(From Diarrhoea 2845 through, and to flow). Alvi Fluxus, hypexodos; perturbatio alvi; a too frequent discharge of the contents of the intestines. Dr. Cullen places this genus of disease in the class neuroses, and order spasmi, which he defines a frequent purging; the disease not contagious, and unattended with any primary febrile affection. Of this he forms six species: Diarrhea crapulosa; stercoroso, seu vulgaris; when the excrements are more fluid and more copious than is natural. 2d, Diarrhea biliosa; when yellow faeces are copiously discharged. 3d, Diarrhea mucosa, leucorrhois; diarrhea lactantium; serosa;pituitaria,vel mucosa; in which, either from acrid substances taken into the stomach, or from cold applied particularly to the feet, there is a copious discharge of mucus. 4th, Diarrhea celiaca,called also caeliaca chylosa, and lactea; when a milky liquid, like chyle, passes downwards. 5th, Diarrhea lienteria; when the aliment soon passes through, with little alteration. 6th, Diarrhea hepatirhaea; when the discharge is bloody coloured serum, and not attended with pain. If painful, it is sometimes called a colic.

Those who have been rendered weak or irritable by a hot season or sultry climate, or by being exposed to a putrid vapour, are peculiarly liable to this disease.

The immediate cause is irritation in the intestines; but the causes of this preternatural irritation are numerous: the most frequent are an undue use of purgatives; acidity, or putrescency of the aliments; acrid bile; pus absorbed from abscesses, and carried to the intestines; a laxity of the glands of the intestines; obstructed perspiration; putrid vapours; a translation of the morbid matter of other diseases to the intestines; passions of the mind, etc.

Whatever other symptoms occasionally attend a diarrhoea, besides a too copious and too frequent discharge of the intestines, are accidental.' The loss of appetite, and of strength, are consequences of the excessive evacuations, or of some other attending disorder; sickness and pain are, in many cases, only attending symptoms. While the patient's strength is but little affected by a diarrhoea, it may be generally looked on a salutary rather than morbid evacuation; but sometimes, if neglected or ill treated, the cure is difficult.

Diarrhoea, in its most unlimited sense, is a discharge from the bowels; and, in this view, its explanation is peculiarly difficult. The principal distinction which arises is, whether the cause be connected with the bowels, or with other organs; in fact, whether diarrhoea be idiopathic or symptomatic. But this distinction we shall have little occasion to employ, since the greater number of instances are owing to substances actually present in the intestines.

The most obvious species is that kind which arises from the ingesta, whether these in their quantity or quality offend. In either case, the first symptoms arise in the stomach; and, if the patient cannot ascertain the fact from recollecting what he has eaten, he may be reminded of it, by the taste arising in his mouth, the aversion which he feels on recollecting any part of his former diet; from the nidorose eructations, resembling the taste of rotten egg, or even a putrid taste on the back part of the tongue. In such circumstances, no medicine will, in general, succeed, without evacuating the sto-mach; but to this consideration we must return. When the ingesta pass the stomach, they sometimes excite commotions from their action in the intestinal canal. They then usually pass off; but there are instances where they are retained, particularly in the colon, by a spasmodic constriction; and the increased action which they excite is sometimes continued from increased irritability alone. In the first instance, considerable pain usually attends; in the second, the stools are watery, without pain.

Another kind of diarrhoea, confined to the bowels, is from an increased discharge of the fluids poured in from their excretory ducts. The principal fluid is bile; and diarrhoea arises from this fluid in many different circumstances. An increased flow of bile is sometimes owing to continued heat only, and it is then attended with vomiting, as in cholera; sometimes from a previous obstruction of the biliary ducts, when the preceding jaundice will point out its cause; occasionally from the exciting passions of the mind; from the bites of vipers; from worms; from poisons; from congestions in the liver; from cold; or the cold fit of fevers.

Of the other glands whose ducts open in the alimentary canal, we have a less perfect knowledge. The pancreas only is an object of our sense, and its functions are little known. It is probable, however, that its fluid resembles the saliva; and, when we find mercurials employed in friction, instead of affecting the salivary glands, stimulate the intestines, we naturally ascribe it to an increased discharge of the pancreatic fluid.

The whole of the canal is covered, however, with mucous glands; and we know that, when the perspira-tion is obstructed, the whole mucous membrane compensates for the defect, by an increased discharge. It is said, and, we believe, with some truth, that the milk is occasionally absorbed and deposited on the intestines; we can add, after what has been said on the subject of Coeliaca passio and Diabetes, q. v. that the unapplied aliment sometimes takes the same course.

In cases of teething, we might consider the increased action of the salivary glands as similar to the increased discharge from the pancreas. We omitted mentioning it, however, under this head, because it is supposed that the irritation communicated through the whole membrane contributes to the effect. We dare not either deny or confirm this opinion; but it receives some support from opium being the most effectual remedy.