viii 



TABLE OF CONTENTS 



CHAPTER III 



THE MENDELIAN PRINCIPLES OF HEREDITY 

 AND THEIR BEARING ON SEX 



1. Mendel's Discoveries 



2. The Heredity op^ One Pair of Characters . 



3. The Heredity of a Sex-linked Character . 



4. The Heredity of Two Pairs of Characters 



5. The Heredity of Two Sex-linked Characters 



6. A Theory of Linkage 



7. Three Sex-linked Factors .... 



PAGES 



73-7.5 



75-80 

 80-84 

 84-88 

 88-93 

 93-97 

 98-100 



CHAPTER IV I 



SECONDARY SEXUAL CHARACTERS AND THEIR 

 RELATION TO DARWIN'S THEORY OF SEX- 

 UAL SELECTION 



1. The Occurrence of Secondary Sexual Charac- 



ters in the Animal Kingdom .... 101-112 



2. Courtship 112-120 



3. Vigor and Secondary Sexual Characters . . 120-121 



4. Continuous Variation as a Basis for Selection 121-125 



5. Discontinuous Variation or Mutation as a Basis 



for Selection 125-131 



CHAPTER V 



THE EFFECTS OF CASTRATION AND OF TRANS- 

 PLANTATION ON THE SECONDARY SEXUAL 

 CHARACTERS 



1. Operations on Mammals 132-141 



2. Operations on Birds . 



3. Operations on Amphibia 



4. Internal Secretions . 



5. Operations on Insects 



6. Parasitic Castration of Crustacea 



142-144 

 145-146 

 146-147 

 148-1.55 

 155-1.58 



