These lichens, more especially Letharia vulpina, have been used by Northern peoples to poison wolves. Dead carcasses are stuffed with a mixture of lichen and powdered glass and exposed in the haunts of wolves in time of frost. Henneguy[1285], who insists on the non-poisonous character of all lichens, asserts that the broken glass is the fatal ingredient in the mixture, but Kobert[1286], who has proved the poisonous nature of vulpinic acid, says that the wounds caused by the glass render the internal organs extremely sensitive to the action of the lichen.
Kobert, Neubert[1287] and others have recorded the results of experiments on living animals with these poisons. They find that Letharia vulpina either powdered or in solution has an exciting effect on the mucous membrane. Elementary organisms treated with a solution of the lichen succumbed more quickly than in a solution of the acid as a salt. Kobert concluded that vulpinic acid is a poison of protoplasm.
He further tested the effect of the poison on both cold- and warm-blooded animals. Administered as a sodium salt, 4 mg. proved fatal to frogs. The effect on warm-blooded animals was similar. A sodium salt, whether swallowed or administered as subcutaneous or intravenous injections, was poisonous. Cats were the most sensitive—hedgehogs the least—of all the animals that were subjected to the experiments. Volkard’s[1288] synthetic preparation of vulpinic acid gave the same results as the solution directly extracted from the lichens.
D. Lichens used in Tanning, Brewing and Distilling
The astringent property in Cetraria islandica and in Lobaria pulmonaria has been made use of in tanning leather. The latter lichen grows commonly on oak and could hardly be gathered in sufficient quantity to be of commercial importance. Like many other lichens it develops very slowly. Lobaria pulmonaria has also been used to replace hops in the brewing of beer. Gmelin[1289] in his journey through Siberia visited a monastery at Ussolka where the monks employed it for this purpose. The beer tasted exactly like that made with hops, but was more intoxicating. The lichen in that country grew on pine-trees.
Lichens have in more modern times been used in the preparation of alcohol. The process of manufacture was discovered by Roy of Tonnerre, early in the nineteenth century, and was described by Léorier[1290]. It was further improved by Stenberg[1291], a Professor of Chemistry in Stockholm. Roy had worked with Physcia ciliaris, Ramalina fraxinea, R. fastigiata, R. farinacea and Usnea florida, but Stenberg and distillers after his time[1292] made more use of Cladonia rangiferina ([Fig. 127]), Cetraria islandica ([Fig. 128]) and Alectoria jubata.
By treatment with weak sulphuric or nitric acid the lichenin of the thallus is transformed into glucose which on fermentation forms alcohol. Stenberg found that 68 per cent. of the weight in Cladonia rangiferina was a “sugar” from which a good brandy could be prepared: a kilogramme of the lichens furnished half a litre of alcohol. The Professor followed up his researches by establishing a distillery near Stockholm. His papers contain full instructions as to collecting and preparing the plants. Henneguy[1293], writing in 1883, stated that the fabrication of alcohol from lichens was then a large and increasing industry in Sweden. The whole industry seems, however, to have fallen into disuse very soon: Wainio[1294], quoting Hellbom[1295], states that the various distilleries were already closed in 1884, because of the exhaustion of the lichen in the neighbourhood, and the impossibility of obtaining sufficient supplies of such slow-growing plants.
E. Dyeing Properties of Lichens
a. Lichens as Dye-plants. Knowledge as to the dyeing properties of lichens dates back to a remote antiquity. It has been generally accepted that lichen-colours are indicated by the prophet Ezekiel in his denunciation of Tyre: “blue and purple from the Isles of Elishah was that which covered thee.” Theophrastus describes certain plants as growing in Crete, and being used to dye wool, etc., and Pliny in his Phycos Thalassion is also understood as referring to the lichen Roccella, “with crisp leaves, used in Crete for dyeing garments.”