THE CARBONIFEROUS AGE. 125 



their produce. If we approach one of these trees 

 closely, more especially a young specimen not yet 

 furrowed by age, we are amazed to observe the accu- 

 rate regularity and curious forms of the leaf-scars, 

 and the regular ribbing, so very different from that of 

 our ordinary forest trees. If we cut into its stem, we 

 are still further astonished at its singular structure. 

 Externally it has a firm and hard rind. Within this 

 is a great thickness of soft cellular inner bark, tra- 

 versed by large bundles of tough fibres. In the centre 

 is a core or axis of woody matter very slender in pro- 

 portion to the thickness of the trunk, and still further 

 reduced in strength by a large cellular pith. Thus a 

 great stem four or five feet in diameter is little else 

 than a mass of cellular tissue, altogether unfit to form a 

 mast or beam, but excellently adapted, when flattened 

 and carbonised, to blaze upon our winter hearth as 

 a flake of coal. The roots of these trees were perhaps 

 more singular than their stems ; spreading widely in 

 the soft soil by regular bifurcation, they ran out in 

 long snake-like cords, studded all over with thick 

 cylindrical rootlets, which spread from them in every 

 direction. They resembled in form, and probably in 

 function, those cable-like root-stocks of the pond-lilies 

 which run through the slime of lakes, but the struc- 

 ture of the rootlets was precisely that of those of some 

 modern Cycads. It was long before these singular 

 roots were known to belong to a tree. They were 

 supposed to be the branches of some creeping aquatic 

 plant, and botanists objected to the idea of their being 



