MICROSPIRA COMMA. 471 



by repeated injections of non-fatal doses of dead cul- 

 tures (cultures that have been killed by the vapor 

 of chloroform or by heat). He also demonstrated 

 that animals so immunized possess a specific germi- 

 cidal action toward microspira comma i. e., if into 

 the peritoneal cavity of an animal immunized from 

 Asiatic cholera living organisms be introduced they 

 will all be destroyed (disintegrated) within a rela- 

 tively short time. Furthermore, if the serum of an animal 

 immunized from cholera be injected into the peritoneal 

 cavity of another animal of the same species, but not so 

 protected, and immediately afterward living cholera spir- 

 illa be introduced, a similar disintegration and destruction 

 of the bacteria will also result. He shows that a more or 

 less definite relation exists between the amount of 

 serum and the number of organisms introduced. Such 

 a destruction of microspira comma by the serum of an 

 immunized animal does not occur outside the animal 

 body that is, it cannot be demonstrated in a test-tube, 

 unless, as Bordet has demonstrated, it- be perfectly fresh 

 from the animal body, or, as Metschnikoff has shown, 

 there be added to it a small quantity of fresh serum 

 from a normal guinea-pig. The specificity of this reac- 

 tion is suggested by Pfeiffer as a means of differentiat- 

 ing the cholera spirillum from other suspicious species, 

 for no such bacteriolytic action is observed if other 

 bacteria be introduced into the peritoneal cavity of 

 animals immunized from Asiatic cholera. 



Pfeiffer has further demonstrated that the serum of 

 animals artificially immunized from Asiatic cholera has 

 an agglutinating effect upon fluid cultures of microspira 

 comma similar to that seen when typhoid bacilli are 



