429. Manna.
The concrete saccharine exudation from Frax'inus or'nus Linné.
BOTANICAL CHARACTERISTICS.—A tree about 25 feet high. Leaves pinnate, leaflets 7 to 9, serrate. Panicles dense; calyx 4-cleft; corolla white, divided to the base into linear segments.
SOURCE.—The tree yielding the manna is a native of Sicily, Calabria, and Apulia. The juice exudes spontaneously, or its flow is hastened by incision. Although this is the only manna officially recognized, saccharine substances known as mannas are yielded by many other trees and plants, and are obtained from the cocoons of some insects. The manna of Scripture was doubtless a lichen which grows extensively in the Sahara and Western Asia, and which occasionally falls like rain over the adjacent country.
DESCRIPTION OF DRUG.—In stalactiform pieces from 1 to 6 inches long, or irregular fragments, yellowish or brownish-white, internally white and porous; very friable. Manna in tears is a pure kind, but manna in flakes is chiefly valued and mostly met with. Manna in sorts, minute tears, internally crystalline, and fat manna, brownish viscid, non-crystalline masses, arc also met with. Odor honey-like; taste sweetish, afterward nauseous. Soluble in water and alcohol. When long kept, manna darkens and deliquesces into a liquid.
OTHER MANNAS.—Manna occurs in irregular masses, consisting of brittle and soft resin-like fragments from yellowish-white to yellowish-gray color. The quantity of the yellowish-white fragments should not be less than 40 per cent. of whole. The varieties of manna generally distinguished in our commerce are large flake, small flake and sorts.
INFERIORITY.—Inferior manna may have a greenish color due to froxin, a fluorescent glucoside resembling Tsculin. A new variety of manna from Rhodesia, probably derived from Gymnosporia deflexa is on the market.
ADMINISTRATION.—May be given to very young children as a gentle laxative. Given by dissolving in milk. When administered to adults it is combined with senna, rhubarb, and more energetic laxatives.
CONSTITUENTS.—Chiefly mannite (75 per cent.), a sweet principle which separates out from the boiling alcoholic solution in crystals, also sugar, dextrin, mucilage, and a nauseous principle, to which its laxative action is doubtless due.
ACTION AND USES.—Gentle laxative, usually given in combination with other purgatives. Dose: ½ to 2 oz. (15 to 60 Gm.).
PREPARATION.—Infusum Sennae Compositum. Dose: 1 to 4 fl. oz. (30 to 120 Mils).
