302 



BACTERIOLOGY 



A glance at the graphic representation of this reaction at 

 once also suggests the means of identifying unknown but 

 suspected antigens. Thus, for instance, if in both series we 

 have the same amboceptors and complement but different 

 antigens, one being specifically related to the amboceptor, 

 the other not, plainly we will have a result similar to that 

 obtained in the first series after the incomplete hemolytic 

 system is added that is, there will be no hemolysis in the 

 tube in which antigen and amboceptor are specifically 

 related, for here all free complement will be fixed on the 

 other hand in the tube in which the antigen is not so related 

 to the amboceptor complement cannot be so fixed and it, 

 therefore, as in the first experiment, remains free to complete 

 the hemolytic system. The reaction may be expressed 

 graphically as follows : 



FIG. 63 

 SERIES I. 



= Plague antigen. 



= Plague amboceptor. 



= Complement. 



Factors united. 



FIG. 64 

 SERIES II. 



= Unknown antigen. 



Plague amboceptor. 



: Complement. 

 No union possible. 



Washed corpuscles and inactivated hemolytic immune serum now added 

 to each mixture. 



In the second application of this test observe that the 

 unknown antigen used in Series II is not of the nature of 



