118 APPLIED IMMUNOLOGY 



majority of workers employ excessive doses of comple- 

 ment and double or treble the smallest amount of 

 amboceptor necessary to produce complete hemolysis 

 of the corpuscles. The only possible reason for the 

 use of such excessive doses of the two reagents is 

 to overcome the effect of fixation of a slight amount 

 of complement, non-specifically, by the patient's 

 serum and the antigen alone, and to replace the com- 

 plemental power lost in the incubation. This empiri- 

 cal method is responsible in part for negative results 

 in positive cases. By the method in use by us, we 

 are enabled to accurately allow sufficient complement 

 for the overcoming of any non-specific fixation by 

 serum and antigen alone, and also to make up for 

 the complement lost during incubation, and at the 

 same time use in the test proper not more than one 

 hemolytic unit. Previous to titration of comple- 

 ment with hemolytic amboceptor and corpuscles, the 

 complement is first incubated with one dose of antigen 

 and 0.1 c.c. of a mixture of several non-syphilitic 

 sera. This is done for the reason that a slight amount 

 of complement is fixed under these conditions by the 

 serum and antigen, and we are thus sure of allowing 

 for this slight non-specific fixation in the test itself. 

 Different sera present variations in the amount of 

 complement they are capable of absorbing in this 



