PREFACE 



This Third Volume completes a prolonged study of the great Class of the 

 Filicales by the author: but the whole work only marks a stage in their 

 detailed investigation. Historically there came first the period of discovery, 

 diagnosis, and description, together with a provisional systematic grouping 

 of the Class. The conclusion of this period may be held to have coincided 

 with the publication of the Origin of Species. The state of knowledge of the 

 Ferns at that time is fitly revealed in the First Edition of the Synopsis 

 Filiaini (1865), itself based upon the five volumes of Sir William Hooker's 

 Species Filicuni, of earlier date. Though the author of the Synopsis in his 

 Preface makes no reference to Darwin's work, he does remark that "here as 

 with other scientific systems those are the best characters which lead to a 

 knowledge of the object sought for in the nearest and clearest way, keeping 

 in view as much as possible its natural affinities." Nevertheless the goal of 

 the Synopsis was primarily to form "a useful vade viecuni for the travelling 

 botanist and the cultivator of Ferns, and for ready consultation in the 

 Herbarium." Thus was reflected in its pages the cataloguing aim of the 

 earlier phases of Pteridology. 



Already, however, the more penetrating spirit of Hofmeister was abroad. 

 His Vergleichende Untersuc/in/ig-en, puhVished in 185 1, revised and enlarged 

 in the English Translation of 1862, was coeval with the appearance of the 

 Origin of Species. These works of Hofmeister threw into coherent form the 

 results of that laboratory enquiry which was needed to supplement the use 

 of the hebarium, the garden, and the open countr)'. In particular it brought 

 into prominence the whole diplobiontic life-story, and provided a fresh 

 stimulus for the observation of that wider field of characters the want of 

 which in Cryptogams Sir William Hooker had deplored in his Preface to 

 the Synopsis (p. xi). Not only was this ground traversed by the observers 

 of detail in the living plant — particularly in Germany — but minute observa- 

 tion was soon to be directed more intensively than ever upon the correlative 

 fossils, particularly in France and in Britain. The result has been to show with 

 a high degree of certainty that those Ferns which have been designated b)- 

 Von Goebel the Eusporangiatae represent a more archaic type than those 

 which he had styled the Leptosporangiatae. Thus the way was being paved 

 during the period succeeding the appearance of the Origin of Species for a 

 grouping of Ferns that should reflect truly the broader lines of their evolution. 

 The results of this second period in the study of Ferns, together with that 

 of Archegoniate plants generally, were summed up in The Origin of a Land 

 Flora, published in 1908. Here a theory, based upon the facts of alternation, 



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