§ 4 SEXUAL CYCLE OF BUFO BUFO $ AND $ 135 



logically and statistically. The influence of gonadotrophic 

 mammalian hormones upon these tissues was also studied 

 experimentally. 



e. The oviduct is present in both sexes. In the female it is 

 a tract rich in "sheH"-glands, while, in the male, it is a rudi- 

 mentary tract without any established function, but struc- 

 turally similar to its gonad, the organ of BIDDER. 



Although an extensive literature already exists on the 

 organ of BIDDER, we still lack a wider and more comprehens- 

 ive survey of the entire sexual-endocrine organization of 

 Bufo bufo. We believe we can do this by regarding the organ 

 of Bidder in both sexes as a potential ovary, forming pre- 

 ovulation corpora lutea whose hormone serves to stimulate 

 the oviduct and keep it at the required size and degree of 

 sensitivity. 



Viewed in this light, the sexual-endocrine organization of 

 the female has (a) a potentially female half consisting of a 

 rudimentary ovary and the organ of BIDDER, which forms 

 corpora lutea whose hormone brings the oviduct into the 

 pre-mature state, and (b) a genuinely female half consisting 

 of an ovary forming both mature oocytes and pre-ovulation 

 corpora lutea, whose secretion brings the oviduct from the 

 pre-mature into the estrous stage. 



Similarly, the sexual-endocrine organization of the male 

 has (a) a potentially female half, with a potential ovary, 

 the organ of BIDDER, and a potential oviduct influenced by 

 the corpus luteum hormone from the organ of BIDDER; and 

 (b) a genuinely male half consisting of the testis and the vasa 

 deferentia. After removal of the testis, the organ of BIDDER 

 develops to form an ovary, and the potential oviduct becomes 

 a true oviduct. Thus the original male is changed into a 

 female. In support of this interpretation we may briefly 

 cite the following arguments:— 



f. The significance of the organ of BIDDER and the ovary 

 in the female. 



The weight of the organ of BIDDER reaches a maximum 

 in the spring preceding the first ovulation (Fig. 94 A), and 



