CONTENTS 



FOREWORD 



I. INTRODUCTION 13 



The development of animal organization- 

 similarity of all young embr)os— The 

 three fundamental layers 



II. THE BEGINNING OF DEVELOPMENT 26 



Egg and sperm— Fertilization, heredity, vir- 

 gin birth— Development begins 



III. MOVEMENTS AND FOLDINGS 40 



Formation of the three layers in sea- 

 urchins — Frogs and newts — Lampreys — 

 Birds— Mammals 



IV. THE "organization CENTER" 61 



The technique of micro-surgery — The 

 focus around which the embno is inte- 

 grated — Birds — Mammals — Sea-urchins 

 —Insects 



V. THE ADDITION OF DETAILS 78 



Secondary organization centers — Special 

 factories making special parts— Mosaic eggs 

 -Different ways of building up similar 

 structures— Larvae 



82513 



