126 BACTERIOLYSINS AND HEMOLYSINS. 



cance of phagocytosis. Pfeiffer maintained that bacteriolysis was the most 

 important protective weapon of the immune organism against bacterial in- 

 vasion. According to Metschnikoff and his followers among whom Bail 

 in particular must be mentioned, bacteriolysis in the abdominal cavity is only 

 an exceptional phenomenon (test-tube experiment in vivo) ; its occurence is 

 made possible by the circumstance that the abdominal cavity is as a rule 

 almost free of wandering cells, and that the few which are present are so 

 injured by the severity of the infection, that they disintegrate. If their 

 number increases, bacteriolysis does not occur, or at least is only slight. 

 Likewise, bacteriolysis is incomplete in the presence of cells, for instance in the 

 blood, spleen, liver and subcutaneous tissue, etc. 



A detailed consideration of this much mooted problem does not fall 

 within the compass of this book. It is sufficient to have pointed out the 

 great questions of fundamental significance which hinge upon the discussion 

 of the Pfeiffer experiment, questions which concern the essential features of 

 antibacterial immunity. It can be readily understood, therefore, why the 

 phenomenon of bacteriolysis has been so much studied, although its practical 

 significance is only limited. 



The Pfeiffer experiment can be used in the differentiation of 

 The Practical bacteria as well as in the demonstration of bacteriolysins in 

 Application of serum. It serves as a control for the agglutination reaction. 



Pfeiffer and Kolle, Briefer and others, have used bacteriolysis as a 

 Experiment. 



method of estimating the immunity obtained by active protective im- 



* munization against cholera and typhoid in man. It must, however, be 

 questioned whether it is admissible to draw conclusions as to the degree of active im- 

 munity from the height of the bacteriolytic titer of the serum, inasmuch as animals 

 are found which possess no active immunity and still have sera of high bacteriolytic 

 powers. 



The most important practical use of the Pfeiffer experiment lies in the identi- 

 fication of suspected cholera cultures. In Germany, the Pfeiffer test made 

 with the vibrios obtained in pure culture from the suspected patients, is 

 required for the official diagnosis of the first cases of cholera. 



The serum used for this purpose should be at least strong enough in 

 amounts of 0.0002 c.c. to cause the disintegration of the bacteria in one 

 hour, when a mixture of one loopful of an eighteen-hour agar culture of 

 cholera with i c.c. of nutrient bouillon is injected into the peritoneal cavity 

 of a guinea-pig. 



For this experiment four guinea pigs of 250 grams weight are used. 



