CONCRETION, in medicine, a formation of solid unorganized masses within the body, either by chemical precipitation from the fluids, or by the accidental aggregation of solids introduced into the system from without. In the former case, a C. is termed a calculus (q.v.); in the latter, the C. may be either wholly composed of solids foreign to the body, or these may be mingled with the elements of the secretions, as with mucus, or calculous matter. Thus beans, peas, needles, etc., introduced into the cavities of the body, have become the nuclei of concretions, by attracting around them mucus, or crystalline deposits from the urine. The most remarkahle forms of C., however, are perhaps those formed in the stomach and intestines of man and the lower animals, from the more solid and indigestible parts of the food, or of substances improperly swallowed. Thus, young women have been known to acquire time habit of swallowing their own hair to a great extent; and very large concretions have been thus formed, which have proved fatal, by obstructing the passage of food. The use of oatmeal in large amount has also been
found to lead to concretions, especially when eaten coarsely ground and unboiled ; such concretions have commonly been found in the intestines. The excessive domestic use of magnesia in the solid form as a laxative, has been known to have a similar effect. In certain animals, intestinal concretions are not uncommon, and grow to an immense size; they used to be greatly prized as antidotes, and were used in medicine under the name of bezoars (q.v.). In certain forms of morbid deposits, such as fibrous tumors (see Tumon), and in tubercle (q.v.), concretions not unfrequently form; they are for the most part composed of phosphate of lime.