THE HORMONE THEORY 



161 



might be made is that the female cliaracters are 

 present in tlic Y, in tliis case female producing 

 cln'omosome, or, if the female characters are merely 

 negative, that the male characters are in the X 

 chromosome, but only show themselves in the 

 homozygous condition, thus : — 



FEM/^LE 



MALE 



MALE FEMALE 



The male characters in the male, XX, would 

 appear because present in two chromosomes, but 

 would be recessive in the female because present 

 only in one chromosome. The validity of this 

 scheme, however, is disproved by the fact that males 

 can transmit the female characters of their race, as 

 in the case mentioned by Don caster where a male 

 Nyssia zonaria when crossed transmits the wingless 

 character of its own female. 



Another, perhaps better, suggestion is that the 

 somatic characters of both sexes are present in each. 

 Then as each somatic cell is descended without 

 segregation from the fertilised ovum, we may sup- 

 pose that the presence of the sex-chromosomes in 

 the somatic cells themselves in some way determines 

 whether male or female cliaracters shall develop, 

 without the aid of any hormones from the gonads. 



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