N'o. 644] TRANSFORMATION OF SEX 



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males, disappears after two years in females, and is an- 

 terior to the functional gonads. In frogs it forms the 

 outer husk of the germ gland enclosing the centrally de- 

 veloping functional testis and may or may not show the 

 oviform type of degeneration, e.g., R. catesbeicma. 



If sex is so labile in tadpoles and young frogs, and 

 females so readily transform into males under environ- 

 mental stimuli, why is it that such sex reversals do not 

 occur in adult frogs after the degeneration of the pro- 

 testis and the formation of the definitive testis has oc- 

 curred? All investigators are agreed that the sex ratio 

 of adult frogs of all species reported is approximately 

 50-50. If environment (ever changing in the same lo- 

 cality, and never the same in different regions), plays 

 such an important sex transforming role, why do male 

 tadpoles never transform into females — all investigators 

 agree that they do not. Why do only fifty per cent, of 

 the so-called larval females transform into males if they 

 were not zygotic males from the beginning, and why do 

 not all female frog larvae transform into males instead 

 of only fifty per cent, if such transformation is possible! 

 Appeal cannot be made to Professor Hertwig's well- 

 known late fertilization experiments because in these ex- 

 periments the influence of the over-ripeness of the egg 

 upon the zygotic conditions determining sex are unknown. 

 Hormones! To date there is no positive evidence that 

 such secretions have ever actually changed a female germ 

 cell into a functional male germ-cell. 



Cases of hermaphroditism in adult frogs are thought 

 by some to furnish evidence of a sex transformation in 

 frogs. However, true hermaphroditism in adult frogs is 

 as rare a phenomenon as it is in mammals when we con- 

 sider the few recorded cases, and the enormous number 

 of frogs annually dissected the world over. Crew ('21), 

 Journal of Genetics, Vol. II, no. 2, has summarized the 

 recorded cases of abnormal sexual organs in frogs and 

 states that there are forty cases. To this number should 

 be added a recent case described in the bullfrog, making 



