Among the several methods suggested for the titration of antimeningococcus serum, complement fixation was first recommended by Kolle and Wassermann (1). They estimated that a serum to be valuable for treatment should inhibit hemolysis in a dose of 0.001 cc. Other writers, however, chiefly Krumbein and Diehl (2) and St. Baecher and Hachla (3) claimed that this method of testing may lead to erroneous results. Indeed, according to Neufeld (4) and Neufeld and Händel (5) the complement fixing antibodies are quite independent of the bacteriolytic amboceptors and do not necessarily bear any relation to the therapeutic value of the serum.
A similar view has been held by American investigators. Titration of the bacteriotropic power of the serum according to the method of Neufeld as modified by Jobling and Lamar was accepted by Flexner. The laboratories of this country adopted the bacteriotropic method as the most rational of the tests since it was believed to imitate the mode of action of the serum therapeutically.