Natural Selection 217 



majority of the supposed Ferns of that age having proved to be seed- 

 bearing plants. The oldest authentic representatives of the Ferns 

 were megaphyllous plants, broadly speaking, of the same type as 

 those of later epochs, though differing much in detail. As far back 

 as the record extends they show no sign of becoming merged with 

 other phyla in any synthetic group. 



The Equisetales likewise have a long history, and manifestly 

 attained their greatest development in Palaeozoic times. Their 

 oldest forms show an approach to the extinct class Sphenophyllales, 

 which connects them to some extent, by anatomical characters, with 

 the Lycopods. At the same time the oldest Equisetales show a 

 somewhat megaphyllous character, which was more marked in the 

 Devonian Fseudoborniales. Some remote affinity \nt\\ the Ferns 

 (which has also been upheld on other grounds) may thus be indicated. 

 It is possible that in the Sphenophyllales we may have the much- 

 modified representatives of a very ancient synthetic group. 



The Lycopods likewise attained their maximum in the Palaeozoic, 

 and show, on the whole, a greater elaboration of structure in their 

 early forms than at any later period, while at the same time maintain- 

 ing a considerable degree of uniformity in morphological characters 

 throughout their history. The Sphenophyllales are the only other 

 class with wliich they show any relation ; if such a connection existed, 

 the common point of origin must lie exceedingly far back. 



The fossil record, as at present known, cannot, in the nature of 

 things, throw any direct light on what is perhaps the most disputed 

 question in the morphology of plants — the origin of the alternating 

 generations of the higher Cryptogams and the Spermophyta. At the 

 earliest period to which terrestrial plants have been traced back all 

 the groups of Vascular Cryptogams were in a highly advanced stage 

 of evolution, while innumerable Seed-plants — presumably the descend- 

 ants of Cryptogamic ancestors — were already flourishing. On the 

 other hand we know practically nothing of Palaeozoic Bryophyta, 

 and the evidence even for their existence at that period cannot be 

 termed conclusive. AVliile there are thus no palaeontological grounds 

 for the hypothesis that the Vascular plants came of a Bryophytic 

 stock, the question of their actual origin remains unsolved. 



III. Natural Selection. 



Hitherto we have considered the palaeontological record of 

 plants in relation to Evolution. The question remains, whether 

 the record throws any light on the theory of which Darwin and 

 Wallace were the authors — that of Natural Selection. The subject 

 is clearly one which must be investigated by other methods than 



