xii CONTENTS 



PART III. THE EVOLUTION AND PHYLOGENY 

 OF THE GROUP 



CHAPTER PAGE 



IX. The Evolution of Structures 141 



The Evolution of the Cone 141 



The Evolution of the Female Gametophyte .... 153 



The Evolution of the Male Gametophyte . . , . 156 



Emhryogeny i57 



The Leaf 161 



The Stem 161 



The Root 162 



X. Lines of Evolution 163 



Index 171 



