to study the variation of nests of the same species of birds. 
A pair of robins will build a nest loosely put together in an 
exposed situation, such a nest would be blown to pieces by 
the first high wind and the eggs broken or the young destroyed 
by some predatory cat and thus the offspring perish, while 
another pair with a solidly constructed nest carefully con¬ 
cealed, would survive these adverse conditions and the young 
would live to perpetuate by the law of inheritance the superior 
qualities of their parents. A good illustration of the doctrine 
of natural selection. 
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