part 2] ANNIVEBSAEY ADDEESS OF THE PRESIDENT, lxxxix 



is very difficult to draw, both in the Northern and in the Southern 

 Hemisphere. 



The discovery by Dr. W. Mackie, a few years ago, of a bed of 

 chert in Aberdeenshire, almost certainly of Middle Devonian age, 

 may be compared in importance and in its effect upon the imagi- 

 nation with the more recent discovery of the burial-chambers of 

 Tutankhamen in the Valley of the Kings. Subsequent exposure 

 of the Bhynie dej>osit by the Geological Survey, and the admirable 

 botanical work of Kidston & Lang enable us to reconstruct a 

 Devonian peat-bog ; to see the sunlight on the pools of a swamp 

 covered with diminutive green forests, some plants fully exposed 

 to the air, others partly submerged, streams carrying in solution 

 silica furnished by neighbouring fumaroles which was to seal up 

 for us ' after-thoughts of creation,' samples of a peat-forming 

 vegetation and of a microscopic flora of saprophytic fungi, 

 bacteria, and Blue-Green Algse strangely similar in the plan of 

 their construction to recent forms, yet in certain features bearing 

 the impress of an early phase of evolution. ' The key of the past, 

 as of the future, is to be sought in the present ' : these words of 

 Huxley find an illustration in the interpretation of the anatomy 

 of fossil plants. The extent of our ability to correlate the 

 structural details of the framework of a living plant, and the 

 activities of which they are the expression, is a measure of 

 accuracy by which we can endow with life the petrified stems from 

 ' the dark backward and abysm of time ' and visualize the plants as 

 machines at work. 



The Bhynie plants, although not the oldest-known representa- 

 tives of Devonian vegetation, will be considered first, because our 

 knowledge of them is relatively complete. Excellent summaries 

 of the researches of Kidston & Lang by Dr. D. H. Scott (' Studies 

 in Fossil Botany ' 3rd ed. 1920), Prof. F. 0. Bower ( ; Nature ' 

 July 29th, 1920), and other authors render it unnecessary for me 

 to do more than call attention to the salient features of this 

 Devonian flora, a flora, be it remembered, which is characteristic 

 of a special physical environment : there may have been other 

 contemporary plant-associations, with very different habitats. The 

 three genera of vascular plants discovered in the Bhynie chert are 

 JRliynia, Hornea, and Asteroxylon. Uliynia, represented by two 

 species, was a leafless and rootless plant reaching a height of about 



