HEEEDITY 



of a curious sort of heredity known as sex- 

 limited heredity. 



FIG. 51. Diagram of sex-determination when the female is 

 heterozygous, the male homozygous. 



Every one who knows anything about poultry 

 is acquainted with the popular American breed 

 known as the barred Plymouth Bock. In this 



170 



