CHAPTER XVIII. 



THE EVIDENCE FROM PALAEOPHYTOLOGY. 



IT has been remarked above (Chapter I.) that the only direct and positive 

 clue to the sequence of appearance of Plant-Forms in past time upon the 

 earth is to be obtained from the study of fossils. Luminous facts derived 

 from them are beginning to shed a fresh and direct light upon problems 

 hitherto obscure ; and the last quarter of a century especially has shown 

 how greatly a knowledge of the fossil forms may advance the true per- 

 ception of affinities of certain groups of plants now living. 



But the success which has already attended Palaeontological investi- 

 gation, and has led to such important results, must not be allowed to 

 disguise the limits which circumscribe this branch of enquiry : nor should 

 it unduly raise the hope that the area of fact available for comparison 

 with forms now living will be indefinitely extended. It can hardly be 

 anticipated that data derived from fossils will ever take a decisive place 

 in discussions of the primary origin of the sporophyte. In the mind 

 of the Morphologist there can be no spirit of depreciation of the recent 

 advances of Palaeophytology, but rather a very high estimate of their 

 value : nevertheless he cannot help recognising how inadequate the 

 evidence drawn from fossils is in its bearing on such questions as those 

 discussed in the foregoing chapters. Hitherto it has given no clue 

 whatever to the origin x of the Bryophyte sporogonium : nor does it 

 materially assist in resolving the problem of the origin of the leafy 

 sporophyte, or of its adoption of a free-living habit : nor, again, does it 

 indicate with any decisiveness the evolutionary relationships of the great 

 phyla of the early Pteridophytes. All these questions deal with events 

 which we may presume to have preceded the existence of the earliest 

 fossils of which any exact record has hitherto been discovered. 1 



1 I am unable to share the very sanguine view of Mr. Arber (Annals of Botany, 1906, 

 p. 216), who remarks that " the imperfection of the Record, largely exaggerated in the 

 past, can be wholly neglected where we are considering the larger divisions of the vege- 

 table kingdom, such as phyla, classes, or groups of Plants." 



