44 The Third and Fottrth Generation 



white is evidently dominant. Whether a given 

 character will behave as dominant or not 

 can only be told by trying it out by actual 

 breeding. 



Dominance may often be only partial, 

 possibly it is never absolutely complete. The 

 crossing of white and black Andalusian fowls 

 is a case in point. The children, instead of 

 being either black or white are black diluted 

 with white, called by the chicken fancier a 

 "blue." Of the grandchildren one-fourth are 

 pure black, one-fourth pure white, and one-half 

 ' ' blue ' ' hybrids. Similarly, when red and white 

 four-o'clocks are crossed the children are all 

 pink blossomed; neither red nor white is com- 

 pletely dominant. The grandchildren are one- 

 fourth pure red, one-fourth pure white, and 

 one-half pink. 



QUESTIONS 



1. What do you mean by heredity ? 



2. How did Mendel go about it in his work with ■ 

 peas to make sure of crossing two varieties so as to get 

 a hybrid ? 



