498 HEREDITY AND SEX 



castrated male without there being much to show for it. It 

 would be extremely interesting to experiment with some case 

 like the Red-necked Phalarope, where the female bird is the more 

 masculine of the two. 



When a Vertebrate female is castrated, or when the ovary 

 atrophies, there is often a development of masculine characters. 

 We must refer again to the case of the pullet. Guthrie has 

 shown that a castrated female chicken may acquire not only 

 the outward structural features of the opposite sex cock's 

 comb, wattles, long hackle and tail feathers, spurs, etc. but 

 the behaviour as well. 



In Crustaceans the course of events is curiously the reverse of 

 what is true of Vertebrates. A female whose ovary has been 

 destroyed by a Rhizocephalous parasite has its secondary sex 

 characters reduced, but a castrated male assumes more or less 

 completely the characters of the female. It may be that in this 

 case the female characters are more positive, e.g. the broad 

 abdomen. " If the parasite dies and the host recovers, the ovary 

 of the female may again become functional ; but in the male under 

 such circumstances eggs may be produced in the testis. Geoffrey 

 Smith concludes from these observations and from others on 

 the Cirripedes, that the female is homozygous in sex and the 

 male heterozygous. There seems no a priori reason," Mr. 

 Doncaster continues, " why this should not be true in the case 

 of Crustacea and flowering plants, while the converse is the case 

 in moths and vertebrates." 



The fact that the proportions of the sexes are sometimes 

 very variable, as Heape points out in regard to canaries, does not 

 of itself tell against the view that the ova are determined at an 

 early stage to be male-producers or female-producers. There 

 may be a process of discriminate selection during the maturing 

 of the ova, and we know that in higher Vertebrates the possible 

 ova do not all come to maturity. 



That the proportions of the sexes in different types are very 



