122 BREEDING 



can be easily described in terms of Mendelian here- 

 ditary processes. 



The reader should be familiar by now with the 

 manner of inheritance of Mendelian pairs of characters 

 in the result of crossings in which only one such 

 pair is involved, and in crossings in which two such 

 pairs are involved ; and with those cases in which 

 the members of one pair of characters exert no effect 

 on members of another pair, i.e. in which cases there 

 is a 9 : 3 : 3 : 1 ratio in the second hybrid generation ; 

 and also with those cases in which a member of one 

 pair of characters depends for its manifestation on 

 the presence of a member of another pair, in 

 which cases there is a 9:3:4 ratio in the second 

 hybrid generation. 



Our review of the main phenomena of Mendelian 

 inheritance is now concluded. Most of the illustrative 

 cases are such as can be bred by the reader if he has 

 the curiosity to do so. A full description of the 

 conduct of a breeding experiment, together with 

 the names of the varieties which exhibit the characters 

 referred to, will be found in Chapter X. 



We now pass on to the subject alluded to at the 

 end of the last chapter, namely, the nature of the 

 Mendelian pair of characters. This question is of 

 the greatest interest to the practical breeder and to 

 the investigator. But we are as yet very far from a 

 satisfactory answer to it. The work of the practical 

 breeder would be greatly simplified by the possession 

 of some simple rule which would tell him before he 



