vi ' • * - PREFACE 



urged that the several sequences of facts may be so linked into a coherent 

 web that they will mutually support or check one another. It should be the 

 constant practice of the morphologist to use them in this way. Stability will 

 thus be given to the more general conclusions, and these will be based not 

 upon preconceptions but upon the orderly use of "experience and particulars." 



The Class of the Filicales stands pre-eminent as a field for the practice 

 of this inductive method. It is represented by many thousands of living 

 species, spread over all quarters of the globe. These plants have characters 

 in common which seldom leave a doubt of the "Filical" nature of any species. 

 Nevertheless the Ferns vary so greatly, and, as it is found, so consistently in 

 their details that ample material is at hand for their comparison, and phyletic 

 seriation. Besides this the Class is so well represented among the fossils that 

 the sequences traced by comparison of living types may often be effectively 

 checked by the order of occurrence of the several forms in the successive 

 geological strata. But such a study of Ferns with a view to visualising their 

 own inter-relationships need not be the sole aim before us here. If their 

 comparison leads to a clear conception of some general type of primitive 

 organisation from which in the long distant past the whole phylum may have 

 sprung, this should serve to indicate probable relationships with other primi- 

 tive phyla: and so the comparative study of their phylesis may contribute 

 to still wider views on the Descent of Land-Living Plants. This has been 

 in part the aim of the author in undertaking the present work. Primarily 

 it is a treatise on the Filicales : but secondarily, it will touch broader questions 

 of Morphology and of Evolution. 



It has not been the author's intention to give an exhaustive summary of 

 all knowledge relating to Ferns, nor will complete citations of the profuse 

 literature of the subject be attempted. Instead of this, when works of other 

 writers are quoted in which a special branch of the literature is fully cited, 

 the fact \v\\\ be noted. Readers will thus be given clues to the whole litera- 

 ture, which may readily be followed up by them ; while the present volume 

 will be relieved of much unnecessary print. 



Where illustrations have been borrowed the debt is acknowledged in the 

 legends, and here grateful thanks are accorded to their authors ; some parti- 

 cular acknowledgments appear on p. viii. A large proportion of the figures 

 in this book are original, and to them no author's name is attached. In the 

 production of these, and in the general illustration of this volume, the author 

 desires to acknowledge substantial assistance given by the Carnegie Trustees. 

 By aiding the publication of results obtained during the present period of 

 high prices, they promote the advancement of Science in a most practical way, 

 and deserve not only the thanks of the immediate recipient, but the general 

 regard of men of Science. 



F. O. BOWER. 



Glasgow, 



December^ 1922. 



