



Kolle, cannot be separated from the bodies of the bacilli 

 producing it. 



Animals can easily be immunized to this bacillus, and 

 then, according to Chantemesse and Widal, develop in 

 their blood an antitoxic substance capable of protecting 

 other animals. Stern L has also found that in the blood 

 of human convalescents a substance exists which has a 

 protective effect upon guinea-pigs. His observation is in 

 accordance with a previous one by Chantemesse and 

 Widal, and has recently been abundantly confirmed. 



The immunization of dogs and goats by the introduc- 

 tion of increasing doses of virulent cultures has been 

 achieved by Pfeiffer and Kolle 2 and by LofBer and Abel. 3 

 From these animals serums were secured not exactly an- 

 titoxic, but anti-infectious or auti-microbic in operation, 

 and possessed of marked specific germicidal action upon 

 the typhoid bacilli when simultaneously introduced into 

 the peritoneal cavity of guinea-pigs. 



The action of the typhoid serum is specific, and exerts 

 exactly the same action upon the typhoid bacilli as the 

 cholera serum exerts upon the cholera spirilla, killing 

 and dissolving them (Pfeiffer' s phenomenon). 



So far, no serum has been produced that is efficacious 

 in human medicine. 



The specific reaction of the serum can be used to dif- 

 ferentiate cultures of the colon and typhoid bacilli, the 

 typhoid bacilli alone exhibiting the specific effect of the 

 typhoid serum. 



Christophers 4 found that the serum from typhoid 

 patients occasionally caused agglutinations in cultures 

 of the colon bacillus, but concludes that this does not 

 lessen the specificity of the reaction, as there may be 

 two combined specific actions of these serums. Experi- 

 ments on rabbits established that typhoid and colon 

 serums could be produced, each specific in its agglutin- 



1 Zeitschrift fur Hygiene, xvi., 1894, p. 458. 2 Ibid., 1896. 



3 Centralbl.f. Bakt. u. Parasitenk., Bd. xix., No. 23, p. 51, Jan. 23, 1896. 

 * Brit. Med. Jour., Jan. 8, 1898. 



