INTRODUCTION 



turies ago, and Lime trees near Friburg have existed as long. Oaks, too, are 

 long-lived, and several in England have probably stood for 800 to 1500 years. 

 Space will not permit ns to pursue the subject further, but among others of 

 the longest-lived may be mentioned the Cypress, Larch, and Elm, whilst the 

 Wellingtonias and other giants of Western America carry us back in ima- 

 gination beyond the dawn of history. 



NATURES LABORATORY AND COAL 



We have spoken of the uses to which we put trees in the present age of 

 high civilisation. Rut what shall we say of those vast primeval forests which 

 m the course of bygone ages were annihilated, and in the hidden recesses of 

 Nature's laboratory transmuted into what we now know as coal? We can 

 scarcely imagine what would be the industrial conditions of to-day without 

 our seemingly inexhaustible supplies of this universal commodity, and the 

 innumerable by-products which man in his ingenuity extracts from it. Yet 

 what do we know of its origin ? Truly little indeed, and even that little 

 only through the patient toiling of the geologist and botanist, who have 

 combined to probe Nature's secrets and build up for us a feeble picture of 

 the luxuriant vegetation which clothed these antediluvian wilds in those days 

 which we call the Carboniferous Period. By patient research these workers 

 have pieced together the story, and they tell us that among the largest 

 forms which composed those forests were certain Lycopodiums or Club-mosses 

 known as Sigillaria± and Lepidodendra. 



The Sigillariae attained a height of 60 to 70 ft., the unbranched stem having 

 a number of longitudinal rows of diamond-shaped leaf-scars, and being some- 

 what hollow, so that where the trees have fallen and been subjected to great 

 compression, the fossil remains are simply the thickness of the double bark, 

 that is, the two opposite sides of the envelope which covered the trunk when 

 living. 



The Lepidodendra had much-branched stems, 100 ft. or more in length, 



also beautifully marked with scars, whilst the branches bore at their ex- 



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