280 



THE THEORY OF THE GENE 



larly for the pollen. Self-fertilization should then give 

 1 XX+2 XY+1 YY. If YY dies there should be one fe- 

 male to two male offspring. This, however, was not the 

 result obtained. In order that the selfed male plants 

 should produce only males it must be assumed that the 

 X eggs die as gametes and the Y eggs only are func- 

 tional. As yet there is no evidence either for or against 

 this hypothesis. Until there is evidence bearing on this 

 question the case must be left open. 



