270 



THE TECHNIQUE OF SERUM REACTIONS 



hour. When complement is then subsequently titrated with 2 such 

 amboceptor units and 0.5 c.c. of 5 per cent red cells, it is usually found 

 that the minimal hemolytic dose of complement lies between 0.2 and 

 0.25 c.c., and in the actual tests twice this minimal hemolytic dose of 

 complement is used with the 2 units of amboceptor. The daily titra- 

 tion of complement frequently shows marked variations even though 



SCHEME FOR WASSERMANN TEST. 



ADAPTED TO ORIGINAL WASSERMANN SYSTEM AFTER SCHEME OF NOGTJCHI. 



O = test tube. 



Place in water bath at 40 C. for one hour, then add to all tubes red blood cells and 

 amboceptor. These are previously mixed so that 2 c.c. contains the equivalents of 

 1 c.c. of a 5 per cent emulsion of sheep corpuscles and 2 units of amboceptor. Again 

 expose to 40 C. If the serum tested is positive, tubes 1 and 3 should show no 

 hemolysis, all the other tubes showing complete hemolysis in one hour. 



the complement is obtained from a number of guinea-pigs. By always 

 using twice the amount which just lakes with 2 units of amboceptor, 

 one keeps the actual amount of complement as nearly as possible 

 constant. 



Obviously one can titrate the strength of the reaction by varying 

 the amount of any one of the three ingredients which primarily enter 



