SEX-REVERSAL IN FROGS AND TOADS. A REVIEW 

 OF THE RECORDED CASES OF ABNORMALITY 

 OF THE REPRODU(JTIVE SYSTEM AND AN 

 ACCOUNT OF A BREEDING EXPERIMENT. 



By F. A. E. CREW. 



{Papers from the Animal Breeding Research Department, 

 The University/, Edinburgh.) 



(With Twenty-three Text-figures.) 



The abnormalities which have been recorded can be so tabulated 

 that the first case most nearly approximates to the normal female and the 

 last the typical male, with respect to the nature of both primary and 

 secondary sexual characters. Thus arranged, it is seen that the cases 

 furnish an almost complete series of gradations which range from an 

 individual almost completely female, to one almost completely male, and 

 that the conditions found readily appear to be merely graded stages of 

 a single process. 



A. RANA. 



Division I. Those Cases in which the Secondary Sexual 

 Characters were not Typically Male. 



Group A. Those cases in whicJi, on inspection, one gonad was an 

 ovary and the other an ovo-testis. 



Sub-group 1. The ovary was normal in appearance. 



1. Bourne. R. temporaria. Adult. Secondary sexual characters 

 were not described. 



Right gonad. An ovary. 



Left gonad. An ovo-testis. The larger ovary-portion bore along the 

 anterior half of its inner border the smaller testis portion. 

 ■ Vasa efferentia could not be observed. 



Seminal vesicles not present. 



Miillerian ducts well-developed. 



On section. Ovary-portion of the ovo-testis contained well-developed 

 ova; testis portion contained motile spermatozoa; and there was no 

 distinct line of separation between ovary- and testis-portions. 



