CONTENTS. 



PAGE 



TRANSLATOR'S PREFACE v 



INTRODUCTION 1 



DEVELOPMENT OF THE EMBRYO . . . . . 11 

 THE SPAWNING, AND THE DURATION, OF DEVELOPMENT IN 



THE EMBRYO 26 



FIRST PERIOD OF DEVELOPMENT ... 43 



SECOND PERIOD OF DEVELOPMENT 56 



THIRD PERIOD OF DEVELOPMENT . ... 67 



FOURTH PERIOD OF DEVELOPMENT . . . 129 



FIFTH PERIOD OF DEVELOPMENT 159 



EXPLANATION OF THE FIGURES . . 166 



SIGNIFICATION OF LETTERS IN PLATES 181 



