TABLES OF CONTENTS. 



CHAPTER PAGE 



I. INTRODUCTORY. THE PROBLEM OF SPECIES AND 



VARIETY i 



II. MERISTIC PHENOMENA 31 



III. SEGMENTATION, ORGANIC AND MECHANICAL 60 



IV. THE CLASSIFICATION OF VARIATION AND THE NATURE 



OF SUBSTANTIVE VARIATION 83 



NOTE TO CHAPTER IV 94 



V. THE MUTATION THEORY 97 



NOTE TO CHAPTER V 1 16 



VI. VARIATION AND LOCALITY 1 18 



VII. LOCAL DIFFERENTIATION continued. OVERLAPPING 



FORMS 146 



VIII. LOCALLY DIFFERENTIATED FORMS continued. CLI- 

 MATIC VARIETIES 164 



IX. THE EFFECTS OF CHANGED CONDITIONS 187 



X. THE EFFECTS OF CHANGED CONDITIONS continued. 



THE CAUSES OF GENETIC VARIATION 212 



XL THE STERILITY OF HYBRIDS. CONCLUDING RE- 

 MARKS 233 



APPENDIX TO CHAPTER X 250 



INDEX . 251 



IX 



