A Model for the Regulation of Antibody Synthesis by Serum Antibody**This work was done under the sponsorship of the Commission on Immunization of the Armed Forces Epidemiological Board and was supported in part by the U. S. Army Medical Research Development Command, Department of the Army, under research contract DADA 17-69-C 9177, in part by U. S. Public Health Service Grant AI-0834, and by the National Science Foundation Grant GB-7473-X.