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 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^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 



