IMPROVING SMALL FRUITS 67 



for himself a picture of the various activities of 

 the elfin architects in those cases where the diver- 

 sity between the different hereditary factors is 

 greater than that between the two kinds of black- 

 berries, but less than that between the apple and 

 the dewberry. 



We saw in such cases as that of the Primus 

 berry and the Sunberry that when the two germ 

 plasms were at just a certain stage of divergence 

 the resulting hybrid presented a compromise of 

 characteristics. We may suppose that the elfin 

 architects in the germ plasm are in such a case 

 to be compared with human architects, one of 

 whom, let us say, presents blocks of stone as the 

 chief building material while the other presents 

 bricks. Stone and bricks cannot be blended, but 

 they may be variously combined, for example, 

 placed in alternate layers, to make a structure 

 that is neither a stone house nor a brick house, 

 although it is a house built of both stone and 

 brick. 



In the same way the Primus berry is neither a 

 blackberry nor a raspberry, although its com- 

 ponent hereditary factors are all either black- 

 berry or raspberry factors. 



But we need not attempt to carry the illustra- 

 tion further. The reader who has followed it may 

 make his own application, in reviewing the facts 



