Further Studies on the Purification of Mare Gonadotropic Hormone

AMONG THE METHODS used for separating the gonadotropic hormone from pregnant mare serum, the fractional precipitation method of Cartland and Nelson (1) has proved most suitable, in our hands, for consistently yielding fractions of high potency with low nitrogen and solids content. We are now reporting some experiments upon the purification of the hormone obtained from very potent sera from pregnant ponies, testing 100 to 400 rat units1 per cc, together with some studies in which the starting material was obtained from less potent mare sera. The blood was collected from mares pregnant 65 to 75 days. The freshly drawn blood was defibrinated by whipping, and the serum obtained by centrifuging out the cellular constituents. Each batch of serum was worked up immediately; that is, treated according to the Cartland-Nelson process through the first precipitation of hormone by 70% acetone with the exception of two modifications.