L. umbratuspituitary glands were partially separated by means of preparative polyacry‐lamide electrophoresis and chromatography on DEAE‐cellulose and Sephadex G‐50. Eight fractions were obtaìned and it was found that fraction 1 contained potent adrenocorticotropic stimulating activity, with a molecular weight in the region of 6000. Fractions 3 and 4 contained potent gonadotropic and a lesser degree of exopthalmic producing activity, with molecular weights in the region of 14 000 to 20 000. Fraction 6 displayed pigeon‐crop stimulating activity, with a molecular weight above 30 000. Fractions 7 and 8 displayed M.S.H. and vasopressinoxytocic activity respectively, with a molecular weight in the region of 5500–6500. Fractions 2 and 5 could not be identified. The fractions seemed to be glycoproteins and the results are discussed in relation to previou