CHAPTER X. 



INVOLUTION. 



MAISTT years ago, in the clay which in every part of 

 the world is found underlying beds of coal, a peculiar 

 fossil was discovered and named by science Stigmaria. 

 It occurred in great abundance and in many countries, 

 and from the strange way in which it ramified 

 through the clay it was supposed to be some extinct 

 variety of a gigantic water-weed. In the coal itself 

 another fossil was discovered, almost as abundant but 

 far more beautiful, and from the exquisite carving 

 which ornamented its fluted stem it received the name 

 of Sigillaria. One day a Canadian geologist, studying 

 Sigillaria in the field, made a new discovery. Finding 

 the trunk of a Sigillaria standing erect in a bed of 

 coal, he traced the column downwards to the clay 

 beneath. To his surprise he found it ended in Stig- 

 maria. This branching fossil in the clay was no 

 longer a water-weed. It was the root of which Sigil 

 laria was the stem, and the clay was the soil in which 

 the great coal-plant gre\v. 



Through many chapters, often in the dark, every- 

 where hampered by the clay, we have been working 

 among roots. Of what are they the roots ? To what 



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