Chapter III

THE LAWS OF VARIABILITY WITH RESPECT TO ANIMALS AND PLANTS.

Inherited Effect of Changed Habits 48

Effects of the Use and Disuse of Parts 50

Vague Origin of our Domestic Animals 52

Descent of the Domestic Pigeon 53

Origin of the Dog 55

Origin of the Horse 57

Causes of Modifications in the Horse 58

“Making the Works of God a mere Mockery” 59

Variability of Cultivated Plants 61

Savage Wisdom in the Cultivation of Plants 62

Unknown Laws of Inheritance 64

Laws of Inheritance that are fairly well established 66

Inherited Peculiarities in Man 67

Inherited Diseases 68

Causes of Non-Inheritance 69

Steps by which Domestic Races have been produced 71

Unconscious Selection 73

Adaptation of Animals to the Fancies of Man 74

Doubtful Species 75

Species an Arbitrary Term 77

The True Plan of Creation 79

IV.

THE STRUGGLE FOR EXISTENCE.

Death inevitable in the Fight for Life 82

“Inexplicable on the Theory of Creation” 84

Obscure Checks to Increase 85

Climate as a Check to Increase 86

Influence of Insects in the Struggle for Existence 88

No such Thing as Change in the Result of the Struggle 90

V.

NATURAL SELECTION; OR, THE SURVIVAL OF THE FITTEST.

An Invented Hypothesis 93

How far the Theory may be extended 94

Is there any Limit to what Selection can effect? 96

Has Organization advanced? 97

A Higher Workmanship than Man’s 99

Why Habits and Structure are not in Agreement 102

No Modification in one Species designed for the Good of Another 103

Illustrations of the Action of Natural Selection 106

Divergence of Character 108

Evolution of the Human Eye 110

VI.

GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS.

Isolated Continents never were united 115

Means of Dispersal 116

These Means of Transport not accidental 118

Dispersal during the Glacial Period 119

The Theory of Creation inadequate 122

Causes of a Glacial Climate 123

Difficulties not yet removed 124

Identity of the Species of Islands with those of the Mainland
explained only by this Theory 125