No. 632] SECONDARY SEXUAL CHARACTERS 



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scribed and reports that they all belong to the species 

 Uca pugnax, and show no signs of being hybrids. 



The most interesting cases of intersexes are those pro- 

 duced by Groldschmidt in crosses between different races 

 of the gypsy moth. He describes some crosses that give 

 individuals showing only a slight tendency towards the 

 opposite sex; other crosses go further until finally the 

 male may be completely transformed into females, the 

 change even including the appearance of eggs in the 

 gonads. Conversely females may be changed towards 

 maleness in various degrees depending on which varie- 

 ties are crossed. His interpretation in general is that 

 the two kinds of sex genes have different values in dif- 

 ferent races, so that the hybrids are in these respects be- 

 twixt and between so far as the influence of the sex genes 

 is concerned. As I have recently discussed at some length 

 Goldschmidt's view (see Carnegie publication, No. 278, 

 1919, and No. 285, 1919), I need not go over the ground 

 again. 



Harrison has more recently described intersexes in 

 the offspring of different species of moths belonging to 

 the family of Bistonidir. 



In this connection it is interesting to note that some of 

 the phenomena seen in these moth crosses appear when 

 crosses are made between two species of Drosophila, 

 namely, D. melanogaster and D. simulans. Made one way 

 the cross gives only females as A. M. Brown discovered, 

 and as Sturtevant has verified. Eeciprocally only males 

 are produced, as I have found, with a few females hash- 

 ing late in the series. In both cases, however, the h> l.rid 

 males and females from the two crosses, although sterile, 

 are strictly one or the other sex both in their gonads and 

 in their secondary sexual characters, but as stated 

 the gonads are rudimentary. Sturtevant 's recent dis- 

 covery of real intersexes in a race of Drosophila s,»,u- 

 lans has an important bearing on the interprets imi ot 

 intersexes. He finds in a certain line that individuals 

 appear that show characters both of the male and of the 



