1841.] On Lichens. 891 



stitute the Tripe de Roche of the Canadians, and with G. prohoscidea, G. 

 villea, and a few other American species, Capt. Sir J. Franklin and his 

 brave companions were supported in Arctic America during a season 

 of want, such as happily few human beings have been subjected to. They 

 are, however, bitter and nauseous, and can only be employed in the 

 total absence of every other salutary food. — English Flora, vol. v. p. 217. 



Note. — Berzelius has proposed removing the bitter principle of these 

 Lichens, 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 Cetraria, and imparts 

 tonic properties to several of the species, as to Borrera furfuracece and 

 others, which have been used for the same purpose as Cetraria Islandica^ 

 and some have been employed as a substitute for hops in the brewing of 

 beer. — Royle's Illustrations, vol. i. p. 438. 



Gyrophora Cylindrica, Ach. 



Is used in Ireland occasionally as food, and more frequently for dye- 

 ing woollen cloth of a brownish green colour. — English Flora, vol. y. p. 218. 



Cetraria Islandica, Ach. 



Although this plant is abundant in certain districts of Scotland, it has 

 never with us been collected as an article of commerce. A considerable 

 proportion of what comes to our shops, where it is in great request as a 

 medicine in coughs, consumptions, &c. is procured from Norway and 

 Ireland. Immense quantities are gathered in the latter country, not only 

 for sale, but for their own use as an article of common food ; the bitter 

 and purgative quality being extracted by steeping in water. The Lichen 

 is then dried, reduced to powder, and made into a cake, or boiled and eaten 

 with milk, and eaten with thankfulness too by the poor natives, who con- 

 fess " that a bountiful Providence send them bread out of the very stones." 

 — English Flora, vol, v. p. 271. 



Note. — The starchy substance which renders the C. Islandica nutritive 

 and demulcent, is called Lichenin. — Moyle's Illustrations, vol, i» p. 438. 



Rocella tinctoria, DeCand. 



This interesting Lichen is the famous Archill or Orchill ; Orseille of the 

 French, which yields the most valuable dye of all this tribe. Its several 

 names are derived from a Florentine family of the Oricellarii, Riccellarii, or 

 Riccellai, one of whom in the year 1300, carried on a considerable trade in 

 the Levant, and returning with great wealth to Florence, first made known in 

 Europe, the art of dyeing with this plant. Far more abundantly than with 



