In a comparative study of the Wassermann and Noguchi reactions reported by one of us1 last year, it was stated that by the Noguchi method many positive reactions were obtained with non-specific serums. The same serums, when they were not inactivated, also gave positive reactions by the Wassermann method. When, however, inactivated serum was used in both methods, these non-specific positive reactions disappeared. As a result of this work, in which an alcoholic extract of syphilitic liver was used as antigen in the same proportion in both methods, it was recommended that inactive rather than active serum be used in the Noguchi method.
Noguchi2 has since shown that a non-specific fixation of complement occurs with unheated serum, when protein bodies are present in the antigen extract, and that this non-specific fixation does not occur with inactivated serum. He attributes the non-specific positive reactions, reported by Swift, to