No. 644] 



TRANSFORMATION OF SEX 



205 



The writer is of the opinion that it is only by adopting 

 the view advanced here regarding the homologous nature 

 of the larval male gonad of frogs, and Bidder's organ 

 in Bufo, that the problem of sex differentiation in anu- 

 rans can be placed upon a rational basis. The theory 

 accords with the embryological facts, covers the experi- 

 mental finding of Witschi and others, accords with our 

 own cji;ological data in the bullfrog, accords with the 

 embryonic sexual conditions of other vertebrates, i.e., 

 the degeneration of the embryonic line of germ cells in 

 birds and mammals, and lastly furnishes an explanation 

 of Bidder's organ in Bufo. 



The key to the puzzle of sex development in frogs is 

 •simply this: every cell that superficially resembles an 

 ooc}i;e is not necessarily a female cell especially when 

 occurring in an otherwise male individual, and that the 

 larval male gonad of anurans is an organ of Bidder — 

 a rudimentary embrj^onic sex gland with the same sex as 

 the definitive gonad arising out of it. Misinterpretation 

 of oviform hypertrophy and degeneration of racially 

 senescent sex cells has rendered chaotic the problem of 

 sex differentiation in anurans (see Plates 1 and 2). 



Witschi regards the development of certain somatic 

 sex characters such as the Mtillerian ducts as very 

 positive evidence for his theory of sex transformation. 

 He says: 



In males which show a tj-pical development of the testicles, no 

 Mullerian duets of any significance are formed. On the other hand, 

 such animals as first develop ovaries and later undergo the trans- 

 formation of sex, also show regular oviducts; and these continue to 

 grow just up to the time when the transformation of sex begins. 

 This parallelism in the behavior of the Mullerian ducts and the 

 gonads furnishes definite proof that the "eggs" and "ovocytes," 

 described by the writer, are in fact really ^gs and ovocytes and that 

 the transformation of sex is a well-established fact. After the trans- 

 formation of S€x, when the ovocytes have disappeared, the Mullerian 

 ducts begin to shrink but they do not disappear completely, etc., etc. 



The following data shows that in reality such so-called 

 parallelism in the behavior of the Miillerian ducts and 



