DAME NATURE AND HER CHILDREN 
every organism to its environment, — who can 
tell? 
The plants are all wise in their own way; they 
have to be, or cease to exist. The cultivated ones 
cannot shift for themselves like the weeds and wild 
growths; they have been too long dependent upon 
the care and culture of man for that; thrown upon 
their own resources, they perish, or else revert to 
the habits of their wild ancestors, as the animals 
do. 
I suppose it is impossible for us to conceive of the 
discipline, the struggle, the schooling, the selection, 
that all species of animals and plants have gone 
through in the course of biologic time, and that has 
given them the hardiness, the hold upon life, that 
they now possess. The strongest, the cleverest, the 
fittest have always had the best chance to survive. 
Natural competition has constantly weeded out the 
feeble, and still does so; but it does not do it so thor- 
oughly among men as among mice, because mice 
have no medicine, no surgery, no hospitals, no 
altruism. 
Different species of animals and plants differ 
greatly in their power to get on in the world. The 
ruffed grouse, for example, has a much deeper hold 
upon life than his cousin the quail, mainly because 
he is a more miscellaneous feeder. In deep snows 
the quail is in danger of perishing for want of food, 
but the grouse takes to the tree-tops and subsists 
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