LICHENS. 7 



with tree-moss, from which a gum is extracted which 

 answers the same purpose as that known by the name of 

 Senegal. The ragged mealy lichen differs somewhat in its 

 growth and hue, and is readily distinguished by numerous 

 irregular cracks on the sides and edges of its broad seg- 

 ments. A mucilage is extracted from them, which in drying 

 becomes transparent, and possesses the essential properties 

 of gum-arabic. Further up the glen a group of aged trees, 

 growing among ferns, are covered in like manner with long 

 tufts of the ragged lichen, which differs according to its place 

 of growth such as affect the willow being nearly as soft as 

 silk, while such as pertain to the hawthorn assume a hoary 

 appearance, but, wherever growing, imbued with the sin- 

 gular property of retaining odours, and becoming in con- 

 sequence the basis of many perfumed powders. 



Such are a few among our tribes indigenous to Britain, 

 and of which the seeds, sown by autumn winds, took root 

 in the interstices of the old stone, or found a resting-place 

 in this solitary ravine. Mark well our dissimilar localities 



