CONTENTS 



EXPERIMENTAL STUDY OF EVOLUTION 



CHAFFER 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 HI 



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 



vii 



