MUCOUS CORPUSCLES. [ 522 ] 



MUSCA. 



by ail even joint; opening by an umbilicus. 

 Spores oblong, very large. Filaments cses- 

 pitose, tubular, continuous, and shining. 



Hydrophora. Peridiole subglobose, mem- 

 branous, dehiscent, at first crystalline, aque- 

 ous, then turbid, and at length indurated, 

 persistent. Columella absent; spores simple, 

 conglobated. 



Mucor. Peridiole subglobose, separating 

 like a cap (leaving an annular fragment 

 attached) from the erect, simple, continu- 

 ous pedicel, or bursting irregularly ; colu- 

 mella cylindrical or ovate, spores simple. 



(?) Acrostalagmus. Peridioles globose, 

 with a columella, at the points of doubly 

 verticillate branches from an erect pedi- 

 cel. 



Pilobolus. Peridiole globular, separating 

 like a cap from the short stalk composed of 

 a single cell, attached on a unicellular rami- 

 fied mycelium ; columella conical ; spores 

 very numerous, free in the peridiole. 



Syzygites. Filaments erect, simple, very 

 much branched above, branches and branch- 

 lets di- or trichotomous, fertile branches 

 forcipate, bearing pairs of opposite internal 

 clavate branches, which subsequently coa- 

 hsce. 



MUCOUS CORPUSCLES. See MOUTH. 



MUCOUS MEMBRANES. Those in- 

 ternal canals and cavities of the body which 

 open externally, as the alimentary canal, 

 bladder, &c., are bounded by what may be 

 regarded as internal prolongations of the 

 skin, called mucous membranes. 



They consist of four layers: 1, an inner- 

 most or epithelial layer, corresponding to 

 the cutaneous epidermis ; 2, a subjacent 

 structureless basement membrane, which is 

 not always separable and demonstrable or 

 present; 3, a layer of variable thickness, 

 consisting of connective and elastic tissue, 

 well supplied with blood-vessels and nerves, 

 often containing numerous small glands, 

 frequently furnished with conical or filiform 

 processes termed papillae or villi, and some- 

 times traversed by muscular fibres. These 

 three layers form the proper mucous mem- 

 brane ; and are supported by, 4, an outer- 

 most submucous layer or coat, composed of 

 the same elements as the last, but much 

 more lax in structure, and frequently con- 

 taining fatty tissue. 



The mucous membranes are usually very 

 vascular; and injected preparations of them 

 are very beautiful, and to some extent cha- 

 racteristic. 



The size and form of the epithelial cells 



are to a certain extent also characteristic, 

 especially those of the uppermost layer; 

 and a knowledge of the peculiar structure 

 in individual cases is of use in determining 

 the source of morbid mucous products mixed 

 with epithelial cells. 



See the special articles. 



MUCRONEL'LA, Hincks, = ZeprZmpt. 

 Zoary incrusting ; cells with a rounded or 

 semicircular orifice, and an anterior tooth. 

 Several species; on rocks, shells, and sea- 

 weeds. (Hincks, Polyz. 360.) 



MUCUS. Natural mucus contains no 

 essential morphological elements. As ordi- 

 narily met with, it often, however, exhibits 

 some epithelial cells, mucous corpuscles, 

 and numerous granules; and the peculiar 

 mucous matter has a striated or fibrous 

 appearance, mostly produced artificially. 

 The abnormal elements are principally those 

 of inflammation. 



BIBL. See CHEMISTRY, ANIMAL. 



MUD. The organisms found in mud are 

 very numerous ; they consist principally of 

 Diatomaceaa and other minute Algae. The 

 surface of mud is often covered with yel- 

 lowish or greenish layers, composed almost 

 entirely of these organisms. The most 

 beautiful and most numerous forms of Dia- 

 tomacese are found in the mud of sea-water, 

 or that of tidal rivers. On exposing a bottle 

 of mud and water to the light, they will 

 rise to the surface of the mud, some adher- 

 ing to the side of the bottle next the light, 

 and can then be easily separated. The sur- 

 face of freshwater-mud frequently appears 

 of a blood-red colour, from the presence of 

 Tubifex rtvulonim. 



M'UREX'IDE. See AMMONIA, PURPU- 



RATE OF. 



MURIATE OF AMMONIA. See AM- 

 MONIA, HYDROCHLORATE OF. 



MU'RIFORM. The term applied to 

 flattened six-sided cells placed one above 

 the other in one or more rows, like bricks 

 in a wall. 



MU 'SA, Tournef. A genus of Musacere 

 (Monocotyledonous Flowering Plants), com- 

 prising the Bananas and Plantains. The 

 fibro-vascular bundles of Musa aftbrd ex- 

 amples of spiral vessels with numerous 

 spiral fibres (see SPIRAL STRUCTURES). 

 Musa textilis affords the fibre called Manilla 

 hemp (see PI. 28. fig. 7). See FIBROUS 

 STRUCTURES. 



MUS'CA, Linn. A genus of Dipterous 

 Insects, of the family Muscidae. 



Among the well-known species, all of 



