xii LIST OF ILLUSTRATIONS 



FIG. PAGE 



47. Diagrams to show the number and size of the 



classes of individuals to be expected from 

 a cross involving Mendelian segregation 

 without dominance 135 



48. Photographs to show variation in ear length 



of two varieties of maize, of their F x off- 

 spring, and of their F 2 offspring . .Facing 138 



49. Diagram of sex-determination in partheno- 



genesis 162 



50. Diagram of sex determination when the female 



is homozygous, the male heterozygous . . 167 



51. Diagram of sex-determination when the female 



is heterozygous, the male homozygous . . 170 



52. Diagram of sex-limited inheritance when the 



female is a heterozygote 173 



53. Diagram of sex-limited inheritance when the 



female is a homozygote, as in the red-eyed 

 Drosophila 175 



