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To the solid ground
Of Nature trusts the mind that builds for aye;
Convinced that there, there only, she can lay
Secure foundations."

WORDSWORTH.

LONDON:
SWAN SONNENSCHEIN & Co., PATERNOSTER SQUARE, E.C.

1895.

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PREFACE.

IT

T may be well at the outset clearly to define the posi

tion taken in the following work. The author believes that the process of Organic Evolution has taken place, but he does not believe that Natural Selection has been the means by which that result has been brought about. If any reader is of opinion that Organic Evolution and Natural Selection are synonymous terms, he is recommended at the outset to turn to the first chapter of the Third Book, in which it is attempted to show that Natural Selection is not identical with Organic Evolution.

In the second place, the reader is warned against the idea that any selection in nature can properly be called Natural Selection. Natural Selection is a very complex term, It is based on the analogy supposed to exist between the process of artificial selection and a process which is supposed to take place in nature.

. In Natural Selection the struggle for existence is supposed to be the selecting power, and it works by life and death ; it secures the survival of the fittest, and hence it is based upon the principle of utility. It selects from those variations which are necessarily associated with sexual reproduction. It asks only for small variations, and it undertakes that the slight favourable variations shall survive. In this way it now produces the transmutation of species, and in a far-off past it was the only or

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