204 THE AMERICAN NATURALIST [Vol. LVI 



its cells develop into true functional eggs ; and by its de- 

 generate structure from its inception in both sexes. 



In a recent paper {Zoologischer Anzeiger, Dec, 1921) 

 Harms describes marked hypertrophy of Bidder's organ 

 following testis removal. He considers that castration 

 of males causes Bidder's organ to develop into an ovary. 

 However, it should be noted that such operated animals 

 with hypertrophied Bidder's organ (ovary according to 

 Harms) retain all their male secondary sex characters, 

 and their normal mating instincts and that these male 

 characters and instincts undergo a normal cyclical de- 

 velopment in such induced ' ' females. ' ' When Harms 

 removed both testes and Bidder's organ the somatic sex 

 characters and instincts failed to develop, showing clearly 

 that Bidder's organ in male toads acts like a testis in 

 maintaining the secondary sexual characters. This is 

 excellent evidence for the writer's view that in male toads 

 Bidder's organ is simply a persisting embryonic male sex 

 gland rudiment and not an ovary. If it is an ovary why 

 should it develop and maintain the secondary sex charac- 

 ters of the male in absence of the testis? 



7. Recent investigators have inclined to the view that 

 this structure is a hermaphrodite gland, i.e., in male 

 toads a rudimentary ovary, in females a rudimentary 

 testis. If this is true then the admission is made that 

 large, senescent, oocyte-like germ cells are not necessarily 

 female cells --the crucial point for which the writer is 

 contending. 



8. Bidder's organ in Bufo corresponds to the larval 

 gonad of frogs which in these forms disappears in the 

 male and is replaced by the definitive testis. In the case 

 of female anurans so far as the writer is aware no one 

 has carried out a thorough investigation of the germ 

 cycle from larval to fully adult life to see whether or not 

 such a degeneration occurs in the female line. In mam- 

 mals and birds such degeneration of the female embry- 

 onic line of germ-cells is quite well established as the 

 work of Winiwarter, Firket and others shows. 



