Abstract
1. Antibody produced in the horse migrates as a new serum component between the beta and gamma components, whereas rabbit antibody is electrophoretically identical with the gamma globulin component of the serum. 2. In rabbit and monkey antisera the percentage of antibody in the serum and in the gamma globulin fraction can be determined by integration of the electrophoresis diagrams of unabsorbed and absorbed sera. Antibody solutions of high purity can be obtained by electrophoretic isolation of the gamma globulin of rabbit antisera in which the percentage of antibody to total gamma globulin is high. 3. The isoelectric points of pig, cow, horse, and rabbit antibodies have been determined. 4. In horse sera prolonged immunization is accompanied by the formation of another antibody component of lower mobility.