ORT 



294 



OS 



belonging to sand from arena, 

 sand), are parasitic upon different 

 species of Compositse, as Centaury, 

 and Milfoil : 0. major, madj'-or 

 (L. mdjdr, greater), a species 

 powerfully astringent. 



orthognathous, a., dr-thdg'-ndth-Hs 

 (Gr. ortkos { straight, upright ; 

 gnatkos, a jaw), applied to the 

 type of skull in which the jaw 

 is overhung by the forehead ; 

 having a vertical jaw. 



orthoplocese, n. phi., dr'-thdp-lo' 

 se-e (Gr. orthos, straight ; pldke, 

 a plait), in bot., applied to the 

 Ouciferse which have conduplic- 

 ate cotyledons. 



orthopnoea, n., dr'thdp-ne'-a (Gr. 

 orthos, straight; pried, I breathe), 

 that condition of the respiration 

 in which the difficulty of breathing 

 is increased by stooping, or on 

 lying down, under which, there- 

 fore, the patient has to sit more 

 or less erect. 



Orthoptera, n. plu., dr-thdp'ter-a, 

 also Orthopters, n. plu., dr- 

 thop'-terz, and Orthopterans, n. 

 plu., tir-thdp'ter-anz (Gr. orthos, 

 straight ; ptZron, a wing, ptera, 

 wings), an Order of insects which 

 have their two outer wings dis- 

 posed in straight folds when at 

 rest, as the grasshopper and 

 house- cricket : orthopterous, a., 

 dr-thdp'ter-tis, pert, to ; folding 

 the wings straight. 



orthospermse, n. plu., tir'-tho- 

 sperm'-e (Gr. orthos, straight ; 

 sperma, seed), in bot., seeds 

 which have the albumen flat on 

 the inner face, neither involute 

 nor convolute. 



orthostichies, n. plu., or-tlM-tik- 

 iz (Gr. orthos, straight ; stichos, a 

 series, a row), in bot., applied to 

 the several vertical rows formed by 

 the leaves in a spiral phyllotaxis. 



orthotropal, a., tir'tkdt'-rCp-al, 

 also orthotropous, a., dr-thdt- 

 rdp'us (Gr. orthos, straight ; 

 tropos, direction from trepo, I 

 turn), in boi., having the embryo 



in a seed lying straight towards 

 the hilum or eye, as in the bean ; 

 having the ovule with foramen 

 opposite to the hilum. 

 Oryza, n., dr-iz'a (Gr. 6ruza, rice), 

 a genus of the cereal grains known 

 by the common name * rice, ' 

 Ord. Graminaceae ; the name by 

 which rice was known to the anc. 

 Greeks and Romans : Oryza 

 sativa, sat-lv'a (L. sativus, that 

 is sown or planted), the common 

 rice of commerce. 



OS, n. , ds (L. os, a bone, dssis, of 

 a bone, dssd, bones), a common 

 prefix in anatomical terms 

 denoting ' a bone': osseous, a., 

 ds'se-us, composed of or resem- 

 bling bone: osseous tissue, n., 

 the substance of which bone is 

 composed : os calcis, ds Mls'is 

 (L. calcis, of the heel from calx, 

 the heel), the bone of the heel : 

 os femoris, dsfem'dr-is (L.fem- 

 dris, of the thigh from femur, 

 the thigh), the thigh-bone : os 

 humeri, ds lium'-^r-l (L. humZri, 

 of the shoulder from htimerus, 

 the shoulder), the shoulder-bone ; 

 the large bone of the arm 

 extending from the shoulder to 

 the elbow: os ilium, n., osU'-i'um 

 (see 'ilium'), the haunch-bone, 

 forming part of the pelvis : os in- 

 nominatum, bs m-norn'm-af-tim 

 (L. in, not ; nomen, name), the 

 unnamed bone; a bone consisting 

 of three parts (1) the ilium or 

 haunch-bone, (2) the ischium or 

 hip-bone, and (3) the pubis or 

 share-bone : os ischium, ds isM 

 i-um (see * ischium '), the hip- 

 bone forming part of the pelvis : 

 os magnum, ds mag'-num (L. 

 magnus, great), the largest bone 

 of the carpus, occupying the 

 centre of the wrist : os pedis, 

 ds ped'is (L. pMis, of a foot 

 from pes, a foot), the large bone 

 of the foot : os pubis, n., ds 

 pub'-is (L. pubis, of the pubes 

 from pubes, the pubes), the bone 

 of the pubes ; the share-bone 



