COMPLEMENT FIXATION IN GONOCOCCUS INFECTIONS 481 



volume up to about 2 c.c. The tubes are shaken and incubated for one 

 hour at 37 C., when 1}^ units of antisheep amboceptor and 1 c.c. of 

 sheep corpuscle suspension are added to each tube except the corpuscle 

 control. The tubes are gently shaken again and reincubated for an 

 hour or longer, depending upon the hemolysis of the controls, after 

 which the results are recorded. This secondary incubation may be 

 omitted and the tubes placed in a refrigerator overnight and the re- 

 sults read the next morning. Under these conditions hemolysis occurs 

 slowly, and according to some workers in this field the reaction becomes 

 more delicate. 



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

 the serum of a case of gonorrheal arthritis (Fig. 118). 



TABLE 18. GONOCOCCUS COMPLEMENT-FIXATION TEST 



In reading the results the controls are first examined and the test 

 reported as negative, weakly positive, moderately positive, or strongly 

 positive, as the case may be. 



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 

 31 



