TABLE 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 116 



VI. Variation and Locality 118 



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 



XI. The Sterility of Hybrids. Concluding Re- 

 marks 233 



Index 251 



