CONTENTS. 



CHAPTER I. Page 



Introductory Remarks 1 



CHAPTER II. 



Fact of Variation 7 



As a matter of experience 8 



As probable from analogy 10 



CHAPTER III. 



Causes of Variation 19 



§ 1. Climatal causes generally (whether dependent 



upon latitude or upon altitude) 23 



§2. Temporary heat or cold, of an unusual degree ... 42 



§ 3. Nature of the country, and of the soil 46 



§ 4. Isolation ; and exposure to a stormy atmosphere . 70 



CHAPTER IV. 



Organs and Characters of Variation 95 



CHAPTER V. 



Geological Reflections Ill 



CHAPTER VI. 



The Generic Theory 157 



CHAPTER VII. 



Conclusion 181 



