438 ILLUSTRATIONS OF THE BOTANY OF [ Lichenes. 
with a species of Borrera, and from Ceylon varieties of Roccella fuciformis, with 
Ramalina fastigiata from the Sunderbund or Delta of the Ganges. 
Though obscure and apparently insignificant as plants, the Lichens yet serve some 
important purposes; some are useful as medicines, and others in the arts; several 
serve as food for herbivorous quadrupeds, as deer and antelopes, and a few for man 
himself. Those which have been employed as food, contain a starchy substance, called 
Lichenin, which renders them nutritive and demulcent: among these is Cetraria islandica, 
or Iceland Moss, after it has been steeped in water. The several species of Gyrophora, 
as G. proboscidea and G. vellea, though bitter and nauseous, constitute the tripe de Roche 
of the Canadians, which supported Sir John Franklin and his companions in Arctic 
America; they are found in cold rocky situations, especially on granite, in almost 
all parts of the world. G. cylindrica is occasionally used in Iceland as food. So, in 
Lapland, Alectoria jubata, according to Linneus, supplies the rein-deer with food in 
winter; as does Cladonia rangiferina, or rein-deer moss, which grows there in great 
abundance, and serves to pasture the vast herds of rein-deer, which constitute the sole 
wealth of the Laplanders. Many others might be edible, if it were not for the bitter 
principle which they contain along with the fecula. Berzelius has proposed removing 
this, by macerating them in a weak solution of carbonate of potass (one part to three 
hundred of water), and afterwards washing them in cold water. This bitter principle 
has been called Ceéraria, and imparts tonic properties to several of the species, as to 
Borrera furfuracea, and others which have been used for the same purposes, as Cetraria 
Islandica ; and some have been employed as a substitute for hops in the brewing of beer. 
Some of the Lichens are, however, more valuable for yielding a fine dye, than for 
any other purpose : this is developed, as is well known to practical men, by digesting 
the lichen, with the assistance of heat, in a weak solution of ammonia, (v. Visgor in 
Proc. of Com. Agr. R. As.Soc.) Of all the Lichens, Roccella tinctoria is by far the 
most valuable, being employed for making orchil or archil, and is for this purpose 
imported from the Canaries, Azores, and Cape-Verd Islands, as well as from Sicily: 
that obtained from the first is much the most valuable, selling even for £400 a ton. 
R. fuciformis, the other species of the genus, is more widely diffused, being found in 
Europe, Brazil, as well as in Ceylon, and the Peninsula of India, whence several 
specimens have been sent to the Royal Asiatic Society, but this is far inferior in quality, 
containing, indeed, hardly any colouring matter. Usnea barbata is described by Hum- 
boldt as being employed in South America for a similar purpose ; but some of the 
_ ¢rustaceous Lichens are also valuable, as Lecanora Parella, the Perelle of Auvergne 
and other parts of France, where it is extensively employed to produce a dye far 
_ Superior to that of another Lecanora, L. tartarea, the Cudbear, and equal to that of the 
: Roccella tinctoria ex Hooker. So also Parmelia savatilis and omphalodes are used in 
Scotland. Several other of the crustaceous Lichens are employed, though none 
yield so fine a colour as the Archil, or the Perelle; but as the colouring matter 
is not confined to a few only, it is more than probable that some of the Indian and 
Himalayan 
