226 GEOLOGY. 



There were few, if auy flowers in all this vegetation, but 

 " what was wanting in blossom," says Page, " was more 

 than compensated for by the profusion of light, symmet- 

 rical, feathery fronds, and by the tall, pillar-like stems 

 which rose, each one boldly carved with its own pecul- 

 iar pattern. The trunks of a modern forest are rough 

 and gnarled; those of the period now under review 

 sprang up like the sculptured shafts of a medieval tem- 

 ple, graceful in proportion, and rich in ornament through 

 the endless repetition of flutings, spirals, zigzags, loz- 

 enges, ovals, and other geometrical designs these de- 

 signs being the persistent leaf-scars of a vegetation sim- 

 pler in structure and more 

 primitive in plan." An exam- 

 ple of the leaf-scars of which 

 he speaks is represented in 

 Fig. 130, the scars left by the 

 fallen leaves being seen at a, 

 while at b is the surface of 

 the wood brought to view by 

 the removal of the carbon- 

 Fig - m ized bark. You observe the 



regularity with which these scars are arranged. The 

 modes of this regularity differ in different plants, thus 

 affording a rich variety. 



326. Causes of the Rank Carboniferous Vegetation. 

 In order to understand how the rank vegetation of that 

 age was produced, you must recur to what I said of the 

 chemistry of the atmosphere in Part II. You there 

 learned that from the carbonic acid gas which is sup- 

 plied to the air from the lungs of animals, from fires, and 

 from various chemical decompositions, the leaves gather 

 in the most of the carbon which is incorporated in the 

 plants in their growth. Now it is supposed that there 

 was much more carbonic acid in the atmosphere up to 

 the beginning of the coal-making age than there was at 

 its close. Some estimate it as having been six times as 



