CHAPTER VII 



MENDELISM 



WE must now proceed to consider some more com- 

 plicated cases of Mendelian inheritance. But before 

 doing so it will be advisable to study the inheritance 

 of two pairs of characters simultaneously. 



Suppose that we cross two breeds of cattle differing 

 in two distinct particulars say, the one is black and 



FIG. 8. 



hornless, the other red and horned. Black colour is 

 dominant to red, and the hornless condition dominant to 

 the horned. The first generation will therefore be black 

 and hornless. How will the characters be distributed 

 amongst the individuals of the following generation ? 



If we take a square, and divide it into four equal 

 parts, as in Fig. 8, we may shade three of the quarters 

 to represent the fact that three-fourths of the second 

 generation will be black, and one-fourth red. 



The other pair of characters is inherited indepen- 

 dently. We must then divide each quarter again into 



