CONTENTS 

 EXPERIMENTAL STUDY OF EVOLUTION 



CHAPTER I 

 INTRODUCTION 



PAGE 



The Experimental Method 3 



CHAPTER II 



The Influence of External Conditions in causing Changes in the 



Structure of Animals 12 



Adaptive Responses 12 



Non-adaptive Responses 15 



Influence of Temperature on the Coloration of Butterflies . . 15 



Effect of Temperature on Caterpillars 24 



CHAPTER III 



The Influence of External Conditions in causing Changes in the 



Structure of Animals (^Continued) 29 



Experiments on the Influence of the Food Plant 29 



The Influence of Light, Electricity, Centrifugal Force, Chemical Sub- 

 stances, and Oxygen on the Caterpillars and Pupae of Moths and 



Butterflies 37 



The Influence of Humidity on the Characters of Moths and Butterflies 38 



Experiments with Flatfish 40 



Experiments with Crustaceans 40 



Changes in Mammals and Birds 41 



CHAPTER IV 

 The Inherited Effects of Changes induced by External Factors 43 



CHAPTER V 



The Inheritance of Acquired Characters 50 



Telegony 59 



Xenia ............. 61 



Theories of Transmission of Somatic Influences 61 



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