osc 



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OST 



forming part of the pelvis : os 

 sacrum, 8s sacrum (L. sacrum, 

 sacred), the bone which forms 

 the basis of the vertebral column; 

 see ' sacrum, ' and ' pubis. ' 



oscula, n. plu., dsk'ul-a (L. osc- 

 ulum, a little mouth from os, 

 the mouth, oris, of the mouth), 

 in zool., the large apertures by 

 which a sponge is perforated ; 

 the suckers with which Tseniada 

 are provided, as in Tape- worms, 

 and Cystic-worms. 



osmose, n., tis-moz', also osmosis, 

 n., os-mdz'fc (Gr. osmos, a 

 pushing influence), the tendency 

 of fluids and gases of different 

 kinds and densities to become 

 diffused through a separating 

 membrane when placed in contact 

 with it ; the action produced by 

 this tendency : osmotic, a., tis- 

 mdt'ik, pert, to or having the 

 nature of osmose ; see * exos- 

 mose ' and * endosmose. ' 



OsmundeaB, n. plu., fa-m&nd'-fre 

 (after Osmund, who first found or 

 used it), the Royal or Flowering 

 Fern tribe, a Sub-order of plants, 

 Ord. Filices : Osmunda, n., 6s - 

 mund'a, a genus of ornamental 

 ferns : Osmunda royalis, rdy- 

 cLl'-is (mod. L. regdlis, royal 

 from L. rex, a king), the 

 Osmund royal, whose roots are 

 said to have emmenagogue 

 virtues. 



osseous, see under ' os.' 



ossicula, n. plu., fc-sik'.ul-a (L. 

 ossiculum, a small bone from 

 tis, a bone, tissis, of a bone), 

 small bones ; used to designate 

 hard structures of small size, as 

 the calcareous plates in the in tegu- 

 ment of the Star- fishes ; ossicles : 

 ossicula auditus, dwd-tt'-us (L. 

 auditus, the sense of hearing, 

 audtttis, of the sense of hearing), 

 the three small bones of the ear 

 malleus, the outermost, is 

 attached to the membrana 

 tympani ; stapes, the innermost, 

 is fixed in the fenestra ovalis ; 



the incus, the third or middle, 

 is connected with both by 

 articular surfaces. 



ossification, n,, ds'-si-fiTc-af-shun 

 (L. os, a bone, tissis, of a bone ; 

 facio, I make), the changing of 

 any soft part of an animal body 

 into bone or bony -like matter : 

 ossified, a., os' si-fid, converted 

 into bone, or a substance like 

 it : ossific, a., os-stf'-ik, bone- 

 forming: ossific dyscrasia, a 

 morbid condition accompanied by 

 bony outgrowths in various parts 

 of the body : see ' dyscrasia. ' 



osteal, a., ost'8-dl (Gr. dsteon, a 

 bone), belonging to bone: osteine, 

 n., dst'e-m, osseous substance or 

 bony-tissue : ostitis, n., dst-it'fe, 

 the inflammation of bone. 



osteoblasts, n. plu., dst-e'd- blasts 

 (Gr. dsteon, a bone ; blastos, a 

 bud, a sprout), the granular 

 corpuscles or cells which cover 

 in a dense layer the osteogenic 

 substance, and lie in its meshes, 

 constituting the formative element 

 of that class of bone not developed 

 from cartilage. 



osteo - chondroma, dst'e-o-lcon- 

 drom'd (Gr. dsteon, a bone ; 

 chondros, cartilage), a name 

 applied to cartilaginous tumours. 



osteoclasts, n. plu., dst-e' 6 -blasts 

 (Gr. ost$dn, bone ; Jclastos, 

 broken, fractured), large com- 

 pound or giant cells, formed in 

 the absorption of bone, and 

 believed to be essential agents 

 in the process of such absorp- 

 tion. 



osteo-dentine, n., dst'e-o-dent'm 

 (Gr. dsteon, a bone ; dens, a 

 tooth, dentis, of a tooth), the 

 substance forming the teeth of 

 vertebrate animals, and covered 

 by the enamel ; a substance 

 intermediate in structure between 

 dentine and bone. 



osteogen, n., dst-e'd-je'n (Gr. 

 dsteon, a bone ; gennao, I pro- 

 duce), the soft, transparent matter 

 in bone which becomes changed 



