Variation of Sex Differentiation in Metamorphosing and Newly Metamorphosed Frogs of Rana ornativentris

Abstract

Observations on metamorphosing and newly metamorphosed frogs of Rana ornativentris showed that there is a considerable variation in the body growth and the sex differentiation of the gonads. The environmental water temperature is suggested to be related to this phenomenon. The mode of sex differentiation in amphibians has been classified into three types in relation to the time of metamorphosis (Witschi, 1929), and according to this classification, the mode in Rana ornativentris inhabiting the Niigata district belongs to the semidifferentiated type. It is conceivable, however, that the conception introduced by Witschi has no significant meaning embryologically.