I have endeavoured
to show are unsound. Even in rejecting that phase of sexual selection
depending on female choice, I insist on the greater efficacy of natural
selection. This is pre-eminently the Darwinian doctrine, and I therefore
claim for my book the position of being the advocate of pure Darwinism.

I wish to express my obligation to Mr. Francis Darwin for lending me
some of his father's unused notes, and to many other friends for facts
or information, which have, I believe, been acknowledged either in the
text or footnotes. Mr. James Sime has kindly read over the proofs and
given me many useful suggestions; and I have to thank Professor Meldola,
Mr. Hemsley, and Mr. E.B. Poulton for valuable notes or corrections in
the later chapters in which their special subjects are touched upon.

GODALMING, _March 1889_.

CONTENTS

CHAPTER I

WHAT ARE "SPECIES" AND WHAT IS MEANT BY THEIR "ORIGIN"

Definition of species--Special creation--The early
transmutationists--Scientific opinion before Darwin--The problem
before Darwin--The change of opinion effected by Darwin--The
Darwinian theory--Proposed mode of treatment of the subject

CHAPTER II

THE STRUGGLE FOR EXISTENCE

Its importance--The struggle among plants--Among
animals--Illustrative cases--Succession of trees in forests of
Denmark--The struggle for existence on the Pampas--Increase of
organisms in a geometrical ratio--Examples of rapid increase of
animals--Rapid increase and wide spread of plants--Great
fertility not essential to rapid increase--Struggle between
closely allied species most severe--The ethical aspect of the
struggle for existence

CHAPTER III

THE VARIABILITY OF SPECIES IN A STATE OF NATURE

Importance of variability--Popular ideas regarding
it--Variability of the lower animals--The variability of
insects--Variation among lizards--Variation among
birds--Diagrams of bird-variation--Number of varying
individuals--Variation in the mammalia--Variation in internal
organs--Variations in the skull--Variations in the habits of
animals--The variability of plants--Species which vary
little--Concluding remarks

CHAPTER IV

VARIATION OF DOMESTICATED ANIMALS AND CULTIVATED PLANTS

The facts of variation and artificial selection--Proofs of the
generality of variation--Variations of apples and
melons--Variations of flowers--Variations