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the: story OR the: oak tre:e 
Because, as Charles Darwin said—and he was the 
greatest nature student of them all—, 
“Nature hates self-fertilization.” 
Has your father a garden ? Then he can tell you how 
cross-fertilizing with fresh stock makes his flowers 
stronger and prettier. Perhaps he has given you a 
flower bed all your own, to dig and cultivate for yourself. 
Suppose you plant in your bed two red rose bushes, side 
by side. Then suppose you arrange things so that the 
flowers of one of these bushes receive no pollen but their 
own, whereas the roses on the other bush receive pollen 
from a third bush. The first June, both bushes will bear 
like flowers, perhaps they will flourish equally well for 
several generations (a generation for a rose bush means 
a year), but in the end the self-fertilized bush will be¬ 
come sickly and weak and will be crowded to death by 
the fresh strength of the cross-fertilized bush. 
Because Nature knows the dangers of self-fertilization, 
she takes measures to prevent it. In a flower contain¬ 
ing both pistil and stamens she does not allow pistil 
and stamens to ripen at the same time, she sees to it that 
the pollen ripens and is carried away before the pistil 
is ready to receive it. The latter, then, must wait for 
the pollen from some other flower. Or, when pistil and 
stamens are bound to ripen at the same time, Nature 
twists the stamens out of reach of the pistil. In both 
