THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



maturation was proposed by P. W. Whiting (1933e) 

 to explain the absence of diploid males in out- 

 crosses. In these crosses, the egg, being in 

 an indecisive stage of reduction division at 

 the time of fertilization, V70uld eliminate into 

 the polar body the same sex factor that was be- 

 ing carried in by the sperm, and thus the fer- 

 tilized egg would always be heterozygous for 

 the sex factor, that is, female-producing. In 

 close-crosses, however, some influence seemed 

 to prevent this mechanism of differential matu- 

 ration from affecting the disposal of the like 

 sex factor; and so there were some diploids 

 which, being homozygous for the sex factor, 

 were males. 



It had been noted previously (A. R. Whiting, 

 1925) that females mated to related males were 

 less fecund than those mated to unrelated males . 

 This appeared to be the result of excess bad 

 eggs in close-cross fraternities. On the basis 

 of the theory of complementary factors, these 

 eggs are considered to be male-producing zy- 

 gotes, and increased fecundity in out-crosses 

 the result of a replacement of these by female- 

 producing zygotes. 



This hypothesis of complementary factors was 

 suggested after study of complementary effects 

 in eye-color and in genitalia of haploid mosaic 

 males, which occur occasionally among the prog- 

 eny of unmated females heterozygous for mutant 

 traits (P. W. Whiting, Greb, and Speicher , 1934) . 

 Interpretation of gynandroidism as a complemen- 

 tary effect led to the conclusion that females 

 are heterozygous and that normal males are X 

 and Y with equal frequency. This hypothesis of 

 complementary factors was proved true by sex- 



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