508 



THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



yields particularly delicate reactions and intensifies the degree of specific 

 fixation of complement. 



The following table is an example of a gonococcus fixation test with 

 the serum of a case of gonorrheal arthritis (Fig. 121). 



TABLE 18. GONOCOCCUS COMPLEMENT-FIXATION TEST 



In reading the results the controls are first examined and should show 

 complete hemolysis; the test is reported as negative if all tubes are 

 hemolyzed, weakly positive if the largest dose only of serum (0.2 c.c.) 

 shows inhibition of hemolysis, moderately positive if the 0.1 and 0.2 c.c. 

 doses of serum show inhibition of hemolysis, and strongly positive if 

 the 0.05, 0.1, and 0.2 c.c. doses of serum react positively. 



The test may be conducted with but one dose of serum, namely, 

 0.2 c.c. with the antigen and 0.2 or 0.3 c.c. in the serum control tube, 

 after the manner of the original Wassermann reaction; in this case the 

 readings are made after the usual +, + +, + + +, and + + + + 

 method (see page 464) . 



GONOCOCCUS FIXATION TEST, USING ONE-TENTH THE USUAL AMOUNTS 



This technic is employed for purposes of economy, especially since 

 the antigen is likely to be expensive. Otherwise the method is less 



