FIXATION OF COMPLEMENT 143 



tion with a fresh known negative and a known positive 

 senun; the positive showing the true antigenic dose, 

 and the negative the highest quantity of antigen which 

 will allow complete hsemolj^sis ; in the actual test this 

 large quantity of antigen is placed in one tube and 

 one-half the quantity in a second tube; (4) comple- 

 ment 0.1 c.c. of a dilution 1 to 10; (5) amboceptor, 0.1 

 c.c. representing twice the lowest quantity that will 

 completely hsemolyze 0.1 c.c. of the cell suspension 

 with 0.1 c.c. of complement in one hour; (6) sheep's 

 red blood-cells (5 per cent, suspension), 0.1 c.c. In- 

 cubation is made for one-half hour at 37° C. in a 

 water-bath or for one hour in dry heat, before and 

 after the addition of the hsemolytic system. 



The technic on which we have learned to place the 

 greatest reliance is essentially that utilized by us in 

 the performance of the Wassermann reaction, merely 

 substituting the gonococcus specific antigen for the 

 syphilitic lipotropic antigen, employing always the 

 carefully standardized single complement unit and 

 the routine standardization of antigen and ambocep- 

 tor (see Table of Test Reactions). 



Antigens, — The necessity of a polyvalent antigen 

 is indisputable, presumably owing to the diversity of 

 the strains of the gonococcus. The only question of 

 importance is, how may this antigen be prepared to 

 the best advantage? Schwartz and McNeil in their 

 latest communication say that the " various strains of 



