CONTENTS. XI 



Concluding Remarks Continued. 



Isolation Usually Discriminate and therefore Segregative from the 



First 1 74 



Intensive Segregation put in the Next Paper 174 



Table of Forms of Segregation 176 



Computation of Effects of Positive and Negative Segregation 177-183 



Table III 179 



Table V 182 



APPENDIX II. INTENSIVE SEGREGATION. 



[From the Linnean Society's Journal, Zoology, vol. xxni.] 



Classification of the Forms of Intensive Segregation 185-212 



Separation Always Involves More or Less Segregation 1 86 



Eight Principles of Monotypic Evolution 187 



Certain Laws of Growth not here Discussed 189 



The Transformation of Freely Intergenerating Organisms never 



Permanently Divergent 191 



Independent Transformation Always Divergent 191 



Pervasive Influence of Causes of Transformation 192 



Utilitarian and Non-Utilitarian Divergence 194 



Selectional Intension and Its Forms 195-207 



Indiscriminate Eh'minational Intension 209 



Amalgamational Intension 211 



Combined Influence of These Principles 212 



Divergence of Mollusks . . .* 212-224 



Divergent Evolution in the Snails of Oahu 213-222 



Similar Facts Concerning Land-mollusks of < Hher Regions 224 



Divergence in Insects 225-234 



Divergence in Erynnis and Thanaos 225 



Divergent Species of Basilarchia 225 



Divergence in the Periodical Cicada 229 



Concluding Remarks 234-243 



Outline of the Argument in Support of Divergence through Cumu- 

 lative Segregation 234 



Reply to Criticism 236 



Construction of Permutational Triangle 241 



APPENDIX III. LETTERS. 



[Published in " Nature," April 10, May 8, and August 14, 1890, and April 1, 1897.] 



" Like to Like" a Fundamental Principle in Bionomics 245-249 



Laws of Heredity 249 



Local Segregation Often Initiates Divergence 247 



Permanent Difference in Innate Adaptations not Necessarily Ad- 

 vantageous Difference 248 



Unstable Adjustments as Affected by Isolation 249-252 



Indiscriminate Separation, Under the Same Environment, a Cause of 



Divergence 252-2 55 



