76 



HEREDITY AND SEX 



kinds some produced yellow and green seeds again 

 in the ratio of 3 : 1 ; others produced only yellow 

 peas. Now, if the yellows that bred true were counted, 

 it was found that the number was but one-third of 

 all the yellows. 



FIG. 42. Illustrating Mendel's cross of yellow (lighter color) and greeu 

 (dark color) peas. 



