Gelidium corneum (Hudson) lamouroux, and other species, also closely related agae. The dried extracted mucilaginous substance, with not more than 1 p.c. foreign organic matter, yielding not than 1 p.c. acid-insolluble ash and 16 p.c. moisture.

Habitat. Japan, China, Malaysia, Ceylon; Atlantic Ocean, United States.

Syn. Agar-agar, Jelly Plant, Corsican (Worm) Moss, Crow-silk, Japanese (Chinese, Bengal, Ceylon) Isinglass, Vegetable Gelatin, Gelosine; Fr Mousse de Chine; Ger. Wurmmoss, Wurmtang.

Ge-lid'i-um. L. See etymology, above of Gelidiaceae.

Cor'ne-um. L. Fr. Corneus, hard, horny -- i.e., the tough fronds.

A'gar-A'gar -- i.e., fr. Malay agar-agar, Eastern name of Ceylon Moss or Bengal Isinglass.

Plant

Very similar to Chondrus crispus and Gigartina mamillosa, Irish Moss, but in reproduction the carpogonium gives rise to one or more elongated branched ooblastima filaments which fuse with one or more auxiliary cells, the sporangia being produced from the ooblastima filaments -- not directly from the auxiliary cell (cells). AGAR occurs usually in bundles, 30-60 Cm. (1-2 degrees) long, consisting of thin, translucent, membranous, agglutinated pieces, 4-10 Mm. (1/6 - 2/5') broad, yellowish-brownish-white, tough (damp), brittle (dry), insoluble in water, slowly soluble in hot water; solution in hot water (1 in 100 -- stiff jelly upon cooling; odor slight; taste mucilaginous. Powder, pale buff -- in chloral hydrate T.S., fragments transparent, granular, striated, angular, occasionally frustules of diatoms. Tests: 1. -- With iodine T.S., some fragments -- bluish-black, with some areas -- bright red. 2.--Aqueous-solution (1 in 100), made by boiling, upon cooling, + tannic acid T.S. -- no pricipitate (abs. Of gelatin), + iodine T.S. -- not blue (abs. Of starach). Impurities: Shells, incrusting Bryozoa, spicules, sand, gelatin, starch. Solvent: hot water. Dose, 3j-2 (4-8 Gm.).

Commercial

Seaweeds, collected by hand and rakes, May-August, are spread upon beach to dry and bleach in the sun, then pounded by hand or passed through a concrete mortar-and-pestle battery (to remove adhering shells, frustules, spicules, sand, etc.), then alternately washed and sun-dried for several days until thoroughly bleached and cleansed -- a process sometimes hastened by bleaching chemicals. It is now boiled, 3-5 hours, with water (1 in 50) in an iron kettle (to extract the gelose in soluble form), filtered through (1) coarse cloths and (2) squeezed through linen bags in a press (to separate from insoluble matter), and the filtered jelly poured into wooden trays 2 degrees long, 1degree wide, 3' deep, to cool and solidify into hard jelly (Japanese "tokoroten"), which is cut by sharp knives into blocks, 1 degree long, 2' square, and pressed through coarse wire grating that divides them into bundles of slender straws. In this condition, the "tokoroten" is subjected to low temperature, -- 5- --15 degrees C. (23-5 degrees F.), until sticks are frozen solid (to allow water to crystallize out), and then melted (to permit substances soluble in cold water to drain off in solution), thereby leaving pure gelose. Repeated freezing, thawing, and drying in the sun (open air) yields a pure agar insoluble in cold water. Sticks, before thoroughly dry, may be put through a forcing machine that flattens each fine strip into a transparent sheet, which, after drying in the sun, are tied into bundles, 2 - 3 pounds; it is also prepared in sheets 8-12' long, 1-1 1/2' wide, and in rectangular blocks, 8' long, 1' square. Our importation, 1920, was 240 tons, valued at $500,000, which suggests our using G. Cartilagin'eum and G. Aman'sii, California coast, that yield a dry gelatin 28-30 p.c. of which a 2 p.c. solution makes a hard, elastic jelly, the equal of agar, that remains hard at 58 degrees C. (137 degrees F.) and does not begin to liquefy until 76 degrees C. (170 degrees F.).

Constituents

Gelose (gel'(atin) + ose), amorphous gelatin-like carbohydrate 60-70 p.c., moisture 23 p.c., mineral salts, ash 4 p.c., gelose heated with strong nitric acid yields mucic and oxalic acids; dissolved in acidulated water with heat -- does not gelatinize on cooling.

Properties And Uses

Demulcent, nutrient, aperient, emulsifier. In the United States chiefly in hospitals and bacteriological laboratories as a base for culture media, being superior to any substitute as it remains solid (other jellies useless -- melting under requisite conditions), with a smooth, firm surface at the higher temperature required for cultivating certain species of bacteria. In chronic constipation (instead of mineral oil), the action depends on its property of absorbing and holding water, along with it becoming a lubricant and mild mechanical stimulant, unaffected by digestive enzymes of intestinal bacteria; action not violent, as ordinary cathartics, and leaves no harmful after-effects, being best when stools unduly dry. In Japan and China long esteemed as a food in making jellies and candy; thickening soups, ice cream, fruits, meats, fish, etc. It is a valuable dressing for wounds, and its emulsion for photographic plates is superior to that of ordinary gelatin. May be taken in granular powder, or emulsionized with mineral or other oils, or mixed with cereal, bread, biscuit, chocolate agar, etc. It is a poor substitute for sodium stearate in suppositories, as it absorbs only 70 p.c. of glycerin, and melts at higher than body temperature. Native "Kanten" and "Funori," from related algae, are used to impart gloss to textiles, silk, stiffening linen (starch), decorating china, plastering walls, sizing, glue, etc. Dose, 3j-4 (4-15 Gm.).