1. Removal of the whole pituitary gland of Xenopus laevis or of the anterior lobe alone is accompanied by
(a) reduced food intake,
(b) diminished growth of the body as a whole,
(c) retrogression of the gonads in both sexes.
2. Since there is no significant reduction in the main fat reserves of the body (corpora adiposa) the retrogression of the gonads is not the direct result of reduced food intake at an all-round lower metabolic level.
3. Since the reduction of food intake is proportionately much greater in females than in males, the metabolic demands of the gonad seems to be the controlling agency of food intake.
4. The relatively greater reduction of growth rate in females is due to the large bulk of the ovaries coupled with the fact that ovarian retrogression accompanies the lowering of growth in the rest of the body.
5. Since the food demand of the active ovary is far in excess of the minimum requisite for body growth, the results of this enquiry provide additional confirmation for the view that seasonal variations of food supply are mainly responsible for seasonal variations in the condition of the ovaries of Xenopus in its natural habitat.
Beit Memorial Research Fellow