CONTENTS. 



PAGE 



INTRODUCTION 1 



MANUALS AND TEXT-BOOKS 4 



PART FIRST. 



CHAPTER I. 

 DESCRIPTION OF THE SEXUAL PRODUCTS 7 



THE EGG-CELL 7 



THE SEMINAL FILAMENTS . . 19 



Historical . . . . .23 



SUMMARY . . .27 



CHAPTER II. 

 THE PHENOMENA OF THE MATURATION OF THE EGG AND THE 



PROCESS OF FERTILISATION 30 



THE PHENOMENA OP MATURATION 30 



Historical 35 



THE PROCESS OP FERTILISATION 37 



Historical 45 



SUMMARY 46 



CHAPTER III. 



THE PROCESS OF CLEAVAGE 51 



Historical 69 



SUMMARY 72 



CHAPTER IV. 



GENERAL DISCUSSION OF THE PRINCIPLES OF DEVELOPMENT 76 



CHAPTER V. 

 THE DEVELOPMENT OF THE TWO PRIMARY GERM-LAYERS 



(GASTR^A-THEORY) 84 



CHAPTER VI. 



THE DEVELOPMENT OF THE TWO MIDDLE GERM -LAYERS 



(CCELOM-THEORY) 106 



SUMMARY 142 



CHAPTER VII. 

 HISTORY OF THE GERM-LAYER THEORY 145 



CHAPTER VIII. 



DEVELOPMENT OF THE PRIMITIVE SEGMENTS . . .161 



SUMMARY . 169 



