X. THE BARK. 175 



stems for after-examination, content, at present, with 

 the general idea of the bark of an outlaid tree as the suc- 

 cessive accumulation of the annual protecting film, rent 

 into ravines of slowly increasing depth, and coloured, 

 like the rock, whose stability it begins to emulate, with 

 the grey or gold cf clinging lichen and embroidering 

 moss. 



