PRACTICAL APPLICATIONS OF METHOD 203 



added to each tube. 18 If the antigen is suitable in that it does not 

 fix alexin by itself or in the presence of normal serum, hemolysis 

 will result in all of the tubes of series A. If it is suitable in that it 

 fixes in the presence of syphilitic serum, the tubes in series B will 

 show no hemolysis ; if there is slight hemolysis in B 1, it is inferred 

 that 0.05 c. c. of the antigen is insufficient, and the smallest amount 

 (0.1 c. c.), which completely fixes 0.1 c. c. of alexin in the presence 

 of the positive serum, is the quantity used. Again the antigen may 

 be able to cause hemolysis by itself if used in too large amounts. If 

 this is the case in tube B 4, then this antigen is suitable only in 

 amounts varying between 0.1 c. c. and 0.2 c. c. 



The titration is done with varying quantities because too little 

 antigen might fail in fixing the alexin, even if the serum were posi- 

 tively syphilitic, whereas too much antigen might possess alexin-fix- 

 ing properties in itself, even in the presence of normal serum, or 

 possibly without any serum at all, an attribute which is not uncom- 

 monly possessed by lipoidal extracts. 



It is thus seen that Wassermann reactions can be carried out 

 with antigens which do not contain extracts of syphilitic lesions or 

 of the micro-organisms which give rise to syphilis. This fact alone 

 would exclude the possibility of considering the fixation of comple- 

 ment as at present carried out in the Wassermann reaction as being 

 due to a specific antigen-antibody union. 



This conclusion is strengthened by the recent discovery that a 

 specific antigen prepared from cultures of SpirocJiwta pallida cannot 

 be successfully used in diagnostic Wassermann tests. The first in- 

 vestigations of this kind were made by Schereschewsky, 19 who used 

 as antigen extracts of mixed cultures in which the spirochete was 

 present ; his results were inconclusive, l^oguchi 20 later investigated 

 this phase of the problem, preparing his antigens by the extraction of 

 pure cultures and of syphilitic rabbit testicles in which the spirochetes 

 were very profuse. He found that positive tests with such an antigen 

 were obtained only in isolated cases of prolonged syphilis which had 

 been thoroughly treated, and that the ordinary Wassermann reaction, 

 as obtained in active cases, is not due to antibodies which combine 

 specifically with the pallida antigen. Craig and Nichols 21 also have 

 found that cases of untreated syphilis which gave positive reactions 

 with syphilitic liver extracts gave absolutely negative results when 

 culture antigens were used. 



18 Tube "5" is the antigen control which shows that the antigen in large 

 amounts is neither anticomplementary nor hemolytic by itself. It is well, in 

 addition, also to test out various amounts of the antigen and alexin, without 

 either normal or syphilitic serum, to determine the largest amount of antigen 

 which, by itself, is devoid of the actions mentioned above. 



19 Schereschewsky. Deut. med. Woch., 1909, p. 1653. 



20 Noguchi. Journ. A. M. A., Vol. 58, 1912. 



21 Craig and Nichols. Journ. of Exp. Med., Vol. 16, 1912. 



