FURTHER OBSERVATIONS ON THE GONAD-STIMULATING PRINCIPLE OF THE ANTERIOR LOBE OF THE PITUITARY BODY

¹ From the Pharmacological Laboratory, The University of Chicago

1. The gonad-stimulating principle of the pituitary body retains its activity for five months if kept at 4°C. in aqueous solutions at pH 3.7 to 6.4. Alkaline solution of the hormone (pH 7.5) are stable for at least two and one-half months.

2. Purified preparations in aqueous solution (pH 4.9 to 5.4) are destroyed by boiling.

3. Berkefeld filtration of aqueous solutions at either an alkaline or an acid pH does not remove the hormone.

4. No evidence for the separation of the hormone into follicle-stimulating and luteinizing fractions was obtained. The experiments of Fevold, Hisaw and Leonard were not confirmed.

5. A simple method of making preparations free from the posterior lobe pressor principle is described.

6. Gonad-stimulating powders obtained from the pituitary are free from manganese (less than one part in ten million parts of fresh gland). Manganese in total doses of 1.0 to 0.1 mgm. of MnCl₂·4H₂0 causes no precocious sexual development.

7. The difficulties of quantitative assay are discussed.