Selection and Mutation. 15 



which enabled him to build his theory of descent on foun- 

 dations supplied by breeders. At the same time he left 

 many points untouched, or at any rate undecided, and 

 for the final settlement of such questions I fear that the 

 statements of breeders will seldom suffice. 



It is somewhat remarkable that purely scientific in- 

 vestigation has not kept pace with practical experience. 

 This wide field is still open to cultivation, and will, with- 

 out doubt, some day bear a rich harvest. 



It is my object in this section to test the statements 

 of practical breeders, so far as they admit of such criti- 

 cism. I pay the sincerest tribute to their high practical 

 value especially as in this case science is far behind them. 

 But their application to the theory of descent is another 

 matter. Real service to science can only be rendered 

 by confining oneself to thoroughly authenticated cases. 



In conclusion : The analogy between the origin of new 

 forms in nature and in a state of cultivation forms one 

 of the chief supports of the theory of descent. But the 

 fact of their origin does not help us to choose between 

 the theory of selection and the theory of mutation ; noth- 

 ing short of a knowledge of the nature and mode of their 

 origin will help us to decide. But on this all-important 

 point the experience of breeders teaches us very little. 



I shall try to relate what they tell us in the third chap- 

 ter of this Part. 



