PREFACE TO THE THIRD EDITION 



In the second edition of the ''Mosses and Ferns," the original 

 text was carefully revised, and a good deal of it was rewritten. 

 At the same time considerable new matter was added. In 

 preparing the present edition of the book, it has not seemed 

 necessary to change the body of the text, the new material being 

 given in the form of an appendix. 



Since the publication of the last edition, as might be expected, 

 numerous contributions have been made to the literature of the 

 Morphology and Classification of the Archegoniates. Among 

 these contributions are several publications by the writer. These 

 are for the most part based upon collections of tropical Liverworts 

 and Ferns made by the writer, including some new and rare 

 species of the Indo-Malayan region. 



A summary of the more important results of these studies as 

 well as those of other investigators is added to the text in the 

 form of an appendix, in which the new material is arranged 

 under the Chapter headings which deal with the allied topics 

 in the main text. In the appendix, also, certain errors of state- 

 ment and reference in the original text have been corrected. 



The numerous additions in the literature on the subject have 

 necessitated a complete revision of the bibHography, which has 

 been very considerably enlarged. 



It is hoped that with the appendix and augmented bibliog- 

 raphy the book will prove a satisfactory statement of our present 

 knowledge of the structure and development of the Archegoniate 



Plants. 



DOUGLAS HOUGHTON CAMPBELL. 



Stanford University, 

 January, 1918. 



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