TABLE OF CONTENTS xi 

 PART III. THE CAUSAL FACTORS OF ORGANIC EVOLUTION 



PAGE 



CHAPTER XIII. INTRODUCTORY STATEMENT ....... 185 



What We Owe to Darwin 186 



CHAPTER XIV. THE BACKGROUND OF DARWINISM 



ADAPTATIONS. H.H.N 188 



Laws of Adaptation 192 



Adaptations Classified 195 



Some Special Adaptations 196 



Parasitism and Degeneration 197 



Color in Animals 200 



CHAPTER XV. THE BACKGROUND OF DARWINISM Continued . . 206 



The Web of Life. /. Arthur Thomson 206 



CHAPTER XVI. NATURAL SELECTION. Charles Darwin . . . . 219 



Foundation Stones of Natural Selection 219 



Darwin's Own Estimate as to the Role of Natural Selection in 



Evolution 219 



Effects of Habits and the Use or Disuse of Parts; Correlated 



Variation; Inheritance 220 



Darwin's Idea of the Causes Responsible for the Origin of Domes- 

 tic Races 221 



Darwin's Idea of the Origin of Varieties, Species, and Genera irf 



Nature 221 



The Term "Struggle for Existence" Used in a Large Sense . . 222 



Geometrical Ratio of Increase 223 



Natural Selection; Or the Survival of the Fittest . . . . . 223 



Sexual Selection . 230 



Illustrations of the Action of Natural Selection, or the Survival 



of the Fittest 232 



Summary of Chapter on Natural Selection 233 



Difficulties and Objections to Natural Selection as Seen by Darwin 236 



CHAPTER XVII. CRITIQUE OF DARWINISM v . . 245 



Summary of Darwin's Natural-Selection Theory. Vernon L. 



Kellogg 245 



-Objections to Darwinism > . . 247 



Defense of Darwinism 252 



General Defense of Darwinism. /. L. Tayler . . . . , . . 253 



Experimental Support of the Effectiveness of Natural Selection . 256 



The Present Status of Natural Selection . . . . . - i' .- . 258 

 The Relation of Mendelism and the Mutation Theory to Natural 



Selection. C. C. Nutting . . . ; , . . -. . . ... 258 



