WASSERMANN AND OTHER COMPLEMENT FIXATION TESTS 253 



comparison with the original Wassermann, through long series of tests, has even- 

 tually established the superiority of the Wassermann test. 



The experience of years of universal application of the Wassermann test 

 has naturally amplified knowledge of the different elements entering into it and 

 established certain facts that have permitted slight changes in technique, in no 

 case basic, but such as to a slight degree simplify the performance of the test 

 as the introduction of alcohol, ether and acetone extracts of tissue for antigen, 

 the reduction of the quantities used in the test to one-half the original volumes, 

 the reduction of incubation from 2 hours to i, and the introduction of quantita- 

 tive determination of the syphilitic reaction. 



The quantity of any one of the five substances entering into a complement 

 fixation test must bear a proportionate relation, within certain limits, to all the 

 others. Theoretically, the larger the quantity of patient's serum used the 

 greater the possibility of detecting syphilitic antibodies when present in small 

 amount. The amount of human serum that may be used is limited, however, 

 by the irregular but frequent presence in human serum of substances, not related 

 to syphilis, which tend to deviate complement. The proportion of human 

 serum to other substances in the test as laid down by Wassermann is such that 

 this non-specific deviation of complement cannot cause positive reaction in 

 negative cases. Human serum also may contain substances which can 

 hemolize red cells, without the presence or aid of complement; in the propor- 

 tion of human serum to red cells used in the Wassermann test this effect is 

 not observed, but if four or five times as much human serum is used it is 

 frequently noted, this would give a negative reaction (hemolysis) even though 

 the serum was positive, therefore, blood serum cannot be examined as spinal 

 fluid is. When serum is not inactivated before subjecting it to a complement 

 fixation test, a negative serum frequently shows a positive reaction; this is 

 especially true when the antigen contains protein. 



A reduction of the quantity of human serum used to make a Wassermann 

 test necessitates a proportionate reduction in the quantity of all the other sub- 

 stances; the only advantage in such a procedure is a reduction in labor and ex- 

 pense which necessarily is associated with a greater probability of error, because 

 no matter how careful a worker may be the smaller the quantities with which he 

 works the greater the proportion of error in measurements; in addition to this, 

 the Wassermann test seems to be a chemical reaction of colloidal nature and 

 this further accentuates the danger of error in greatly reducing the quantities 

 used in making the test. 



A comparatively small amount of experimentation will convince one that 

 human serum should be inactivated and that not less than o.i cc. nor more than 

 0.2 cc. should be used. 



The sensitiveness of the Wassermann test, the power to show distinct posi- 

 tive reactions with human serum containing a very small quantity of specific 

 amboceptor, can be increased by using amounts of antigen but slightly less than 

 the minimum anticomplementary quantity. 



The advantage so gained in obtaining positive reactions on syphilitic serum 



