460 BACTERIOLOGY. 



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 de- 

 struction of the comma bacillus 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 MetschnikoiF 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 Pfeifi^er as a means of differentiat- 

 ing the cholera spirillum from other suspicious species, 

 for no such bacteriolytic action is observed if species 

 other than the cholera spirillum 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 the cholera 

 spirillum similar to that seen when typhoid bacilli are 

 mixed with serum from typhoid cases, or from animals 

 artificially immunized from typhoid infection or intoxi- 

 cation. (See Agglutinin.) 



General Considerations. — In all cases of Asiatic 

 cholera, and only in this disease, the organism just 

 described can be detected in the intestinal evacuations. 

 The more acute the case and the more promptly the 

 examination is made after the evacuations have passed 

 from the patient, the less difficulty will be experienced 

 in detecting the organism. 



In some cases the organism can be detected in the 



