F. A. E. Crew 173 



The gonad ofBafo is subject to considerable variation. Cerruti figures 

 a Bu/o vulgaris in which he observed, in front of each testis, a Bidder's 

 organ, another piece of testis, another Bidder's organ and histly the fat- 

 body; and in another case, quoted in the lists, in which in place of 

 Bidder's organ there was found in front of each testis an ovary. Knappe 

 describes a case, quoted also in the lists, in which he observed in front 

 of each testis a Bidder's organ, an ovary, another Bidder's organ and 

 lastly the fat-body. King has dealt with such abnormalities at length, 

 and she is of the opinion that the component cells of an embryonic 

 testis or ovary, in response to the stimulus of altered blood supply, can 

 assume the characteristics of a Bidder's organ. It certainly does appear 

 that cells which normally should develop into typical testis or ovary or 

 Bidder's organ can, on occasion, develop into another of these tissues. 



In Cases 34 and 37 the position of the ovarian portion, coupled with 

 the fact that the Bidder's organ was missing, strongly suggests that 

 these had been derived, in part at least, from those cells which normally 

 would have given rise to Bidder's organ. Further, as King points out, 

 as the testis-portion in these cases was shorter than the normal testis of 

 the typical male, it may be assumed that the primordial germ-cells in the 

 anterior part of the germinal ridge, which normally would have developed 

 into spermatic tissue, had also taken part in the formation of the ovary. 

 She suggests that the causal agent, whatever it may have been, must 

 have acted at a very early period in the life-history of the individual, 

 since in the normal toad the cells which develop into Bidder's organ 

 become differentiated when the tadpole is about two weeks old. 



In Cases 33, 35 and 36, an ovary was found between the Bidder's 

 organ anteriorly and the testis posteriorly. This can be interpreted as 

 the condition in which the most anteriorly situated cells of the germinal 

 ridge have developed, as is usual, into a Bidder's organ, those situated 

 posteriorly into a testis, while the cells of the more anterior part of the 

 middle region of the ridge have developed, for some reason or other, 

 into an ovary. In Case 39 one gonad was an ovo-testis with the ovary- 

 portion posteriorly situated. There is in this a strong suggestion that 

 either the forerunners of testis, ovary, and Bidder's organ are normally 

 present in the apparently undiiferentiated primordial germ-tissue, or 

 perhaps, that the foundation primordial germ-cells, in response to the 

 appropriate stimulus, can become any one or all of the three types of 

 adult germinal tissue. 



The cases illustrate the process by which an individual with every 

 female character ultimately comes to possess the typical male organisa- 



