TECHNIQUE OF BACTERIOLYTIC EXPERIMENTS. 



121 



The specificity of the bacteriolytic process depends, therefore, on the 

 specificity of the cytophile group, while the complementophile group pos- 

 sesses no or, strictly speaking, only slight specificity; it adapts itself to the 

 complements of very many though not quite all kinds of animals. 



Technique of Bacteriolytic Experiments. 



To determine the occurrence of bacteriolysis there are two methods of 

 procedure; 



1. Pfeiffer's experiment. 



2. The bactericidal plate method. 



I. The Pfeiffer's Experiment. 



The essentials of Pfeiffer's experiment have been described at the begin- 

 ning of this chapter. Briefly, it consists in injecting intraperitoneally into a 

 normal animal, bacteriolytic immune serum mixed with living bacteria. 

 The resulting bacteriolysis is studied microscopically by withdrawing small 

 amounts of peritoneal exudate from time to time. If this experiment is 

 performed with various dilutions of immune serum, and if it be determined 

 at what dilution bacteriolysis fails to occur, then the bacteriolytic titer is 

 evident. 



The details can best be understood by taking a practical example. It is 

 desired to find the bacteriolytic titer of the serum of a patient recovering 

 from typhoid fever by means of the Pfeiff er experiment. 



To accomplish this task the following ingredients are needed: 



1. A strain of bacillus typhosus of known virulence for guinea-pigs. 



2. Patient's serum, sterile, and free from complement. 



3. Guinea-pigs of 250 grams weight. 



A preliminary experiment must be performed in order to determine the virulence of the 

 typhoid strain. 



TESTING THE VIRULENCE OF STRAIN. 



