ONTOGENESIS 247 



hybrid and the female as a pure or homozygous 

 organism. The male character he regarded as 

 dominant. All ova were unisexual, and hence 

 always female, whether fertilized or not. The 

 spermatozoa, on the other hand, carried either 

 male or female characters. 



If the female ovum was fertilized by a sperma- 

 tozoon carrying only female characters, it, of 

 course, remained female; but if it were fertilized 

 by a spermatozoon carrying male characters, the 

 male character always being dominant, it, of 

 necessity, became a male. 



The theory is shown to be false by remember- 

 ing that the unfertilized eggs of bees develop into 

 males. 



The reverse aspect of the case might overcome 

 this objection as Bateson has suggested. Thus, 

 it might be the female that is the hybrid with 

 femaleness dominant. Though by this assump- 

 tion we are relieved of the dilemma into which we 

 were thrown by the peculiarity of the bee's eggs, 

 we fall into a new one, because of the observa- 

 tions by Henking, McClung, and Wilson that 

 morphologically different spermatozoa determine 

 the sex of many kinds of insects, and because 

 of the difficulty of explaining many of the cir- 

 cumstances attending parthenogenesis. 



A very ingenious solution of the difficulty of 

 avoiding entanglements in endeavoring to ex- 

 plain sex along Mendelian lines has been thought 

 out by L. Doncaster, who suggests that the 

 Mendelian pairs are not male and female, but are 

 male and no sex and female and no sex. The 

 male is pure, but produces spermatozoa of two 

 kinds, viz., those with sex determinants and those 

 without them. The female is a sex hybrid pro- 

 ducing both male and female eggs in equal num- 

 bers. He assumes that there is selective fertiliza- 

 tion by which female eggs fertilized by male 



