Unity of Type Morphology Embryology Attempt to explain the facts of embryology On the graduated complexity in each great class Modification by selection of the forms of immature animals Importance of embryology in classification Order in time in which the great classes have first appeared 214-230 CHAPTER IX ABORTIVE OR RUDIMENTARY ORGANS. The abortive organs of Naturalists The abortive organs of Physiologists Abortion from gradual disuse 231-238 CHAPTER X RECAPITULATION AND CONCLUSION. Recapitulation Why do we wish to reject the Theory of Common Descent? Conclusion 239-255 Index 257 Portrait frontispiece Facsimile to face p. 50 ON THE ORIGIN OF SPECIES. OR THE PRESERVATION OF FAVOURED RACES IN THE STRUGGLE FOR LIFE. By Charles Darwin, CONTENTS DETEAILED CONTENTS. ON THE ORIGIN OF SPECIES. INTRODUCTION. 1. VARIATION UNDER DOMESTICATION. 2. VARIATION UNDER NATURE. 3. STRUGGLE FOR EXISTENCE. 4. NATURAL SELECTION 5. LAWS OF VARIATION. 6. DIFFICULTIES ON THEORY. 7. INSTINCT. 8. HYBRIDISM. 9. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. 10. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS. 11. GEOGRAPHICAL DISTRIBUTION. 12. GEOGRAPHICAL DISTRIBUTION—continued. 13. MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY: 14. RECAPITULATION AND CONCLUSION. ON THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION, OR THE PRESERVATION OF FAVOURED RACES IN THE STRUGGLE FOR LIFE By CHARLES DARWIN CONTENTS. INDEX INTRODUCTION Page 1 CHAPTER I. Variation under Domestication. Causes of Variability—Effects of Habit—Correlation of Growth—Inheritance—Character of Domestic Varieties—Difficulty of distinguishing between Varieties and Species—Origin of Domestic Varieties from one or more Species—Domestic Pigeons, their Differences and Origin—Principle of Selection anciently followed, its Effects—Methodical and Unconscious Selection—Unknown Origin of our Domestic Productions—Circumstances favourable to Man's power of Selection 7-43 CHAPTER II. Variation under Nature. Variability—Individual differences—Doubtful species—Wide ranging, much diffused, and common species vary most—Species of the larger genera in any country vary more than the species of the smaller genera—Many of the species of the larger genera resemble varieties in being very closely, but unequally, related to each other, and in having restricted ranges 44-59 CHAPTER III. Struggle for Existence. Its bearing on natural selection—The term used in a wide sense—Geometrical powers of increase—Rapid increase of naturalised animals and plants—Nature of the checks to increase—Competition universal—Effects of climate—Protection from the number of individuals—Complex relations of all animals and plants throughout nature—Struggle for life most severe between individuals and varieties of the same species; often severe between species of the same genus—The relation of organism to organism the most important of all relations