210 THE AMERICAN NATURALIST [Vol. LVI 



the fully fonned testes are present, and the seminal ves- 

 icles are absent or rudimentary in the males of many 

 frog species, and exceedingly well developed in others. 



In the few cases reported of true lateral hermaphro- 

 ditism in adult frogs there is not always a developmental 

 correlation of the Miillerian ducts with the gonad of the 

 same side. Crew ('21), {Journal of Genetics, Vol. II, 

 no. 2) has summarized the known cases of sexual ab- 

 normality in amphibians see Figs. 7, 8, 9, 12, 14, and 

 16 of this paper, also the report of cases 21, 22, 23, 24, 

 and 39. These are exceptions to any rule of develop- 

 mental correlation. In several cases. Figs. 25 and 31, 

 the ducts are quite as well developed in total absence of 

 ovarian tissue as when such is present in large amounts, 

 this, of course, being the normal condition in Rana pipi- 

 ens. Crew also gives a list of frog cases reported where 

 both gonads were entirely missing and yet the Miillerian 

 ducts were well developed in such individuals. 



Because of these facts it is fair to conclude that the 

 appeal to the somatic sex characters completely fails as 

 proof of the transformation of female frogs into males. 



In closing, it should be pointed out that Witschi has 

 made but one original investigation of sex in anurans 

 (Witschi '14, no. 1). His later papers on the subject con- 

 tain no new observations or experiments but are purely 

 speculative endeavors to interpret his early work in ac- 

 cordance with Mendelism ('14, no. 2), later ('20, no. 3) 

 in accordance with internal secretions. 



