566

elements of materia medica.

drachms, mixed with honey or sugar; but the more usual mode of exhi-bition is in the form of decoction, prepared by boiling from four to sixdrachms of Corsican moss in a pint of water; of this the dose is a wine-glassful, three times daily.

1. Alg<B Esculents.— Esculent Sea Weeds.Fig. 70.

Esculent Sea Weeds.

a, Rhodomenia palmata (or dulse). d, Iridsea edulis.

b, Rhodomenia ciliata. e, Alaria esculenta.

c, Laminaria saccharina. f, Ulva latissima.

Several species of the inarticulated Algre are occasionally employed, in some parts ofthe British islands, as articles of food, or as condimentary substances. Taken in thisway, they might perhaps prove serviceable in scrofulous affections and glandular en-largements. Besides the species above depicted, the following have also been used :Laminaria digitata (or Tangle, p. 110, fig. 36, d), Porphyra laciniata and vulgaris (com-monly called Laver), Laurentia pinnatifida (Pepper-dulse), Sec. (For further details,consult Dr. Greville’s Algee Britannicw, xix.; Loudon’s Encyclopedia of Gardening, 2ded. p. 886; and Plenck ’s Bromatdlogia, pp. 171-3).

2. Sea Weeds from which Kelp and Iodine are procured.

These have been before referred to (vide pp. 110 and 323). To the informationalready given, I have only to add the following table drawn up by Mr. Whitelaw, amanufacturer in Glasgow , from his own experiments, showing the proportion of iodin®contained^in some of the most common Algue on our sea coasts (Thomson’s Chemistry of

Organic Bodies, 946).

Ratios of Iodine. Ratios of

Laminaria digitata .... 100 Fucus serratus.20

Laminaria bulbosa .... 65 Fucus nodosus.15

Laminaria saccharina ... 35

The quantities of chloride of potassium were nearly in the same ratio.

Order 2. Liche'nes, Juss. —The Lichen Tribe.

Lichen Ack.k, Lind.

Essential Character. —Perennial plants, often spreading over the surface of the ea r ^|or rocks, or trees, in dry places, in the form of a lobed and foliaceous, or hardcrustaceous or leprous substance, called a thallus, crust, or frond (receptaculum c tmune). This thallus is formed of a cortical and medullary layer, of which the fo f . gSis simply cellular, the latter both cellular and filamentous. In the crustaceous sP e ®the cortical and medullary layers differ chiefly in texture, and in the former “f ,] acoloured, in the latter colourless; but in the fruticulose or foliaceous species, the raea