Page:The American Cyclopædia (1879) Volume I.djvu/323

ALG.E 299 A convenient classification divides them into five orders, diatomacem, confervacece, fucacea, ceramiacew, and characea. The diatoms are Laurencia pinnatiflda. Laminarla digitata. microscopic bodies, having a spontaneous move- ment through the water in which they live, and silicious skeletons or frames, often of won- derful beauty, which accumulate in vast depos- its at the bottom of ponds. (See DIATOMACE^E.) The confervas are plants of simple cells or series of cells, commonly found in fresh water, but also in salt, growing with great rapidity, and forming a green, redj or violet scum on water, or stain on snow or moist stones. The red snow (protococcus nivalis) consists of a single cell, which subdivides into other cells forming new individuals, so that in a few hours a large extent of snow may be covered by this plant, which is only visible by its conglomera- tion. A similar plant often colors many square miles of the sea, and, according to some, has given the Red sea its name. Many fresh-water confervas appear in early spring, and when examined by the microscope are shown to be delicate threads composed of a single line of transparent cells of varied shapes, containing several forms of greenish nuclei ; these are the reproductive particles which are to form the spores. The star jelly (nostoc) springs up sud- denly after a rain as a greenish trembling jelly. Lavers (porphyra and ulva) are stewed and eaten in Europe, and the ulva compressa by the Hawaiian Islanders. Several confervas have been found growing in hot springs of an elevated temperature ; as at the geysers in Cal- ifornia, in a spring of a temperature of 120 F. (W. T. Brigham). The fucacece or seaweeds, when found in fresh water, much resemble confervas, but are distinguished from all other algae by the position of the spores in cells or receptacles sunk in the substance of the plant and opening at the surface by a small pore. The sea aprons (laminaria) have broad flat- tened fronds attached to a cylindrical stem, which holds the plant during growth fastened to rocky bottoms ; when torn off by waves, they are found floating, and sometimes of a length of several hundred feet. The lamina- ria saccharina is eaten in Japan, and the lami- naria digitata (called " tangle ") in Scotland. Bory de St. Vincent describes an alga of this family which attains a length of 25 or 30 feet, and the trunk is often as thick as a man's thigh. The sargassum or gulf weed forms im- mense beds in the Atlantic, covering 40,000 square miles. The bladder-weed (fucus vesi- culosus) is common on rocky coasts in temper- ate regions, and is easily recognized by its olive-green, strap-shaped, branching divisions, bearing at small intervals air bladders by means of which its free end floats in the rising tide. This fucus is used for manure, and also for the manufacture of kelp, and, with other algffi, as a source of iodine. A nutritious gela- tine is secreted by many of the fuci, and they are eaten by swine or other animals in times of scarcity, and even by man. Perhaps the most remarkable fucus is the hydrogastrum, described by Endlicher as a branching plant, imitating the root, stem, bud, and fruit of the higher plants, but all composed of a single branching cell. The fourth order, or cerami- acecB (rose tangles), comprises seaweeds of a rose or purplish color, seldom olive or violet ; the spores are grouped in fours or threes. The order is distinguished also for the amount of gelatine many of its species contain, rendering them most useful among seaweeds. Carra- geen moss (cTiondrus crispus) is used in place Chondrns crispus. Fucus resiculosns. of Iceland moss (a lichen, cetraria Islandica), and its bitter flavor is partly removed by steep- ing in fresh water for some time before boil- . ing ; it then takes the place of isinglass in pre- .paring jellies and blanc-mange. Dulse (iridcea edulis) is a thin purplish seaweed, which is eaten, as well as another alga, rhodomenia palmata, by the Scotch and Irish, who call it dillesk, and the Icelanders, who name it sugar seaweed ; within a few years it has become an article of food among the foreign popula- tion of Boston, and is sold in the streets. The East Indian swallows are said to construct the edible birds' nests from the gelidium, a genus of this order. The plocaria tenax (glceopeltis) furnishes so much good gelatine that it is an important article of commerce among the Chi- nese, many tons being annually imported at Canton for the preparation of glue and varnish for lanterns, windows, and paper umbrellas,