CONTENTS. 



PAGE 



INTRODUCTION 1 



MANUALS AND TEXT-BOOKS . ' 4 



PART FIRST. 

 CHAPTER I. 



DESCRIPTION OP 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 OF 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^EA-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 



