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 



SUMMABY ... 27 



CHAFTEB II. 



THE PHENOMENA OF THE MATURATION OF THE EGG AND THE 

 PROCESS OF FERTILISATION ... 



The Phenomena op Maturation . 



Historical 



The Process of Fertilisation ..... 



Historical . .... 



Summary .... 



30 

 30 

 35 

 37 

 45 

 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 



(GASTRiEA-THEORY) . . ... . . 84 



CHAPTER VI. 



THE DEVELOPMENT OF THE TWO MIDDLE GERM -LAYERS 



(C(ELOM-THEORY) ... 106 



Summary ... 142 



CHAPTER VII. 

 HISTORY OF THE GERM-LAYER THEORY 145 



CHAPTER VIII. 



DEVELOPMENT OF THE PRIMITIVE SEGMENTS . . . .161 

 Summary . . 169 



