ON SOMATIC SEX-CHARACTERS 89 



female heterozygous in Vertebrates : that is to say, 

 the female sex-character and the female secondary 

 sex-characters are entirely wanting in the male. 

 This argument assumes that the secondary characters 

 are essentially of sexual nature without inquiring 

 how they came to be connected with sex, and it 

 ignores the fact that the influence of castration on 

 such characters is a phenomenon entirely beyond the 

 scope of Mendelian principles altogether. The fact 

 that castration does affect, in many cases very pro- 

 foundly, somatic characters confined to one sex, 

 proves that Mendelian conceptions, however true up 

 to a certain point, are by no means the whole truth 

 about heredity and development. For it is the 

 essence of Mendelism as of Weismannism that not 

 only sex but all other congenital characters are 

 determined in the fertilised ovum or zygote. The 

 meaning of a recessive character in Mendelian 

 terminology is one that is hidden by a dominant 

 character, and both of them are due to factors in 

 the gametes, particularly in the chromosomes of the 

 gametes which come together in fertilisation. For 

 example, in fowls rose comb is dominant over single. 

 A dominant is something present which is absent 

 in the recessive : the rose comb is due to a factor 

 which is absent from the single. The two segregate 

 in the gametes of the hybrid or heterozygote, and if 

 a recessive gamete is fertilised by another recessive 

 gamete the single comb reappears. But castration 

 shows that the antlers of stags and other such 

 characters are not determined in the zygote when 

 the sex is determined, but owe their development, 

 partly at least, to the influence of another part of 

 the body, namely, the testes during the subsequent 



