in physiology, the rainbow. The word is Greek, ἰρις, supposed by some to be derived from ἰρισμένος "I speak, I tell;" as being a meteor that is supposed to foretell, or rather to declare rain. See Rainbow.

Lunar Iris, or Moon-rainbow. See Rainbow (Lunar).

anatomy, a striped variegated circle round the pupil of the eye, formed of a duplicature of the uvea. See Anatomy, p. 767.

Iris is also applied to those changeable colours which sometimes appear in the glasses of telescopes, microscopes, &c., so called from their similarity to a rainbow. The same appellation is also given to that coloured spectrum, which a triangular prismatic glass will project on a wall, when placed at a due angle in the sun-beams.

Flower de Luce, or Flag-flower, &c., in botany: A genus of the monogynia order, belonging to the triandra clas of plants; and in the natural method ranking under the fifth order, Enfatae. The corolla is divided into six parts; the petals alternately reflexed; the filigmate resembling petals.

There are 44 species, all herbaceous flowering perennials, both of the fibrous, tuberous, and bulbous rooted kind, producing thick annual stalks from 3 or 4 inches to a yard high, terminated by large hexapetalous flowers, having three of the petals reflexed quite back and three erect; most of which are very ornamental, appearing in May, June, and July.

Culture. All the species are easily propagated by offsets from the roots, which should be planted in September, October, or November, though almost any time from September to March will do. They may also be raised from seed, which is the best method for procuring varieties. It is to be sown in autumn, soon after it ripens, in a bed or border of common earth, and raked in. The plants will rise in the spring, and are to be transplanted next autumn.

Properties. The roots of the Florentine white iris, when dry, are supposed to have a pectoral virtue. They have an agreeable smell, resembling that of violets; and hence are used in perfumes, and in flavouring of liquors. When recent, they have a bitter, acid, nauseous taste; and when taken into the body, prove strongly cathartic; on which account they have been recommended in dropsies, in the dose of three or four scruples. —The juice of the species called bastard acorus, or yellow flag-flower, is also very acid, and hath been found to produce plentiful evacuations from the bowels when other means had failed. For this purpose, it may be given in doses of 80 drops every hour or two; but the degree of its acrimony is so uncertain, that it can hardly ever come into general use. The fresh roots have been mixed with the food of swine bitten by a mad dog, and they escaped the disease, when others, bitten by the same dog, died raving mad. Goats eat the leaves when fresh; but cows, horses, and swine, refuse them. Cows will eat them when dry. The roots are used in the island of Jura for dying black.—The roots or bulbs of a species growing at the Cape, are roasted in the ashes and used as food by the natives: they are called oenkjes, and have nearly the same taste with potatoes. The Hottentots, with more reflection than generally falls to the share of savages, use the word oenkjes in the same sense in which Virgil used that of ariftles, that is, for reckoning of time; always beginning the new year whenever the oenkjes push out of the ground, and marking their age and other events by the number of times in which in a certain period this vegetable has made its appearance.—The Siberians cure the venereal disease by a decoction of the root of the Iris Sibirica, which acts by purging and vomiting. They keep the patient eight days in a stove, and place him in a bed of the leaves of the arctium lappa, or common burdock, which they frequently change till the cure is effected.

Iris-Stone. See Moon-Stone.