194 PHYSICAL BASIS OF HEEEDITY 



sexes'* that arise when the European and Japanese race 

 of gypsy moths, Lymantria dispar and L. japonica, are 

 crossed. Riddle has described doves obtained by crossing 

 the white ring dove (Streptopelia alba) and the Japanese 

 turtle dove (Turtur orientalis) that are intersexual in 

 their mating habits. Olga Kuttner and Banta have found 

 that certain lines of Cladocerans (Simocephalus) may 

 produce (parthenogenetically) ^ intersexual individuals * * 

 in the sense that an individual may possess some of 

 the secondary sexual differences of one sex and some 

 of the other. ^ 



Some of Goldschmidt's combinations between different 

 races of gypsy moth produce only intersexual females, i.e., 

 individuals that are mostly female, but have also, in spots, 

 male characters. In the most extreme cases they are 

 almost like males, not only in color, but even in the partial 

 production of testes. Other racial combinations give male 

 intersexes, i.e., individuals that are foij the most part 

 males, but show, in spots, some of the characteristics of 

 the female. Goldschmidt explains these results by the 

 assumption that the sex factors have different quantita- 

 tive values in the different races. He represents the 

 female by FFMm, and the male by FFMM. If the FF ' ' fac- 

 torial set'* is represented by 80 units, and the *' present*' 

 male factor, M, by 60 units, then the above formula for the 

 female becomes 80-60 = + 20, and the male formula 

 becomes 80- (60 + 60)= -40. In the former, female units 

 * dominate," in the latter, the male. Values like these 

 can be arbitrarily set for all the different races. For 

 instance, to the ^^weak" European race and the '^strong" 

 Japanese the following values are assigned : 



