The Augmentary Factor in Animal Sera After Injections of Pituitary Extract.∗

Summary Injections of a gonadotropic extract of sheep-pituitary glands into a horse arid 2 dogs induced the formation in their sera of a factor which augiiientetl three-fold the gonadotropic activity of the extract when tested in immature rats. The augmenting factor had no gonadotropic action in liypophysectomized immature rats, but produced in immature normal rats an effect resembling F.S.H. or synergist. The auginentitig factor, possibly an antihormone to the pituitary gonadtropic antagonist, was present only in the pseudo-globulin fraction of the sera, which fraction also carries the immune bodies and other antihormones.