MUCOR. 



MUDWORT. 



022 



. MUCOR [ENTOPHYTA.] 



' MUCORACEJJ, an order in Lindley's alliance Fungales. The 

 species have a floccose thallus and the spores surrounded by a vesicular 

 yell or sporangium. They are amongst the smallest forms of Fungi, 

 and attack decaying vegetable and animal matters. They are frequently 

 known by the name of Moulds. [MouLDiNESs ; FUNGI; EKTOPHYIA; 

 MILDEW.] 



MUCOUS MEMB1UXE3. [MEMBRAXB.] 



MU'CUNA, a genus of Plant? belonging to the natural order 

 Leyuminotce. The calyx is campanulate bilabiate, with two very 

 caducous bracteoles as long as the tube ; the upper lip broad, entire, 

 and obtuse; the lower lip trifid, with acute segments. The corolla is 

 papilionaceous, with a cordate vexillum incumbent on the wings, much 

 shorter than the wings and the keel, and without callosites. The 

 stamens are diadelphous, with five of the anthers oblong, linear, and 

 the other five ovate and hairy. The seeds oval, roundish, or reniform, 

 with a narrow, oblong, or linear hilum. The species are climbing 

 herbs or shrubs, with pinnately-trifoliate leaves and axillary racemes, 

 which hang down when bearing fruit. 



M. )irurita, Cowitch, has purple flowers in compact ovate racemes ; 

 leaflets hairy beneath, the middle one rhomboidal and obtuse, the 

 lateral ones dilated on the outer edge ; the legumes are oblong, curved, 

 compressed, not keeled, and covered all over with a thick coating of 

 erect white stinging hairs, which turn black in drying and brown 

 when ripe. It is a native of the hedges and banks of the East 

 Indies. 



if. prurient. Common or Stingiug Cowitch, has entire ovate-acute 

 leaflets, smooth above, hairy beneath, the lateral ones oblique at the 

 base, the middle one slightly rhomboidal. The racemes are from 

 12 to 18 inches long, lax, acd many-flowered. The calyx is hairy, 

 pink, with narrow lanceolate segments. The flowers have a disagree- 

 able alliaceous smell ; the vexillum is flesh-coloured, the wings purple 

 or violet, and the keel greeuish-white. The legumes about S inches 

 long, the thickness of the finger, closely covered with strong brown 

 stinging hairs. The seeds oblong, variegated with a white hilum. A 

 mixture of the hairs of these two species form the Cowitch of com- 

 merce. The ripe pods are dipped in syrup, which is scraped off with 

 a knife, and when the syrup has attained the thickness of honey, by 

 means of the hairs becoming mixed with it, it is used as a medicine, 

 and H considered a good anthelmintic, a? it occasions no uneasiness. 

 It is given from a tea-spoonful to a table-spoonful in the morning, 

 fasting. The hairs, when applied to the skin, produce an intolerable 

 and painful itching. A vinous infusion of the pods, 12 to a quart, is 

 said to be a certain remedy for dropsy. A strong infusion of the roots, 

 sweetened with honey, is used by the native practitioners in India 

 in cases of cholera. It is likewise considered a powerful diuretic. 



if. ureni has racemose flowers and legumes clothed with stingiug 

 bristles; the leaflets have a shining tomentum beneath. The flowers 

 are large, white or yellow, with the lower edge of the wings red. The 

 seeds, from their resemblance to an eye, are called by the French 

 Yeux Bourrique, or Aas's-Eyes, and for the same reason the seed has 

 the name Ox-Eye-Bean in our colonies in the West Indies, where the 

 species is a native. 



A rich soil suits these plants, and they are easily raised from cut- 

 tings, but are not worth the trouble of cultivation, excepting for 

 botanical gardens. 



(Don, Dichlamydeoiu Planti; Lindley, Flora, Afedica; Burnett, 

 Out Una of Botany.) 



MUCUS. The fluid which is found on the surface of mucous mem- 

 branes is thus named. The chemical composition of this fluid has 

 not been very accurately ascertained, but its morphological elements 

 have been investigated by Henle and others with much care. 



Dr. Uenle of Berlin (' Ueber Schleim- und Eiter-Bildung,' in Hufeland's 

 'Journ. der Practised. Heilk.,' 1838), was one of the first who deter- 

 mined the true composition of this substance, which had previously 

 presented many qualities that appeared anomalous. He has proved 

 that it always at least contains the scales or cells of epithelium, which 

 cover all the open cavities of the body, suspended in a considerable 

 quantity of watery fluid. 



The epithelium, or cuticular covering of all mucous membranes, 

 consists of one or more layers of minute cells ; and it is deposited not 

 only on the free surfaces of the lar^e open cavities, but is continued 

 into all the canals and ducts of glands that open on the mucous mem- 

 branes. In different situations the form of the epithelium-cells varies 

 considerably; in some parts they are rounded, or polygonal, and flat, 

 adhering to each other in a continued membrane by their adjacent 

 edges ; in others they have a cylindrical or conical form, and ard only 

 attached to the mucous membrane by one of their extremities ; in 

 others they have also a cylindrical or conical form, and their free 

 margins are beset with vibrating cilia. [EPITHELIUM.] 



By the contact of the foreign matters to which all the mucous 

 membranes are exposed in the performance of their functions, or by 

 other processes, the epithelinm cells are constantly being removed, and 

 their plaoe is as constantly supplied by the formation of new cells from 

 the surface beneath. Thus on all the mucous surfaces a more or less 

 rapid process of desquamation and reproduction of cuticle is ever 

 going on ; the superficial layers scaling off, and deep layers beiug 

 produced in a manner exactly similar to that in which, as the outer 



surface of the cuticle of the skin (the epidermis) is removed, fresh 

 layers are deposited on the inner surface to replace them and maintain 

 the thickness of the membrane. 



The superficial layer of epithelium-cells thus removed, not in dry 

 scales, like the epidermis, but mixed with a quantity of watery fluid 

 secreted by the surface of the mucous membrane, constitutes healthy 

 mucus a viscid, ropy, transparent, and apparently homogeneous sub- 

 stance, which is distinguished more especially by the presence of 

 minute epithelium-cells either floating separately or united into small 

 membranous flocculi. Its chief chemical properties are that it mixes 

 with any quantity of water without being dissolved, but swelling up 

 and forming flocculi, does not dissolve in alcohol, aud is not coagulated 

 by heat. 



In addition to the epithelial cells mucus frequently contains round 

 corpuscles, called mucus-corpuscles, which are not easily distinguished 

 from pus-cells. These corpuscles are abundantly secreted in common 

 catarrh. They are regarded as abortive epithelial cells. As these cells 

 increase in diseased conditions, the mucus assumes more decidedly 

 the character of pus. 



It frequently happens that fibrinous coagula are found in the 

 mucus, constituting the peculiar character of the mucus in croup, 

 diphtheritis, pneumonia, Bright's disease, dysentery, and other affec- 

 tions of the mucous membranes. In these cases after the active inSam- 

 ination has ceased, cells are observed in the mucus, which have been 

 called inflammatory globules, or granular cells. Besides these bodies 

 mucus contains fat-globules, and frequently molecular or elementary 

 granules. The latter are seen in incipient diseased conditions of the 

 mucous membranes, as in tuberculosis or cancer. It sometimes con- 

 tains living beings, as Vibrionei and fungoid threads of various kinds. 



The chemical element which forms the basis of mucus is called 

 Mucin, but unfortunately it has not been separated from the morpho- 

 logical elements. In addition to mucin, the mucus contains various 

 extractive matters. It also contains potash and soda, and frequently 

 gives an acid re-action ; this arises from the presence of free acids. 

 Albumen is also present in mucus, and frequently in considerable 

 quantities. With regard to the origin of mucus, Lehmann, in his 

 ' Physiological Chemistry,' has the following remarks. After stating 

 that it does not appear that mucus is formed by any of the glands of the 

 mucous membranes, he says : "Tilanus has drawn especial attention 

 to the circumstance, that epithelial structures are always present 

 wherever there is true mucus. This observation might lead to. the 

 assumption that the formation of mucus is connected with the develop- 

 ment of certain cells, that is to say, that its production occurs simul- 

 taneously with the development of certain morphological elements. 

 Two views here present themselves for our consideration ; one of which 

 is, that the albuminates of the liquor sanguinis become decomposed, 

 under certain hitherto unknown conditions, into the substratum of the 

 epithelial cells and into mucus, whence the latter substance might 

 iu some respects be considered as a secondary product of this cell- 

 formation, so that the mucous juice in the mucus would hold the 

 same relation to the epithelial cells as the spirituous fluid does to the 

 yeast-cells in a mixture which has undergone fermentation. The 

 other view, which seems to be supported by numerous observations 

 made by Scherer and Virchow, refers the origin of the mucus to a 

 partial disintegration of the epithelial cells. All who have followed 

 Frerichs in his observations on the metamorphosis of the cells within 

 the gastric juice, or who have examined them by the microscope i". 

 the preparation of artificial gastric juice, will easily comprehend the 

 gradual solution of the gastric cells and their conversion into a mucous 

 fluid. Such a conversion of cells into a mucous substance would 

 therefore at all events not be wholly without analogy. Scherer and 

 Virchow however go still further, and advance the opinion, based upon 

 several pathologico-histological observations and chemical experiments, 

 that certain colloid substances, and others adapted for the formation 

 of urine, may be converted into mucus under certain conditions which 

 still remain to be explained, and even without any cell-formation ; and 

 hence they regard the latter mo Je of development as associated with 

 the existence of colloid or cartilaginous substances. This view is 

 not only supported by the absence of epithelial structures in many 

 cysts containing mucus, but more especially by the frequently noticed 

 conversion of the gelatin of Whartou into perfect mucus. It appears 

 to us still to require accurate chemical experiments to decide which 

 of these two hypotheses deserves the preference. The elementary 

 analyses which were made by Scherer on a single variety of mucous 

 juice unfortunately d not enable us to decide the question, both 

 because the atomic weight could not be determined, aud because we are 

 still entirely deficient in an accurate analysis of the epithelial cells, the 

 colloid substance, &o. It remains for us to hope that the investigating 

 powers of men like Scherer may before long eurich science with the 

 knowledge necessary for elucidating a subject which is so intimately 

 associated with the advancement of physiology. 



" The localities iu which mucus occurs clearly demonstrate that it 

 is especially designed to serve as a protecting medium to all the parts 

 which are placed in a reciprocal connection with the outer world." 



MUDiTON'E, a local nama for part of the Upper Silurian Rooks 

 of Sir Roderick Murchison. 



MUDVVOKT, the common name of the species of the genus Lima- 

 tella. This genus belongs to the natural order Swophuluriacece. It 



