The profound influence of the anterior lobe of the hypophysis on the other endocrine organs, and particularly on the gonads, has been clearly demonstrated during the past few years by numerous experimenters; notably by Smith and his collaborators,1Evans and his co-workers,2Zondek3and Aschheim.4It has been shown that precocious sexual maturity may be induced in immature animals (rats, mice, dogs and monkeys) of both sexes, both by means of frequently renewed transplants of fresh tissue from the anterior lobe and by the administration of extracts prepared from this tissue. This effect is much more rapid and striking in the case of the female; indeed, sucklings may be brought to maturity in from two to four days, as evidenced by great hypertrophy and hyperemia of the uterus; opening of the vagina, with vaginal cellular content characteristic of the estrum, and marked hypertrophy of the ovaries,