CONTENTS 



INTRODUCTION 



PAGE 



HISTORICAL SURVEY OF THEORIES OR SUGGESTIONS OF 



CHEMICAL INFLUENCE IN HEREDITY . . xi 



CHAPTER I 



CLASSIFICATION AND ADAPTATION ... 1 



CHAPTER II 



MENDELISM AND THE HEREDITY OF SEX . . .39 



CHAPTER III 



INFLUENCE OF HORMONES ON DEVELOPMENT OF SOMATIC 



SEX-CHARACTERS . . . . .67 



CHAPTER IV 



ORIGIN OF SOMATIC SEX-CHARACTERS IN EVOLUTION . .107 



CHAPTER V 



MAMMALIAN SEXUAL CHARACTERS. EVIDENCE OPPOSED TO 



THE HORMONE THEORY . . . .134 



vii 



