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EVOLUTION AND ADAPTATION

PREFACE

CONTENTS

Structural Adaptations

Adjustments of the Individual to Changes in the Environment

Adaptations for the Good of the Species

Organs of Little Use to the Individual

Changes in the Organism that are of No Use to the Individual or to the Race

Comparison with Inorganic Phenomena

Evidence in Favor of the Transmutation Theory

THE GEOLOGICAL EVIDENCE

EVIDENCE FROM DIRECT OBSERVATION AND EXPERIMENT

MODERN CRITICISM OF THE THEORY OF EVOLUTION

Conclusions

Variation and Competition in Nature

The Theory of Natural Selection

Sterility between Species

Weismann’s Germinal Selection

General Criticism of the Theory of Sexual Selection

Darwin’s Hypothesis of Pangenesis

The Neo-Lamarckian School

Continuous Variation

Frequency of Different Types of Beech Leaves

Heredity and Continuous Variation

Discontinuous Variation

The Mutation Theory of De Vries

Conclusions

The Effect of External Influences

Responsive Changes in the Organism that adapt it to the New Environment

Nägeli’s Perfecting Principle

Form and Symmetry

Mutual Adaptation of Colonial Forms

Degeneration

Protective Coloration

Length of Life as an Adaptation

Organs of Extreme Perfection

Secondary Sexual Organs as Adaptations

Individual Adjustments as Adaptations

Color Changes as Individual Adaptations

Increase of Organs through Use and Decrease through Disuse

Reactions of the Organism to Poisons, etc.

Regeneration

The Different Kinds of Sexual Individuals

The Determination of Sex

Sex as a Phenomenon of Adaptation

INDEX