LUTHER BURBANK 
He does not attempt to make squash vines into 
oak trees, or blackberry briers into tomatoes. 
He recombines those newer, and hence less im- 
portant, structures and qualities of which the fact 
of their Mendelizing is adequate proof of their 
newness and relative unimportance. If he would 
get beyond this and create really new forms, add- 
ing something to the plant that no ancestor of the 
plant ever had, he could hope to do this only if a 
term of life were granted him that would be meas- 
ured not in mere years but in millenniums. For 
evolution is a slow process, and the history of the 
development of natural species is measured in 
geological eras. 
SELECTION AND MENDELISM ; 
Perhaps it may be worth while to illustrate this 
matter a little more in detail, that we may make 
clear precisely what manner of thing the plant 
developer is doing when he produces a new race 
by selection. 
We have stated over and over that the process 
of hybridizing and the process of selection are 
complimentary. One supplements the other. In 
hybridizing we make possible new combinations of 
the hereditary factors, and in selecting through 
successive generations we isolate certain definite 
combinations, and thus produce what we call new 
varieties. Now it is frequently stated by the ex- 
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