246 BIOLOGY: GENERAL AND MEDICAL 



minant, or at least is the sex index. The differ- 

 ence between the male and female organism is 

 that the male comes from an egg which develop- 

 ing either parthenogenetically or after fertiliza- 

 tion contains only a single z-element, while the 

 female starts from one which developing either 

 parthenogenetically or after fertilization contains 

 two ^-elements. 



The ovum of a sexual egg in the process of 

 maturation discards half of its normal comple- 

 ment of the ^-element. If it be subsequently 

 fertilized by a spermatozoon containing an x- 

 element, these elements being paired, the result- 

 ing organism is a female; if by a spermatozoon 

 devoid of an ^-element, the elements being un- 

 paired, into a male. 



H. That the sex of the offspring is a Mendelian 

 character but still an accident of fertilization. 

 To fully comprehend this theory it is necessary 

 that the reader shall read the theory of Mendel 

 as outlined in the chapter upon "Conformity to 

 Type." 



Castle, Correns, Bateson, Doncaster, and others 

 have written in support of this view, and their 

 theories are ingenious and suggestive. 



Castle believes that both male and female 

 organisms are Mendelian hybrids (male-female 

 hybrids), maleness and femaleness being Mendel- 

 ian characters, with respective male and female 

 dominance. During the maturation of the 

 germinal cells the usual disruption of character 

 takes place, so that male and female ova and 

 male and female spermatozoa are produced. He 

 made the assumption that there were selections 

 and repulsions in fertilization so that spermatozoa 

 and ova bearing the same sex never conjoined. 



Instead of regarding both male and female as 

 such, Correns looked upon the male as the sex 



