Abstract
1. Pertussis antitoxic rabbit serum was prepared by a series of subcutaneous injections of sonic extract of pertussis phase I bacteria.
2. A specific agglutinin, antitoxin and mouse protective antibody existed in Cohn's fraction II. These antibodies could not be separated from each other by chemical and physical methods.
3. By zone electrophoresis these three antibodies were found in the γ-globulin fraction in rabbit sera.
4. In fractionation of pertussis immune horse sera by cold ethanol or zone electrophoresis, agglutinins were concentrated in both β-and γ2-globulin fractions, the antitoxin in γ2-globulin fraction, but mouse protective antibody could not be demonstrated quantitatively.
