28 Plant-Breeding 



the mother country; but in the course of a few genera- 

 tions it is found that the varieties in cultivation are unlike 

 the ones originally introduced, and from which they came. 

 As wild plants have become separated from each other as 

 species in the different geographical regions, so the cul- 

 tivated plants soon begin to follow similar lines of diver- 

 gence. In the beginning of the colonization of this 

 country, for example, all the varieties of apples were of 

 European origin. But in 1817, over sixty per cent of the 

 apples recommended for cultivation here were of American 

 origin, that is American-grown seedlings from the original 

 stock. At present, probably fully ninety per cent of the 

 popular apples of the Atlantic States are American pro- 

 ductions. The northern states of the Mississippi Valley 

 to which most of our eastern apples are not adapted, are 

 now witnessing a similar transformation in the adaptation 

 and modification of the varieties introduced from the East 

 and from Russia. The recently introduced Japanese 

 plums are conceded to be great acquisitions to our fruit- 

 growing, but no doubt the best results are yet to come 

 with the origination of domestic varieties of them. So 

 there is an irresistible tendency towards a divergence of 

 forms in different continental or geographical regions, 

 and much of the inevitable result is no doubt chargeable 

 to climatic environment. 



Change of seed. We may now pause for a moment to 

 consider two agencies or phenomena often associated with 

 the genesis of varieties. One of these is the fact that 

 the simple change of seed from one locality to another 

 usually gives a larger or better product or even more 

 marked variation. Mere transfer of seed is not of itself, 



