2T0 HEREDITY AND ENVIRONMENT 



ters of the other sex are present during de- 

 velopment, and traces of these may persist in 

 the adult; but one set of these characters de- 

 velops in the male and another in the female, so 

 that they may be called sex-limited. The de- 

 velopment of the secondary sex characters is 

 usually determined by the ovaries or testes, 

 which are the primary sex characters, though 

 in some instances they may develop in animals 

 which have lost their ovaries or testes, but in 

 the last analysis both primary and secondary 

 sex characters are dependent upon the sex- 

 determiner. Sex and sex-limited inheritance 

 are only special cases of Mendelian inheritance 

 in which conditions of dominance differ in the 

 two sexes, depending upon whether the factor 

 for sex is duplex or simplex. 



Sex-Linked Inheritance 



In this connection we may consider another 

 class of characters, which are linked with sex 

 but are in no wise connected with sexual repro- 

 duction. Such characters are not necessarily 

 limited to one sex or the other, as are many 

 primary and secondary sexual characters, but 



