LUTHER BURBANK 
trees have been cut off, there will spring up what 
at first appears to be a growth of oaks alone. But 
in fifteen or twenty years the growth of Douglas 
Spruce will entirely overshadow the oaks, ulti- 
mately kiling them off altogether, and presenting 
yet another illustration of the practical operation 
of natural selection. 
But there is very great variation among the 
different species of conifers as to rapidity of 
growth. So there is fine opportunity for the experi- 
menter to select the more rapid-growing trees, and 
thus to develop a race of timber trees of excep- 
tional value. 
The experiment is not difficult because the 
Douglas Spruce bears seed while quite young, par- 
ticularly when the trees stand by themselves. The 
seed remains in the cones for some time, to mature, 
so that it may be collected at any season of the 
year. The seeds germinate readily, the seedlings 
may be easily transplanted, and in general this is 
one of the easiest conifers with which to work. 
The hardiness of the tree and its adaptation to all 
soils and climates are further merits that com- 
mend it to the attention of the plant developer, 
whether he have in mind a tree for ornament or 
for reforestration. 
The experimenter should know, however, that 
the seed of the spruce, unlike that of the redwood 
[290] 
