CHAPTER XVI 



ECONOMICAL 



Since heredity lies at the basis of the breeder's 

 work, it is evident that any contribution to a more 

 exact knowledge of this subject must prove of service 

 to him, and there is no doubt that he will be able 

 to profit by Mendelian knowledge in the conduct of 

 his operations. Indeed, 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 individuals. 

 Identity of appearance is no sure guide to repro- 

 ductive qualities. Two individuals similarly bred 

 and indistinguishable in outward form may never- 

 theless behave entirely differently when bred from. 

 Take, for instance, the family of sweet - peas 

 shown on Plate IV. The F^ generation here con- 

 sists 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 pro- 

 portions in which they come we know that the 

 dilute colour is due to the absence of the factor 

 which intensifies the colour. Consequently the 



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