LICHENS: THEIR USES. 21 



dantly in the Canary, Cape de Verd, and other 

 islands, and scantily in Guernsey and the isle of 

 Portland. It is the ' Orchella lichen/* from which 

 a colour is obtained which, when evaporated to 

 powder, is the deep-red substance sold in our shops 

 as cudbear. Prepared orchella is, however, usually 

 known by the name of archil, and is of a rich 

 crimson colour, bordering on violet. It is used 

 more frequently to give a rich bloom to other 

 colours than alone, and it is interesting to find 

 that a similar practice was adopted in the time of 

 Pliny, who, speaking of this moss as growing on 

 the rocks of Candia and Crete, mentions that the 

 dyers employed it to give the first tint or ground 

 colour to stuffs which were intended to be of a 

 costly purple. Several other lichens yield dyeing- 

 material, but the Eocella is the most important. 

 It is however fugitive and evanescent in its cha- 

 racter, as may be seen by the changes in litmus 

 paper, which is dyed with this substance." 



" Why does Henry always look out for lichens 

 that have little cups or shields upon them ?" said 

 Robert. 



"Because these shields contain the spores, or 



* Jtocella tincioria. 



