HEREDITY 



tion has been undoubtedly the efficient cause of 

 change in both cases, but how and why applied 

 and to what sort of material is as uncertain 

 in one case as in the other. The few great 

 men who have succeeded in producing by their 

 individual efforts a new and more useful type 

 of animal or plant have worked largely by 

 empirical methods. They have produced a 

 desired result but by methods which neither 

 they nor any one else fully understood or 

 could adequately explain. So there exists as 

 yet no true science of breeding but only a 

 highly developed art which was practiced as 

 successfully by the ancient Egyptians, the 

 Saracens, and the Romans as by us. The 

 present, however, is an age of science; we 

 are not satisfied with rule-of-thumb methods, 

 we want to know the why as well as the how 

 of our practical operations. Only such knowl- 

 edge of the reasons for methods empirically 

 successful can enable us to drop out of our 

 practice all superfluous steps and roundabout 

 methods and to proceed straight to the mark 

 in the most direct way. The industrial his- 

 tory of the last century is full of instances in 



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