MALENESS AND FEMALENESS 497 



The third form of the Mendelian interpretation is supported by 

 a number of very striking facts, especially in regard to the 

 common currant-moth (Abraxas grossulariata) and the canary. 

 Let us re-state it very briefly. Assuming that there are sex- 

 determinants or ' factors ' of maleness and femaleness, the experi- 

 menters suggest (i) that these behave as Mendelian units, female- 

 ness being always dominant over maleness ; (2) that female 

 individuals are heterozygous as regards sex (having maleness 

 recessive) and that they give rise to equal contingents of male- 

 producing and female-producing ova ; (3) that male individuals 

 are homozygous as regards sex, being without the femaleness 

 factor, and give rise only to male-producing spermatozoa ; (4) 

 when a male-producing spermatozoon fertilises a male-producing 

 ovum the result is of course a male, when a male-producing sper- 

 matozoon fertilises a female-producing ovum the result is a 

 female, femaleness being by hypothesis dominant over maleness. 



The study of sex-limited inheritance in the currant-moth, 

 in the barred Plymouth Rock (and according to some in the 

 canary), suggests the conclusion that the female is the heterozygous 

 sex. But Morgan's study of the inheritance of red eyes and 

 short wings in the pomace-fly (Drosophila ampelophila) suggests 

 that the male is the heterozygous sex. It may be, then, that 

 in some organisms it is the one way, and in some the other, as 

 regards maleness and f jmaleness themselves. 



Doncaster refers to the confirmation which the Mendelian 

 theory of sex receives from the results of castration. In Verte- 

 brates the castration of the male may prevent the expression of 

 masculine features, but it does not induce the expression of 

 feminine characters. This may mean that the male is homozy- 

 gous that is, purely masculine, without any feminine characters 

 latent. We would, however, point out that in many cases there 

 is a lack of positiveness in the feminine characters ; it is mascu- 

 line characters which are positive and distinctive. In other 

 words, there might be a good deal of latent feminity in the 



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