204 The Palaeontological Record. II. Plants 



Darwin's argument that "the inhabitants of the world at each 

 successive period in its history have beaten their predecessors in the 

 race for life, and are, in so far, higher in the scale 1 " is unanswerable, 

 but we must remember that "higher in the scale" only means "better 

 adapted to the existing conditions." Darwin points out 2 that species 

 have remained unchanged for long periods, probably longer than the 

 periods of modification, and only underwent change when the con- 

 ditions of their life were altered. Higher organisation, judged by 

 the test of success, is thus purely relative to the changing conditions, 

 a fact of which we have a striking illustration in the sudden in- 

 coming of the Angiosperms with all their wonderful floral adaptations 

 to fertilisation by the higher families of Insects. 



II. Phylogeny. 



The question of phylogeny is really inseparable from that of the 

 truth of the doctrine of evolution, for we cannot have historical 

 evidence that evolution has actually taken place without at the same 

 time having evidence of the course it has followed. 



As already pointed out, the progress hitherto made has been 

 rather in the way of joining up the great classes of plants than in 

 tracing the descent of particular species or genera of the recent flora. 

 There appears to be a difference in this respect from the Animal 

 record, which tells us so much about the descent of living species, 

 such as the elephant or the horse. The reason for this difference is 

 no doubt to be found in the fact that the later part of the palaeonto- 

 logical record is the most satisfactory in the case of animals and the 

 least so in the case of plants. The Tertiary plant-remains, in the 

 great majority of instances, are impressions of leaves, the conclusions 

 to be drawn from which are highly precarious ; until the whole 

 subject of Angiospermous paleobotany has been reinvestigated, it 

 would be rash to venture on any statements as to the descent of the 

 families of Dicotyledons or Monocotyledons. 



Our attention will be concentrated on the following questions, all 

 relating to the phylogeny of main groups of plants : i. The Origin of 

 the Angiosperms. ii. The Origin of the Seed-plants, iii. The Origin 

 of the different classes of the Higher Cryptogamia. 



i. The Origin of tJie Angiosperms. 



The first of these questions has long been the great crux of 

 botanical phylogeny, and until quite recently no light had been 

 thrown upon the difficulty. The Angiosperms are the Flowering- 

 Plants, par excellence, and form, beyond comparison, the dominant 



1 Origin of Species, p. 315. 2 Ibid. p. 279. 



