The gonadotropic activity was assayed biologically with the urine of the two castrated women. The effects of the gonadotropic hormone were found to be different from that of the urine of pregnant women. Using numerous successive extraction of the gonadotropic hormone with the specimens, an efficient extraction was achieved by the addition of acetone to the final concentration of 65 vol. %. The final product was obtained in the form of powder. Koyama's method of hypophysectomy in rats improved to be performed with mature rats. The urinary gonadotropic hormone in the castrated was proved to be hypophyseal from the experiment with hypophysectomized rats.
