172 Sex-Reversal in Frogs and Toads 



These characters do not become at all obvious while the individual 

 is still young, and the female characters are, for the most part, negative 

 in nature. Assuming that there is some intimate relation between the 

 primary and secondary sexual characters, a review of the cases suggests 

 that the super-imposition of male upon female secondary sexual cha- 

 racters is a simple matter in the Anura. The presence of patches of 

 ciliated epithelium upon the peritoneum round about the suspensory 

 ligament of the gonad does not interfere with the assumption of the 

 male characters which are developed in quite different situations. The 

 wartiness of the skin is a seasonal phenomenon and only occurs in the 

 presence of functioning ovarian tissue. 



It has been shown that the development of spermatic tissue upon 

 the inner border of a gonad, which previously had every appearance of 

 an ovary, occurs at an early stage in the life-history of the individual, 

 and that coincidently with its appearance the ovarian tissue begins to 

 degenerate. If, then, the female secondary sexual characters are not 

 developed to any extent, until the normal female is well-matured, the 

 development of the spermatic tissue in these abnormal individuals and 

 the consequent destruction of the ovarian tissue will prevent the as- 

 sumption of the female characters. 



The degree of development of these characters bears no relation to 

 the amount of germinal tissue present, but this tissue must be healthy 

 and functioning. A small amount of healthy spermatic tissue is asso- 

 ciated with well-defined male secondary sexual characters, although in 

 the individual there is a greater amount of ovarian tissue which is 

 pathological. It is seen that the exhibition of the male sex-hormones is 

 not attended by the development of any structure which is not repre- 

 sented cmbryologically in the normal female, and that as in the case of 

 the accessory reproductive apparatus, the hormones act by inhibition 

 and stimulation of normal embryonic rudiments. 



The cases of abnormality in Bufo, Bomhinator, Pelohates and Hyla 

 are too few to permit of a similar treatment to that adopted in the case 

 of Rami. They are, however, exactly similar in their nature and there 

 can be no doubt that the conditions found are, with minor differences, 

 identical with those described in Rana. 



The relative position of ovarian and spermatic tissues in an ovo-testis 

 is somewhat different, in that the ovarian tissue is placed anteriorly and 

 the spermatic posteriorly. Further, it would seem that the comparatively 

 smaller amount of spermatic tissue is associated with the assumption of 

 male, secondary, sexual characters in the case of Ba/o than in Rana. 



