CONTENTS 



CHAPTER L 

 ISOLATION i 



CHAPTER II. 

 ISOLATION (continued) 28 



CHAPTER III. 

 PHYSIOLOGICAL SELECTION .41 



CHAPTER IV. 

 EVIDENCES OF PHYSIOLOGICAL SELECTION ... 62 



CHAPTER V. 

 FURTHER EVIDENCES OF PHYSIOLOGICAL SELECTION . 81 



CHAPTER VI. 



A BRIEF HISTORY OF ISOLATION AS A FACTOR IN 

 ORGANIC EVOLUTION 101 



GENERAL CONCLUSIONS . 144 



APPENDIX A. MR. GULICK'S CRITICISM OF MR. WALLACE'S 

 VIEWS ON PHYSIOLOGICAL SELECTION . . .151 



