CONTENTS
CHAPTER I
| PAGE | |
| The Problem of Adaptation | [1] |
| – Structural Adaptations | [1] |
| – Adaptations for the Good of the Species | [19] |
| – Organs of Little Use to the Individual | [22] |
| – Changes in the Organism that are of No Use to the Individual or to the Race | [25] |
| – Comparison with Inorganic Phenomena | [26] |
CHAPTER II
| The Theory of Evolution | [30] |
| – Evidence in Favor of the Transmutation Theory | [32] |
| – – Evidence from Classification and from Comparative Anatomy | [32] |
| – – The Geological Evidence | [39] |
| – – Evidence from Direct Observation and Experiment | [43] |
| – – Modern Criticism of the Theory of Evolution | [44] |
CHAPTER III
| The Theory of Evolution (continued) | [58] |
| – The Evidence from Embryology | [58] |
| – – The Recapitulation Theory | [58] |
| – Conclusions | [84] |
CHAPTER IV
| Darwin’s Theories of Artificial and of Natural Selection | [91] |
| – The Principle of Selection | [91] |
| – Variation and Competition in Nature | [104] |
| – The Theory of Natural Selection | [116] |
CHAPTER V
| The Theory of Natural Selection (continued) | [129] |
| – Objections to the Theory of Natural Selection | [129] |
| – Sterility between Species | [147] |
| – Weismann’s Germinal Selection | [154] |
CHAPTER VI
| Darwin’s Theory of Sexual Selection | [167] |
| – Sexual Selection | [167] |
| – General Criticism of the Theory of Sexual Selection | [213] |
CHAPTER VII
| The Inheritance of Acquired Characters | [222] |
| – Lamarck’s Theory | [222] |
| – Darwin’s Hypothesis of Pangenesis | [233] |
| – The Neo-Lamarckian School | [240] |
CHAPTER VIII
| Continuous and Discontinuous Variation and Heredity | [261] |
| – Continuous Variation | [261] |
| – Heredity and Continuous Variation | [270] |
| – Discontinuous Variation | [272] |
| – Mendel’s Law | [278] |
| – The Mutation Theory of De Vries | [287] |
| – Conclusions | [297] |
CHAPTER IX
| Evolution as the Result of External and Internal Factors | [300] |
| – The Effect of External Influences | [300] |
| – Responsive Changes in the Organism that adapt it to the New Environment | [319] |
| – Nägeli’s Perfecting Principle | [325] |
CHAPTER X
| The Origin of the Different Kinds of Adaptations | [340] |
| – Form and Symmetry | [340] |
| – Mutual Adaptation of Colonial Forms | [350] |
| – Degeneration | [352] |
| – Protective Coloration | [357] |
| – Sexual Dimorphism and Trimorphism | [360] |
| – Length of Life as an Adaptation | [370] |
| – Organs of Extreme Perfection | [371] |
| – Secondary Sexual Organs as Adaptations | [372] |
| – Individual Adjustments as Adaptations | [375] |
| – Color Changes as Individual Adaptations | [375] |
| – Increase of Organs through Use and Decrease through Disuse | [376] |
| – Reactions of the Organism to Poisons, etc. | [377] |
| – Regeneration | [379] |
CHAPTER XI
| Tropisms and Instincts as Adaptations | [382] |
CHAPTER XII
| Sex as an Adaptation | [414] |
| – The Different Kinds of Sexual Individuals | [414] |
| – The Determination of Sex | [422] |
| – Sex as a Phenomenon of Adaptation | [439] |
CHAPTER XIII
| Summary and General Conclusions | [452] |
| INDEX | [465] |
EVOLUTION AND ADAPTATION
CHAPTER I
THE PROBLEM OF ADAPTATION
Between an organism and its environment there takes place a constant interchange of energy and of material. This is, in general, also true for all bodies whether living or lifeless; but in the living organism this relation is a peculiar one; first, because the plant or the animal is so constructed that it is suited to a particular set of physical conditions, and, second, because it may so respond to a change in the outer world that it further adjusts itself to changing conditions, i.e. the response may be of such a kind that it better insures the existence of the individual, or of the race. The two ideas contained in the foregoing statement cover, in a general way, what we mean by the adaptation of living things. The following examples will serve to illustrate some of the very diverse phenomena that are generally included under this head.