THE CREATION OF NEW TREES 
apparently been impossible. But this much 
may be done even in these remote cases: 
“Two given species will not readily yield 
to union. Make a cross between them, take 
the seeds of the progeny and plant them. 
Cross two other diverse species in the same 
way and plant the seeds of their progeny. 
Then to the progeny of the first union unite 
the progeny of the second, and from this later 
union you may sometimes get marvelously 
satisfactory results. The outcome of either 
main cross would be unsatisfactory, perhaps 
unimportant; the union of their progeny may 
obviate the difficulty. The possibilities of 
such crossing and its subsequent selection are 
inconceivably great. 
“It is my opinion that one of the most 
important, in some ways the most important 
of all the many fields open now to the plant- 
breeder, is this one of the production of new 
and the improving of old trees. I believe it 
to be of immense significance commercially.” 
Closely allied to this production of a tree is 
the improvement of the product of the tree, 
its nuts. Deciding that it would be well to 
have an English walnut with a thinner shell, 
65 
