No. 644] TRANSFORMATION OF SEX 



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outstrip in development the cells of the definitive gonads 

 located posteriorly. 



2. The cells of Bidder's organ extremely early in de- 

 velopment undergo a precocious and abortive matura- 

 tion cycle and l>ecome senescent and degenerate oocyte- 

 like structures when the germinal elements of the func- 

 tional gonads have barely started to multiply to form 

 the definitive glands. This occurs in individuals of both 



3. The larval maturation cycle such as occurs in the 

 bullfrog, and in other anurans, throughout the entire 

 larval gonad is confined to Bidder's organ in Bufo, and 

 the changes occurring in this structure do not affect the 

 normal developmental cycle of the definitive germ glands 

 behind. 



4. The so-called transformation of female animals into 

 males, claimed by Witschi and others to be the normal 

 course of development in frogs, does not occur in toads. 

 Why? Because in Bufo, the definitive gonads are from 

 the beginning located posterior to Bidder's organ, and 

 it is not necessary in order that they may develop that 

 this structure degenerate and disappear as is the case 

 in frogs where the definitive testis starts development 

 as a core within the pro-testis or Bidder's organ, neces- 

 sitating its complete destruction. 



5. Few have ever claimed that sex in toads is labile 

 and easily reversed by environmental influences. Why? 

 Because the sex of the definitive gonads is definitely fixed 

 and clear cut at an early stage of life. The separation 

 of Bidder's organ and the gonads has precluded the 

 possibility of confusing the pro-gonad and the definitive 

 gonad. 



6. Bidder's organ is merely a persisting embryonic 

 gonad whose cells have undergone oviform degeneration. 

 It is not a rudimentary ovary except in female animals. 

 This is indicated by its presence in both sexes in toads; 

 its presence in Spengel's case of true hermaphroditism; 

 by the fact that neither in male or female of toads do 



