LUMBER TREES 123 



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what each tree is now exteriorly gives us but 

 faint suggestion of what it might be were its 

 unrealized hereditary possibilities to be made 

 actualities. 



So far as we know at present, the only way in 

 which these unrealized possibilities may in any 

 conspicuous measure be brought out is by 

 hybridizing species that have so far diverged 

 that they lie almost at the limits of affinity. By 

 such union of hereditary tendencies that have 

 long been disunited, racial traits that are reminis- 

 cent of the old days when the Northern Hemi- 

 sphere enjoyed a tropical climate may be revived, 

 and a tendency to repeat a gigantic growth that 

 characterizes ancestors vastly remote will be 

 revealed. 



Such is the explanation of the strange and 

 otherwise inexplicable phenomena of gigantism 

 manifested by my hybrid walnuts. And such is 

 our warrant for believing that all other species 

 of native trees have possibilities of develop- 

 ment that are unrevealed in the exterior appear- 

 ance of their present-day representatives and 

 that can be revealed, so far as we know, only by 

 hybridization. 



