Wassermann, Neisser and Bruck applied Bordet-Gengou's phenomenon of complement fixation to syphilis in 1906. Since then, their principles have undergone many refinements until to-day the method of complement fixation stands out as a test par excellence for syphilis. The recognition of natural antisheep red cell amboceptor, the provisions against non-specific complement deviation, the use of inactive serum, the refinement of antigen, the cognizance of anticomplementary effects — all have determined the specificity of the Wassermann reaction.
Owing to the difficulties encountered in a reliable performance of the reaction, methods have been devised for the serodiagnosis of syphilis, having for their main objects simplicity and rapidity. These methods are based on precipitation in luetic serums by various reagents.
R. Kraus,1 in 1897, discovered the precipitating action of immune serums by bacterial suspensions; but, as the Treponema pallidum is so difficult of cultivation, no similar method was used in syphilis to