44 THE AGE OF THE EARTH 



Note. — At the time when this address was delivered 

 I felt keenly the gap left in the argument by the absence 

 of any statement concerning the evolution of land-plants. 

 Since 1896 an immense amount of labour has been ex- 

 pended upon fossil floras, and startling conclusions as to 

 the affinities of certain groups have been placed on a 

 solid foundation. Now, after the lapse of ten years, it is 

 far more possible than it was in 1896 to compare safely 

 the evidence yielded by fossil plants with that of fossil 

 animals. Allowing for the important difference in the 

 length of the records — animals appearing in full force in 

 the Cambrian, plants only in the Devonian — the two lines 

 of evidence support precisely the same conclusion. 



Professor A. C. Seward, F.R.S., in his Presidential 

 Address to Section K (Botany) of the meeting of the 

 British Association at Southport, in 1903, took as his 

 subject Floras of the Past: their Composition and 

 Distribution. He speaks of the Devonian and Lower 

 Carboniferous plants as ' practically the oldest records of 

 plant-life', and states that they 'lead us away from the 

 present along converging lines of evolution to a remote 

 stage in the history of life': the distribution of their fossil 

 remains over the globe ' shows how widely some of the 

 plants had migrated from an unknown centre far back in 

 a still more remote age. We are, as yet, unable to 

 follow these Devonian plants to an earlier stage in their 

 evolution. We are left in amazement at their specialized 

 structure and extended geographical distribution, without 

 the means of perusing the opening chapters of their 

 history '. 1 



During the present year my friend Dr. D. H. Scott, 

 F.R.S., has published a valuable and comprehensive 

 memoir on The Present Position of Palaeozoic Botany, 2 

 setting forth the results of modern researches upon the 

 structure and evolution of fossil plants. 



Dr. Scott has most kindly provided me with the fol- 

 lowing concise summary of the history of plant evolution 

 as set forth in the fossil record at present known to us: — 



\ Report, 1903, p. 831. 

 Progressus Rei Bolanicae, Jena, 1906, pp. 139-217. 



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