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THE AMERICAN NATURALIST [Vol. XL1V 



No less than four hypotheses have been already ad- 

 vanced to explain these facts. Doncaster assumed, at 

 first, that each sex produced male and female gametes; 

 that in the first hybrid generation the male gametes bear 

 the grossulariata character and the female the lacti- 

 color; that in the male no such coupling occurs. Bate- 

 son and Punnet simplified this hypothesis by assuming 

 that the female is heterozygous for sex, the male homo- 

 zygous; that femaleness is dominant to maleness; that 

 in the hybrids the character for femaleness and that for 

 grossulariata repel each other so that each germ cell 

 gets one or the other. The results are summed up in 

 Table I. 



TABLE I 



L9, G$ LL 9 <? - 



Castle pointed out that Wilson's sex-hypothesis, that 

 two X chromosomes stand for femaleness and one X for 

 maleness, will not explain the case of Abraxas, but that 

 by the Irypothesis of one X standing for femaleness and 

 no X for maleness, the results can be explained; pro- 

 vided Bateson's assumption of repulsion is also em- 

 ployed. Thus if in the Bateson-Punnett table (above) 

 the male signs are omitted, and X put in for the female 

 signs, the results just stated follow, as the next table 

 shows. It will be observed that Castle has simply omitted 

 the male and female signs and substituted X for female- 

 ness. When it is absent the male is assumed to develop. 



