LUTHER BURBANK 



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 

 as to the various results of hybridizing species 

 more or less closely related that have been detailed 

 in the preceding chapters. 



To some readers the entire illustration of the 

 elfin architects may seem whimsical. But it is 

 presented in all seriousness in the hope that it 

 may serve a useful purpose. Not that I would 



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