LYSINS 87 



moved from a serum by heating the latter to this tem- 

 perature, rendering the serum inactive although it con- 

 tains the specific element or amboceptor. The serum 

 can be made active again by adding more complement 

 in the form of fresh unheated normal serum. This 

 discovery that two elements, one specific and the other 

 non-specific, are necessary for bacteriolysis, was made 

 by Bordet. 



Pfeiffer's Phenomenon. — Our knowledge of bac- 

 teriolysins is dependent largely upon the following 

 experiment carried out by PfeifFer. He injected a 

 suspension of cholera spirilla into the peritoneal cavity 

 of guinea-pigs that had been previously immunized to 

 cholera spirilla, and also into non-immunized guinea- 

 pigs. In the case of the non-immunized animals the 

 bacteria increased in number until they destroyed the 

 animals. In the case of the previously immunized 

 guinea-pigs, examination of the peritoneal fluid from 

 time to time showed that the bacteria quickly died, be- 

 came clumped together in granules, became broken up, 

 and finally were dissolved. Practically, this phenome- 

 non may be made use of in the identification both of 

 bacteria and of specific immune sera. It is especially 

 of value in the identification of cholera spirilla. For 

 this purpose, guinea-pigs previously immunized to chol- 

 era are injected intraperitoneally with the suspected 

 organisms, and the peritoneal fluid examined from 



