SHULL INHERITANCE OF SEX IN LYCHNIS 



121 



maintain that this is so, provided sex is inherited as a Mendelian 

 character. But if sex inheritance be not primarily Mendelian, but 

 only associated with and perhaps determined by Mendelian charac- 



. , , , 



FIG. 2. Variation in percentages of females and in percentages of pur pie-no wered 

 plants in 94 families of Lychnis dioica produced by crossing heterozygous purple 

 with white; broken curve represents females; both curves if monomodal belong to 

 PEARSON'S Type I. See constants in table IV. 



ters in a few cases, the determination of a sex ratio might not be a 

 process distinct from the inheritance of sex itself. 



The assumption that the sexes differ from each other by a single 

 unit character, and that one sex is heterozygous and the other homo- 



