SECONDARY SEXUAL CHARACTERS 205 



blending when crossed, as appears to have happened in the 

 case of other ancient characters. 



Before proceeding further with this question it is neces- 

 sary to clear up certain points connected with secondary 

 sexual characters. Secondary sexual characters are those 

 which, though appearing in all individuals of the same 

 sex and not in those of the other sex, are not connected 

 directly with the sexual function, that is, with reproduction. 

 Such characters are the beard and voice of a man and the 

 antlers of a stag. There is a great deal of evidence which 

 suggests that the potentiality of producing these characters 

 is present in the individuals of both sexes. Among mammals 

 and birds we constantly find that the characters of the young 

 mule arc those of the female, minus of course a few special 

 characters. The plumage of the young cock pheasant is 

 similar to that of the adult female ; a boy's voice is similar 

 to that of a woman. If during infancy the sexual glands 

 are removed from a male animal, the male secondary sexual 

 characters do not appear. Not only are the physical char- 

 acters, such as change in voice and plumage, inhibited, but 

 mental characters, such as pugnacity, do not develop. There 

 are some direct experiments which suggest very strongly 

 that the appearance of the secondary sexual characters is 

 dependent upon the presence in the body of the sexual 

 glands. It has been found that if the fresh sexual gland 

 of a cock be pounded up and injected hypodermically into 

 hens, their combs and wattles grow to a very large size. On 

 the cessation of the injections the combs diminish until they 

 have reached the normal size again. 1 It has also been shown 

 that in the cock, if even a very small portion of the sexual 

 gland is left in the body, the secondary sexual characters 

 become fully developed, and this in spite of the fact that 

 the bird is quite unable to fertilise the eggs of the hen. The 

 same has been shown in the case of sheep. 2 If, however, the 



1 Walker, C. E., " The Influence of the Testis upon the Secondary Sexual 

 Characters of Fowls," Proceedings of the Royal Society of Medicine, April 1908. 



- Shattock and Seli<5inann, Transactions of the Pathological Society of London, 

 vol. Ivi. p. 57, 1905 ; vol. Ivii. p. 69, 1906. 



