LUTHER BURBANK 



beginning to assume proportions that make them 

 have value in the eyes of the lumberman. At 

 twenty years they are handsomely proportioned 

 trees of notable dimensions. 



The contrast between a Paradox or a Royal wal- 

 nut and a black walnut or a Persian walnut of 

 the same age, at any stage of growth, is startling. 



If we attempt to explain these anomalies of 

 growth, we must assume that the remote an- 

 cestors of the walnuts away back, let us say, in 

 the preglacial days were trees of gigantic size. 

 Their descendants of our day are a relatively de- 

 generate lot, made so by the modified climate to 

 which they have been obliged to adapt themselves. 

 But the mingling of germ-plasms of the different 

 species makes it possible, in some way that we as 

 yet do not very clearly understand, for the heredi- 

 tary factors of giganticism, long submerged, to 

 make their influence felt. 



A somewhat similar stimulus to vigor of growth 

 is a not unusual attribute of hybrids. We have 

 seen that many of the large fruits and flowers and 

 vegetables that Mr. Burbank has produced are 

 thus to be explained. But the case of the walnuts 

 is so extreme that these trees stand in a class by 

 themselves. It is doubly significant because these 

 are the first experiments in hybridizing forest 

 trees that produced notable results ; and because, 

 as I said, the ultimate economic importance of this 

 discovery can scarcely be overestimated. 



There is apparently no reason why the same 

 principle of hybridization should not be extended 



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