1. Ovulation and oviposition can occur in Xenopus laevis without the mating reflex.
2. Conversely, the mating reflex is shown to occur before intraoviducal ovulation has taken place.
3. Females with atrophied ovaries which may yet respond to the ovulating principle in the extracts fail to evoke the mating reflex in the males.
4. This is to be regarded as additional evidence of the fact that the extracts probably exert their effect on the mating reflex through the intermediation of the normal gonads.
5. The failure of females with atrophied ovaries to couple although intra-oviducal ovulation may have occurred suggests that a second ovarian mechanism, which is present in the normal but not in the atrophied ovary, is necessary for the establishment of the mating reflex.