1. Application of the quantitative agglutination procedure to hemolytic streptococci and their antisera is shown to yield values indicative of the antibody content of the antisera in weight units.
2. Estimations are given of type-specific and group-specific antibody in a number of antisera.
3. An incomplete analysis is given of the antigenic components and antibodies involved in the agglutination.
4. Adaptation of the experimental conditions to a simple qualitative type determination of hemolytic streptococci is suggested.