CONTENTS 



page 



PREFACE VII 



I INTRODUCTION 1 

 II THE INITIATION OF DEVELOPMENT: THE 



FERTILISATION OF THE EGG 7 



III THE STRUCTURE OF THE FERTILISED EGG 27 



IV POLARITY AND SYMMETRY; GRADIENT- 



FIELDS 39 



V CHEMODIFFERENTIATION 50 

 VI THE REALISATION OF THE NUCLEAR 



FACTORS 64 



Vn THE TOPOGENESIS OF THE EMBRYO 91 



VIII INDUCTION AND ORGANISATION : 



I. NEURULATION 106 



IX INDUCTION AND ORGANISATION: 



II. THE PERIOD OF ORGAN DEVELOPMENT 128 



X THE LATER STAGES OF DEVELOPMENT 151 



XI REGENERATION 160 



Xn SOME FINAL CONSIDERATIONS 182 



