Like all other procedures concerned with the treatment or diagnosis of disease, the complement-fixation reaction as applied to the diagnosis of syphilis has been studied extensively, as a result of which the method has experienced decided modifications as compared to the technic originally described by Wassermann, Neisser, Bruck and Detre.
In spite of the large amount of work which has been done, however, we are still in ignorance as to the exact nature of the substance or substances reacting in the test and the mechanism of their production; in fact, as has been summed up by Kolmer,1 all that is definitely known of the reaction is that while lipoidal extracts (antigens), as well as normal and syphilitic serums, may separately absorb or fix small amounts of complement, a mixture of a suitable extract and a syphilitic serum is capable of fixing large amounts of complement.
If little advance has