Diarrhoea (Gr. siappeiv, to flow through), a disease characterized by frequent loose alvine discharges. In a proper system of nosology diarrhoea would scarce find a place; it is a symptom rather than a disease, and is produced by a number of different pathological conditions. It is present in the course of typhoid fever, is a frequent accompaniment of phthisis, and is sometimes an attendant upon albuminuria and other forms of blood poisoning; it is caused by inflammation and ulceration of the bowels. Those slighter forms of the complaint only will be noticed here which are independent of constitutional causes, and which are produced by a temporary irritation or sub-inflammation of the intestinal mucous membrane. Diarrhoea is often caused by the use of crude and indigestible food, or even by food ordinarily wholesome taken in too great quantity or variety. Fruit, particularly when acid and unripe, uncooked vegetables, as cucumbers and salads, food in a state of incipient decomposition, the flesh of immature animals, as young veal, etc., are all liable to act upon the bowels. Certain articles, as mushrooms, shellfish, the richer varieties of ordinary fish, as salmon, from peculiarity of habit disagree with particular individuals and produce diarrhoea.

The same is true of a total change of diet; food perfectly wholesome to those accustomed to it, and the water used habitually in certain districts of country, often cause bowel complaints in the stranger. Emotions of the mind, particularly grief and anger, in some persons promptly occasion an attack of diarrhoea; others are affected in the same way by sudden changes of temperature, wet feet, or exposure to cold. Where diarrhoea is caused by the ingestion of food rendered irritating by its quantity or quality, the purging itself soon removes the cause of irritation and the diarrhoea ceases; if this should not be the case, a moderate opiate or an anodyne combined with an astringent are all that is necessary. When diarrhoea is de-pendent on exposure to cold, a bland, unirri-tating diet, the warm bath, and the use of opium or of opium and ipecacuanha in small doses, may be had recourse to; in such cases the patient is generally benefited by wearing a flannel bandage around the abdomen. - Infants at the breast sometimes suffer from bowel complaint; here it is commonly caused by overfeeding.

Ordinarily nature provides against this by the facility with which the infant vomits; the stomach frees itself from the excess of food, and no mischief is done; but when the infant does not vomit, diarrhoea is caused, and undigested curd is present in large quantity in the evacuations. The obvious remedy is the prolongation of the intervals at which the child is suckled. During dentition in infants, from the large quantity of blood sent to the digestive organs, and the rapid evolution which they are undergoing, the bowels are irritable, and diarrhoea often supervenes; this is best guarded against by care in the diet and a proper observance of hygienic regulations. - A popular remedy for diarrhoea, especially in cases which precede an attack of cholera, is a mixture of equal parts of laudanum, tincture of rhubarb, spirits of camphor, tincture of capsicum, and essence of peppermint, taken in doses of 20 to 30 drops in a little water at frequent intervals until relief is afforded. (See Cholera.)