THE horse pituitary extract AP.118.B induces superovulation in albino does at 12 weeks of age, provided the animals are fed at a high level from birth. Treatment consists of six subcutaneous injections of this pituitary extract at 12-hr. intervals, followed by an intravenous injection of 25 I.U. prolan 12 hr. later. When this treatment was repeated in the same does at 28-day intervals, in 95 per cent of the experiments the ovarian response was poor and ovulation did not occur. Ovulation did occur at sexual maturity, but only the normal number of ova was shed.