LYMANTRIA DISPAR 35 



European? x Japanese o=F.i: all sons normal, all daughters 



intersexual 

 F.2: all sons normal, half daughters 

 normal, half intersexual (the 

 grade of intersexuality being as 

 that in the mother. Only the 

 lower-grade intersexuals could 

 be bred from) 



Japanese ? x European o =F.i: sons and daughters all normal 



F.2: all daughters normal, half sons 

 normal, half intersexual 



For purposes of description and discussion Goldschmidt 

 refers to the Japanese race in these experiments as a 'strong' 

 race, and the European as 'weak'. Female intersexuality is 

 produced in an F.i when a 'weak' female is crossed with 

 a 'strong' male. Male intersexuality is exhibited by a pro- 

 portion of males in the F.2 of the cross 'strong' female x 

 *weak' male. From these results it is seen that sex-determina- 

 tion is a phenomenon partaking of the nature of a genie 

 balance, sex being dependent upon a particular relation of 

 certain determiners, their relative 'strength' or 'weakness'; 

 in other words, a balance or lack of balance of these deter- 

 miners. It is clear that these determiners are of two kinds, 

 one of which shifts sex toward the female type, the other 

 toward the male. 



In order to determine how these sex-determining factors 

 were transmitted, Goldschmidt carried out the following 

 breeding experiments: 



A. F.I weak 2 x strong o gave cj'cJ all normal and ?? intersexual 

 F.2 weak $ x strong o gavecJcJ all normal; ?? half normal, half 



intersexual 

 Backcross. Weak $ x F.i (weak ? x strong <^) o gave ob* 



normal; 2$ half normal, half intersexual 

 Backcross. Weak $ x F.i (strong $ x weak (J) o gave 36 



normal; ?? half normal, half intersexual 

 Backcross. F.i (weak ? x strong o) ? x weak ^ gave cJcJ all 



normal; $2 all normal 

 Backcross. F.i (weak ? x strong o) ? x strong o gave S6 all 



normal; ?$ all intersexual 



In all these crosses it is the maternal line that is 'w^eak'. The 

 results show at once that the 'strength' which produces 



