1. Seasonal changes in the ovaries of Xenopus laevic (the South African clawed toad) are described.
2. Degenerative changes in the large mature central ova occur more rapidly as a result of hypophysectomy than as a result of captivity.
3. The suggestion is made that the pituitary may be concerned with the maturation of ova in Xenopus laevis.
4. Hypophysectomy results in severe arteriosclerotic changes in the ovarianb blood supply as early as 4½12 months after the operation. Control animals show no such changes.
5. The histological changes observed in the ovaries after hypophysectomy, whether total or partial, are probably due to the removal of the anterior lobe alone.