TABLE OF CONTENTS 



Introduction 



PAGES 



v-vi 



CHAPTER I 

 THE EVOLUTION OF SEX 



1. Reproduction, a Distinctive Feature of Living 



Things 1-4 



2. The "Meaning" of Sexual Reproduction . . . 4-15 



3. The Body and the Germ-plasm .... 15-19 



4. The Early Isolation of the Germ-cells . . 20-23 



5. The Appearance of the Accessory Organs of 



Reproduction 23-26 



6. The Secondary Sexual Characters . . . 26-31 



7. The Sexual Instincts 31-34 



CHAPTER II 



THE MECHANISM OF SEX-DETERMINATION 



1. The Maturation of the Egg and the Sperm . 35-40 



2. The Cytological Evidence 40-54 



a. Protenor ........ 11-14 



h. Lygaeus 41-16 



c. Oncopeltus 46-48 



d. Ascaris . 49-52 



e. Aphids and Phylloxerans ..... 52-54 



3. The Experimental Evidence 55-72 



a. The Experiments on Sea-urchins' Eggs . . 55-63 



b. The Evidence from Sex-linked Inheritance . 63-72 H 



vii 



