Officinal. Getraria, Lond. Lichen Islandicus, Edin. Cetra-ria Islandica, planta, Bub. Iceland Liverwort.

Syn. Lichen d'Islande (F.), Islandisches moos (G ), Yslandsch moos (Dutch), Islands moos (Dan.), Islands mossa (Swed.), Liqnen Islandico (S.), Musgo Islandico (Fort.), Lichene Islandico (I.).

This species of Lichen, or Cetraria, as it is now termed, is an indigenous perennial. It is very abundantly found in Iceland, and in the north of Germany; and is more or less common on all the heaths and mountains of the north of Europe.2 It grows to the height of two or three inches only, and has a rugged, bushy aspect. The frond is dry, coriaceous, lobed, and laciniated, the lobes being subdivided and notched, resembling in appearance a buck's horn; but concave above, and convex beneath: their surface is smooth, shining, and blistered; the margins beset with short, very minute, rigid, parallel hairs: and the colour of the whole is greenish yellow, or greyish brown.

This plant is used in Iceland and Lapland as an article of diet; being boiled in broth or milk, after being freed from its bitter by repeated maceration in water; or dried and made into bread. It has of late years been brought in considerable quantity to this country for medicinal purposes.

Qualities.-The dried lichen differs very little in its appearance from the recent plant. It is inodorous, and has a bitter mucilaginous taste; is neither very tough nor very brittle, but is not easily pulverized. When macerated in water it absorbs more than its own weight of the fluid, and the blisters appear like little white, opaque glands, while the other parts of the plant are diaphanous. If the water employed in the maceration be warm, it acquires a strong bitter taste, very similar to that of an infusion of quassia. The macerated lichen boiled in water affords a yellow-coloured inodorous decoction, which thickens as it cools, and becomes a tremulous jelly resembling starch, but without any viscidity. After some time this jelly cracks, separates from the watery part, and dries into semi-transparent masses, which are not soluble in cold water, but soluble in boiling water; and from which it is again precipitated by infusion of galls. According to the analysis of Proust, 100 parts of lichen afford 64 parts of a substance insoluble in hot water, somewhat resembling vegetable gluten; 33 parts of a matter soluble in hot water, resembling starch: and three parts of a bitter extractive principle.1 But according to Dr. John, the components are, inuline 8, mucilage 40, extractive 10, green resin 1.5, saline matter 4.5, and insoluble matter 375 parts.

A more recent examination has been made by Berzelius, who procured three per cent, of bitter principle, which in its pure state is of a clear yellow colour, pulverulent, light, and intensely bitter. It is more soluble in alcohol than in water. The fecula of the lichen does not strike a blue colour with tincture of iodine: thence it is correctly supposed to be inuline.

1 The Dublin College refers the plant to Cetraria Islandica.

2 It grows abundantly in the Asturias.-Journ. de Physique, 1806.

Medical properties and uses.-Iceland liverwort is tonic and demulcent. From some remarks of Linnaeus, made in 1737 in the Flora Lapponica, it would appear that the Danish physicians had long before that time employed this lichen, and found it efficacious in haemoptysis, and pulmonary complaints; but it did not excite the attention of even the continental physicians till after Scopoli's observations on it, in 1769, were published; and very few years have passed since it was known as a remedy in this country. Its virtues for the cure of phthisis have been very highly extolled; but experience has not altogether confirmed the truth of the praises which have been lavished on it.2 Its supposed specific effects are said to depend on the combination of its tonic, bitter, and its demulcent properties. As a demulcent it is certainly superior to the mucilages; and, owing to the bitter principle it contains, its decoction affords all the good effects that can be obtained from the other demulcents, and the mucilages, without loading the stomach.

It allays the tickling cough, and relieves the oppressed breathing; involves the acrid matters contained in the stomach and bowels which often induce diarrhoea; and renders more bland the whole mass of animal fluids, so as to mitigate hectic fever, while, at the same time, it tends to invigorate the digestive organs. Still, however, its efficacy in phthisis is very circumscribed; but the circumstances above enumerated ought not to be overlooked, nor the Iceland lichen regarded, as it often is, as a demulcent not more worthy of notice than the other articles of the same class. Besides phthisis, it has been also found useful in debilities after acute diseases, and in emaciations, particularly those arising from the great discharge of ulcers; in diarrhoeas, dysentery, and hooping-cough.

1 Journ. de Physique, 1806.

2 It still possesses a high reputation as a remedy for phthisis by the natives of Iceland.-Mackenzie's Travels, 4to. Appendix, p. 411.

It is generally exhibited in the form of decoction (see Pre-parations and Compositions); but as the bitter proves hurtful where the lungs or other viscera are actively inflamed, that ingredient must be therefore partly separated. This is effected by cutting or pounding the lichen, macerating it in several waters, and then, after boiling it for ten minutes, and decanting off the water, boiling it to the form of a mucilage in a fresh portion of water.

Officinal preparations.-Decoctum Cetrariae, L. Decoctum Li-chenis Islandici, D.