The Truth of Evolution 201 



the last section of this essay) or must still rely on Darwin's explana- 

 tion of the absence of numerous intermediate varieties. The attempts 

 which have been made to trace, in the Tertiary rocks, the evolution 

 of recent species, cannot, owing to the imperfect character of the 

 evidence, be regarded as wholly satisfactory. 



When we come to groups of a somewhat higher order we have 

 an interesting history of the evolution of a recent family in the 

 work, not yet completed, of Kidston and Gwynne-Vaughan on the 

 fossil Osmundaceae l . The authors are able, mainly on anatomical 

 evidence, to trace back this now limited group of Ferns, through the 

 Tertiary and Mesozoic to the Permian, and to show, with great 

 probability, how their structure has been derived from that of early 

 Palaeozoic types. 



The history of the Ginkgoaceae, now represented only by the 

 isolated maidenhair tree, scarcely known in a wild state, offers 

 another striking example of a family which can be traced with 

 certainty to the older Mesozoic and perhaps further back still 2 . 



On the wider question of the derivation of the great groups 

 of plants, a very considerable advance has been made, and, so far 

 as the higher plants are concerned, we are now able to form a far 

 better conception than before of the probable course of evolution. 

 This is a matter of phylogeny, and the facts will be considered under 

 that head; our immediate point is that the new knowledge of the 

 relations between the classes of plants in question materially 

 strengthens the case for the theory of descent. The discoveries 

 of the last few years throw light especially on the relation of the 

 Angiosperms to the Gymnosperms, on that of the Seed-plants gener- 

 ally to the Ferns, and on the interrelations between the various 

 classes of the higher Cryptogams. 



That the fossil record has not done still more for Evolution is due 

 to the fact that it begins too late a point on which Darwin laid 

 stress 3 and which has more recently been elaborated by Poulton 4 . 

 An immense proportion of the whole evolutionary history lies behind 

 the lowest fossiliferous rocks, and the case is worse for plants than 

 for animals, as the record for the former begins, for all practical 

 purposes, much higher up in the rocks. 



It may be well here to call attention to a question, often over- 

 looked, which has lately been revived by Reinke 5 . As all admit, 



1 Trans. Royal Soc. Edinburgh, Vol. 45, Pt. in. 1907, Vol. 46, Pt. 11. 1908, Vol. 46, 

 Pt. in. 1909. 



2 See Seward and Gowan, "The Maidenhair Tree (Ginkgo biloba)," Annals of Botany, 

 Vol. xiv. 1900, p. 109; also A. Sprecher, Le Ginkgo biloba L., Geneva, 1907. 



3 Origin of Species (6th edit.), p. 286. 



4 Essays on Evolution, pp. 46 et seq., Oxford, 1908. 



5 Reinke, loc. cit. p. 13. 



