biuret (biuret)

[ bivalence (bi'vā- or biv'a-lens), n. In chem., a valence or saturating power which is double that of the hydrogen atom. bivalency (bi'vaor biv'a-len-si), n. Same as bivalence. bivalent (bi'vā- or biv'a-lent), a. [L. bi-, two-, + valen ( t- )s, having power. Cf. equivalent.] In chem., applied to an element an atom of which can replace two atoms of hydrogen or other univalent element, or to a radical which has the same valence as a bivalent atom. Thus, calcium in its chlorid, CaCl2, replaces two atoms of hydrogen in hydrochloric acid, HCl; the bivalent radical methylen, CH2, in its chlorid, CH2Cl2, shows the same valence. bivalve (bī'valv), a. and n. [F. bivalve, II. n. 1†. pl. Folding doors.-2. In zoöl ., a headle lamellibranch mollusk whose shell has two hinged valves, which are opened and shut IMG:content-2122.png:[blocks in formation] Bivalve Shell of Cytherea chione. A, right valve; B, left valve; C, dorsal margin; D, ventral margin; E, anterior side or front margin; F, posterior side or hinder margin; G, umbo; H, hinge and hinge-teeth; 0, cardinal tooth; x, x, lateral teeth; 7, ligament, ligament pit or groove; F, lunule; K, anterior muscular impre ion; L, posterior muscular impre ion; M, pallial impre ion; N, abdominal impre ion; 0, pallial sinus. valve. See equilateral. IMG:content-2123.png:[blocks in formation] rare cases, as Pholas, there are also acce ory valves besides the two principal ones. See cut under acce ory. Familiar examples are the oyster, scallop, mu el, etc. These belong to the a siphonate division of bi valves; the clam, cob, cockle, razor-shell, and many others are siphonate. The Cf. piddock belongs to the genus Pholas. The ship-worm, Teredo, is also technically a bivalve. See lamellibranch. 3. In bot., a pericarp in which the seed-case opens or splits into two parts. — Equilateral bib i valved (bi'valvd), a. [ bivalvous (bi-val'vus), a. IMG:content-2124.png:[ocr errors][merged small] Same as bivalved . bivalvular (bi-val'vū-lär), a. [ bivalve , after valvular .] Having two valves: said especially of the shells of certain mollusks and of the seed-ve els of certain plants. See bivalve. bivascular (bi-vas kū-lär), a. [ + venter, belly.] A muscle of the back of the neck, so called from having two fleshy bellies, with an intervening tendinous portion. It is commonly distinguished from other biventral or digastric muscles as the biventer cervicis. It occurs in man, various mammals, birds, etc. Also called big aster. biventral (bi-ven'tral), a. [