LEfNEAN SOCIETY OF LONDOX. 29 



the word " higher," more perfectly adapted to the existing coudi- 

 tions, then it would be very difficult to prove any advance, for as I 

 have endeavoured to show, adaptation has in ever}-^ age been fully 

 adequate in relation to the prevailing conditions. If organisms 

 have grown in complexity, it is only where the conditions of their 

 life have become more complex. The most striking examples of 

 high organization in relation to organic environment are presented 

 by the characteristic modern sub-kingdom, the Augiosperms, in 

 the evolution of which, as ISaporta pointed out, insect-fertilization 

 has been the chief determining factor, leading to an infinite 

 variety in the special adaptations of the flower and no doubt 

 indirectly affecting the mode of life of the whole plant. The 

 advent of the Angiosperms seems to have been almost simultaneous 

 Avith that of the higher families of insects, which now, at all 

 events, are chiefly concerned in pollination. It would be difficult 

 to overestimate the importance of these relations in their elfect 

 on the Flora of the world. If the vegetation of our own epoch 

 appears, on the whole, definitely more advanced than that of 

 earlier geological periods, this is probably due in a greater degree 

 to the contemporary insect-life than to any other cause. 



Unfortunately we have very little knowledge of the special 

 adaptations of the plants of the distant past — in particular, we 

 know scarcely anything of their relations to other organisms. 

 The presence of characteristic glands on the surface of some 

 Palaeozoic plants (notably the Fern-like seed-plant Lyginodendron') 

 has suggested that insects may have been attracted, who were in 

 some way useful to the plant. At the same time the immense 

 number of pollen-grains found in the pollen-chambers of the seed 

 in plants of this group has roused the suspicion that some agent 

 more certain than the wind may have been concerned, and that 

 possibly insect-pollination may have had its beginnings nuich 

 further back in the evolution of seed-plants than we have been 

 accustomed to think. The suggestion was due to Sir Joseph 

 Hooker, and has received support from evidence recently adduced 

 that living Cycads * and also Wehvitschiaf (plants which belong, 

 in a sense, to the past rather than the present) may employ insects 

 as carriers of pollen. But as regards the fossil plants the data 

 are still insufficient. In any case we must grant the superiority, 

 from this point of view, of the more modern types. 



I have discussed the subject of reduction in evolution else- 

 where X and will only briefly allude to it here. In many groups 

 (Lycopods, Equisetales, Cycadophytes) there has been a lowering 

 of the standard of organization, partly due to direct reduction, 

 partly to the extinction of the higher forms in each group. There 



* Pearson, H. H. W.. " Notes on South African Cycads," Trans. South African 

 Phil. Soc. vol. xvi (1906^ p. 348. 



t Pearson, H. H. W.. '• Some Observations on Welwitschia mirabilis," Phil. 

 Trans. Royal Soc. (B^ vol. 198, lOOfi, p. 274. 



\ ' Darwin and Modern Science.' XIT. The Palaeontological Record. II. 

 Plants. 1909. 



