CHAPTER XIV 



ECONOMICAL 



Since heredity lies at the basis of the breeder's work, 

 it is evident that any contribution to a more exact know- 

 ledge of this subject must prove of service to him, and 

 there is no doubt that he will be able to profit by Men- 

 delian knowledge in the conduct of his operations. In- 

 deed, as we shall see later, these ideas have already led 

 to striking results in the raising of new and more profitable 

 varieties. In the first place, heredity is a question of in- 

 dividuals. Identity of appearance is no sure guide to 

 reproductive quaUties. Two individuals similarly, bred 

 and indistinguishable in outward form may nevertheless 

 behave entirely differently when bred from. Take, for 

 instance, the family of sweet peas shown on Plate IV. 

 The F2 generation here consists of seven distinct types, 

 three sorts of purples, three sorts of reds, and whites. 

 Let us suppose that our object is to obtain a true breeding 

 strain of the pale purple picotee form. Now from the 

 proportions in which they come we know that the dilute 

 colour is due to the absence of the factor which intensifies 

 the colour. Consequently the picotee cannot throw the 



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