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CHAPTER IV. 



GEOGRAPHICAL DISTRIBUTION. 



" 'Tis Nature's livery o'er the globe, 

 Where'er her wonders range." 



" The living stains, which Nature's hand alone, 

 Profuse of life, pours forth upon the stone ; 

 Eor 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, 

 Mix'd but not blended : each its name retains, 

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



We shall consider briefly the geographical diffusion of Li- 

 chens, both horizontally, that is, from the Equator to the 

 Poles, or in general over the earth's surface ; and vertically, 

 that is, from the base to the summits of mountains. The 



