92 APPLIED IMMUNOLOGY 



suitable amounts of complement. In experimental 

 and diagnostic work, the rabbit is the animal usually 

 employed for the production of specific hemolytic 

 serum. By three or four intraperitoneal or intraven- 

 ous injections of suitable quantities of washed sheep's 

 corpuscles into the rabbit at intervals of 3 or 4 days, 

 the rabbit's serum will become so highly immunized 

 that it will, in 1-1000 or greater dilution, hsemolyze 

 an equal quantity of 5 per cent, suspension of sheep's 

 corpuscles in the presence of a sufficient amount of 

 complement. It has been found that complement is 

 present in varying amounts in the blood-serum of dif- 

 ferent animals, but that the serum of the guinea-pig 

 is most constant in this respect. So in order to insure 

 the presence of a definite amount of complement, the 

 immune hsemolytic serum (rabbit) is heated at 56° C. 

 to destroy the complement present, and a definite 

 amount of fresh guinea-pig serum afterwards added. 

 The technic of the preparation and titration of specific 

 hsemolytic serum will be given under the description of 

 the Wassermann reaction. 



The Bordet-Gengou Phenomenon 



Bordet and Gengou were the first to employ the 

 complement-fixation reaction in the diagnosis of spe- 

 cific infections. Since the phenomena of bacteriolysis 

 and of haemolysis each depend upon the presence and 



