ORDER VI. 

 LICHENES. 



" But ere you enter, yon bold Tower survey, 

 Tall and entire, and venerably grey, 

 For Time has soften'd what was harsh when new, 

 And now the stains are all of sober hue ; 

 The living stains, which Nature's hand alone, 

 Profuse of life, pours forth upon the stone; 

 For ever growing ; where the common eye 

 Can but the bare and rocky bed descry : 

 There Science loves to trace her tribes minute, 

 The juiceless foliage, and the tasteless fruit; 

 There she perceives them round the surface creep, 

 And while they meet, their due distinctions keep ; 

 kix'd but not blended ; each its name retains, 

 And these are Nature's ever-during stains." 



CRABBK. 



OBS. Lichens have no distinct roots, nor stem, nor leaves, pro- 

 perly so called ; and the fructification proceeds immediately from 

 the //OTIC/, a term by which is designated the entire body of every 

 individual plant. They grow on the ground, on rocks or on 

 trees, in thin leprous or warted crusts, or in lobed, leaf-like, ro- 

 saceous patches, or in shrubby or coralloid tufts. They are peren- 

 nial, coriacious, rarely somewhat gelatinous, variously coloured, 

 densely cellular, and, when dried, revive slowly on exposure to 

 moisture. They vegetate chiefly in the winter months, and, dry- 

 ing up during summer, become less conspicuous and of little 

 beauty. If a lichen be smartly stricken so as to rupture its 

 cells, the white internal substance or parenchyma becomes green. 



