Specific Molecular Valence of Antigen and Antibody

Evidence bearing on the molecular valence of antigen and antibody is presented and discussed. Antigenic proteins having a molecular weight of about 35,000 seem to have a minimal functional valence of 5, with an upper limit less than 30; larger molecules can have much higher valences, plausibly in proportion to their surface. Much speculation and an as yet inadequate body of experimental data indicate that ordinary antibody is univalent, or perhaps divalent.