MUCUS

(Lat.) The secretion of the mucous membranes, the most characteristic of which is that from the nasal membrane. Mucus is viscid, and acquires apparent fluidity in water, without being actually di olved; but gives a ropine to it when present to a le amount than 1 per cent. With pure water of the temperature of 950, this appearance ensues in a few hours; but if the apparent solution be filtered, the mucus remains upon the paper and gradually thickens. It may be repeatedly dried and moistened without material change of properties; it, however, becomes le transparent, yellow, and at length has a purulent appearance. When boiled in water it does not harden and shrink, but becomes tough, and on cooling is found to retain its former characters. When dried it is yellow and translucent; and subjected to distillation, it yields carbonate of ammonia and empyreumatic oil, and phosphate and carbonate of lime and carbonate of soda are found in the ash. It is soluble in dilute sulphuric acid, and blackened by the concentrated acid; it is not soluble in acetic acid, but yields but a trace of albumen. According to Henle, mucus consists of the scales of the epithelium which covers the open cavities of the body. This epithelium or cuticle consists of minute cells of various forms, which are continually wearing off and being renovated; it thus yields scales which mix with the watery secretion, and constitute mucus. [s. 790]