MUCOUS CORPUSCLES. 



[ 443 ] 



MUSCA. 



III. MUCOR. Peridiole subglobose, se- 

 parating like a cap (leaving an annular 

 fragment attached) from the erect, simple, 

 continuous pedicel, or bursting irregu- 

 larly ; columella cylindrical or ovate, spores 

 simple. 



IV. EUROTIUM. Peridiole membranous, 

 sessile, at length bursting irregularly; spores 

 globose, very small, gelatinous, diffluent in 

 water ; filaments of the mycelium radiating 

 from the base of the peridiole. 



V. ^EGERITA. Peridiole spherical, very 

 fugacious; sporidia soon scattered like white 

 meal over the gruraous receptacle. 



VI. PILOBOLUS. Peridiole globular, 

 separating Hke a cap from the short stalk 

 composed of a single cell, attached on an 

 unicellular ramified mycelium; columella 

 conical; spores very numerous, free in the 

 peridiole. 



VII. SIZYGITES. Filaments erect, sim- 

 ple, very much branched above, branches 

 and branchlets di- or tri-chotomous, fertile 

 branches forcipate, bearing pairs of opposite 

 internal, clavate branches, which subsequently 

 coalesce. 



Excluded genera. Ascophora == Mucor ; 

 Thelactis = Mucor ? ; Rhizopus = Mucor ; 

 Acrostalagmus = Botrytis. 



MUCOUS CORPUSCLES. SeeMouTH. 



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 ; 

 next comes 3, a layer of variable thickness, 

 consisting of areolar 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 sometimes tra- 

 versed by muscular fibres. These three 

 layers form the proper mucous membrane j 

 and are supported by 4, an outermost 

 submucous layer or coat, composed of the 

 same elements as the last, but much more 

 lax in structure, and frequently containing 

 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. 



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 

 Diatomaceae and other minute Algae. The 

 surface of mud is often covered with yellow- 

 ish or greenish layers, composed almost 

 entirely of these organisms. The most beau- 

 tiful and most numerous forms of Diatoma- 

 ceae 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 adhering to 

 the side of the bottle next the light, and can 

 then be easily separated. The surface of 

 freshwater mud frequently appears of a 

 blood-red colour, from the presence of Tu- 

 bifex rivulorum. 



MUREXIDE. See AMMONIA, PURPU- 



RATE OF, p. 29. 



MURIATE OF AMMONIA. See AM- 

 MONIA, HYDROCHLORATE OF, p. 28. 



MUSA, Tournef. A genus of Musaceae 

 (Monocotyledonous Flowering Plants), com- 

 prising the Bananas and Plantains. The 

 fibro-vascular bundles of Musa afford ex- 

 amples of spiral vessels with numerous 

 spiral fibres (see SPIRAL-FIBROUS STRUC- 

 TURES). Musa textilis affords the fibre 

 called Manilla hemp (see PI. 21. fig. /). See 

 TEXTILE SUBSTANCES. 



MUSCA, Linn. A genus of Dipterous 

 Insects, of the family Muscidae. 



It would be of little use to detail the cha- 

 racters of this genus, as they vary so much 

 according to different authors. Among the 

 well-known species (all of which have been 

 formed into new genera), we may mention : 



Musca domestica, L., common house-fly. 

 Third joint of antennae thrice the length of 

 the second; style plumose, eyes reddish- 

 brown, front of head white, the rest black ; 

 thorax blackish-gray with four longitudinal 



