110 SEX 



the nature of a ferment which is either 

 present or absent in every germ-cell. This 

 is not at all incompatible with a physio- 

 logical interpretation, for it may be that this 

 mysterious sex-determinant acts as an acceler- 

 ant or depressor of the rate of metabolism ; and 

 it may be that the nutritive conditions within 

 the reproductive organs during the processes 

 of oogenesis and spermatogenesis exercise a dis- 

 criminate selection allowing more of the male- 

 producers or more of the female-producers to 

 survive. 



The Mendelian interpretation accounts well 

 for the usual equality between males and 

 females in a given stock, less well for the 

 strange disproportions which occur within a 

 single family. The latter may, however, be 

 due to a discriminate selection during the 

 production and maturing of the ova. 



Doncaster refers to the confirmation which 

 the Mendelian theory of sex receives from the 

 results of castration. In vertebrates, the 

 castration of the male may prevent the ex- 

 pression of masculine features, but it does 

 not induce the expression of feminine char- 

 acters. This would suggest that the male is 

 homozygous, that is to say, purely masculine, 

 without any feminine characters latent. The 

 castrated female, on the other hand, often 

 develops a striking series of masculine features, 

 which suggests that she is heterozygous, i. e. 

 with masculine characters latent. We would 

 point out, however, that in many cases there 

 is a lack of positiveness in the feminine char- 

 acters as compared with the masculine ones. 

 So that there might be considerable femininity 



