CHAPTER I. VARIATION UNDER DOMESTICATION. - - Character of Causes of Variability-Effects of Habit and the use or disuse of .. 7 - CHAPTER II. VARIATION UNDER NATURE. Variability Individual differences - Doubtful species Wide 51 CHAPTER III. STRUGGLE FOR EXISTENCE. Its bearing on natural selection—The term used in a wide sense- Page 75 CHAPTER IV. NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST. 97 CHAPTER V. LAWS OF VARIATION. Effects of changed conditions-Use and disuse, combined with tion-Correlated variation-Compensation and economy of CHAPTER VI. DIFFICULTIES OF THE THEORY. Difficulties of the theory of descent with modification-Absence or 207 CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL Longevity-Modifications not necessarily simultaneous-Modifica- 262 CHAPTER VIII. INSTINCT. Instincts comparable with habits, but different in their origin—. Page 319 |