Chondrus crispus, Stackhouse (Sphærococcus crispus, Agardh; Fucus crispus, Linné), and Gigartina mamillosa, J. Agardh (Sphærococcus mamillosus, Agardh; Mastocarpus mamillosus, Kützing; Chondrus mamillosus, Greville).
Class: Algæ.
Common Names: Irish moss, Carragheen, Caragahen, Carragaheen.
Botanical Source.—Chondrus crispus, Stackhouse. Irish moss, sometimes called carrageen, has a root-disk, throwing up tufts of many flat, nerveless, slender, cartilaginous fronds, from 2 to 12 inches in height, subcylindrical at the base, but immediately becoming flat, generally dilating from the base upward, until they become 3 or 4 lines wide, then dividing repeatedly and dichotomously, each division spreading and becoming narrower than the preceding one, and taking place at shorter and shorter intervals; the summits are bifid, the segments linear, wedge-shaped, varying greatly in length, rounded or acute, straight or curved, often twisted in such a manner as to give the curled appearance denoted in the specific name. The fructification is roundish or roundish-oval, and subhemispherical. The capsules are imbedded in the disk of the frond, prominent on one side, producing a concavity on the other, containing a mass of minute, roundish, red seeds. The substance is cartilaginous, in some varieties approaching to horny, flexible, and tough. The color is a deep purple-brown, often tinged with a purplish-red, paler at the summit, becoming greenish, and at length white in decay (L).
Gigartina mamillosa, J. Agardh. This plant differs chiefly from the preceding in the situation of its cystocarps (sporocarps or capsules), which, instead of being slightly raised and near the extremities of the segments, as in the foregoing species, are borne on short, tuberculated projections or stalks, scattered over the channeled thallus.
History.—These are very common European plants found along the seacoasts, especially along the west shores of Ireland, where quantities of it are gathered. They also grow on the Atlantic shores of this country. Large quantities of Irish moss are annually collected on the Massachusetts coast. It is found attached by its disk to the rocks along the sea, where it is collected in the spring-time, washed, and spread on the sands some distance from the shore-line, and allowed to lie in the sun until it becomes well bleached and of translucent, horny texture, when it is ready for market. It was introduced into medicine in 1831, by Todhunter, of Dublin. Carrageen (more properly carraigeen) signifies, in Irish, “moss of the rock” (Pharmacographia). It is used to some extent in the arts, as sizing for paper and cotton fabrics in calico printing, for filling mattresses, and in this country in making beer. Cattle are sometimes fed on it (Pharmacographia). When fresh its color is somewhat purple, but when cleansed, and dry, as met with in commerce, it is in long crispy pieces, yellowish, or dirty-white, nearly inodorous, and of a mucilaginous taste. It swells up in warm water, and almost entirely dissolves in boiling water, forming a jelly when cold.
Description.—“Yellowish or white, horny, translucent; many-times forked; when softened in water, cartilaginous; shape of the segments varying from wedge-shaped to linear; at the apex emarginate or 2-lobed. It has a slight sea-weed odor, and a mucilaginous, somewhat saline taste. One part of it boiled for 10 minutes with 30 parts of water yields a solution which gelatinizes on cooling, and is not colored blue by iodine T.S.”—(U. S. P.).
Chemical Composition.—Irish moss contains oxalate of calcium, compounds of sulphur, iodine, chlorine, bromine, potassium, magnesium, and sodium, and a large portion (as high as 80 per cent), of pectin matter. Flückiger, however, failed to find sulphur in the mucilage. Though starch is not present, Flückiger has shown that if thin pieces of the moss be treated for one day with solution of caustic potash in alcohol, the cell-contents (not cell-walls), react with a dark-blue coloration with the iodide of potassium iodine solution (Pharmacographia). Pereira considered the pectin to be a peculiar modification of mucilage, and has called it carrageenin. Carrageenin may be known from gum by its watery solution not affording a precipitate on the addition of alcohol; from starch by its not assuming a blue color with tincture of iodine; from animal jelly, by tannin causing no precipitate; and from pectin by acetate of lead not throwing down anything, though mucic acid is formed by the action of nitric acid.
Action, Medical Uses, and Dosage.—A decoction of Irish moss, with water or milk, is very nutritious, and may be used as a demulcent in chronic affections of the air passages, chronic diarrhœa and dysentery, scrofula, rickets, enlarged mesenteric glands, irritation of the bladder and kidneys, etc. As a culinary article it may be employed in the preparation of jellies, white soup, blanc mange, etc. The decoction is prepared as follows: Macerate ½ ounce of carrageen in cold or warm water, during 10 minutes; then boil in 3 pints of water, or milk if stronger nourishment is desired, for a quarter of an hour. Strain through linen. Sugar, lemon-juice, tincture of orange-peel, essence of lemon, or other aromatics, as cinnamon or nutmeg, may be employed as flavoring ingredients.
Related Species and Drugs.—Other species of algæ are said to be collected with the true Irish moss, the Gigartina acicularis, Lamouroux, having small, cylindrical segments, and having been sold in France as carragheen (Dragendorff). Another species resembling carragheen is the Gigartina pistillata, Lamouroux.