In cases of diarrhoea following suppressed perspiration, we considered the discharge as merely vicarious. It is, however, sometimes inflammatory; and it was necessary to separate the consideration in a practical view, from the following circumstance. A diarrhoea sometimes follows measles, which, Sydenham tells us, cannot be suppressed by the usual remedies, but by antiphlogistic plans, and particularly bleeding.

Diarrhoea, we have said,arises from acrid poisons; and these, even when they have been discharged, leave the intestines in so irritable a state, that even the common ingesta excite violent and irregular action. Sometimes even extreme general irritability will occasion a similar effect; and any agitation, even from the depressing passions, will occasion copious discharges from the bowels. This disease occasionally attends fevers, and is said to be sometimes critical, which means, in the language of the ancient physicians, that the concocted morbid matter is thrown out by the glands of the intestines, probably the liver. Though we admit neither of the theory nor of the comment, the fact is certain, and will be found to admit of a different explanation. We now mention it merely to say, that, if in fever the pulse becomes fuller, softer, and slower, the skin more moist, without faintness, though the discharges by stool are copious, they should not be hastily checked.

The bowels suffer from another cause. When internal suppuration takes place, the discharge is sometimes lessened, and the purulent matter apparently evacuated from the intestines. It is seemingly absorbed, and again deposited. In cancers we have more than once known this metastasis, as it is called, to take place; and in phthisis it is not uncommon, especially when there is no morning perspiration, or this discharge disappears, or is checked. It frequently attends peripneumony, and is then a dangerous symptom, as it prevents the natural solution of the disease by expectoration; sometimes it attends gout, when it brings back an almost extinguished paroxysm.

Diarrhoea sometimes continues long without evacuating the offending substance. We must not, therefore, conclude, from its continuance, that the intestines are properly emptied. In fevers it supervenes, or is produced by the most active purgatives, without properly discharging the contents of the canal, which only appear on the solution of the disease. When diarrhoea has long continued, it is attended with tenesmus, an irregular action of the rectum, suggesting the idea of a discharge impending, without effect. Sometimes the ' abraded mucus exposes the small vessels, and a little blood is evacuated. It is then said to be dysenteric; but no two diseases arc more essentially distant than diarrhoea and dysentery, as we shall soon demonstrate. The mucous diarrhoea approaches most nearly to dysentery; but this is either owing to acrid cathartics or sometimes to cold.

Diarrhoea is seldom fatal but in exhausted constitutions, where it is generally a symptom of some highly dangerous disease; or where the tone of the intestines is so completely destroyed, that the aliment cannot be retained a sufficient time to be digested. In general, when it has continued for a long period, it is seldom completely removed; and, in such cases, when it has ceased for a time, the slightest occasional causes have induced a relapse.

The cure of diarrhoea is sometimes easy; but it frequently baffles our utmost skill. When the symptoms, already described in the stomach, lead to a suspicion that irritation is kept up by acrid substances in that vis-cus, an emetic should be premised. This, indeed, is generally necessary in every case where the diarrhoea continues obstinate. It relieves the stomach from acrimony, checks the increased peristaltic motion downward, gives it an opposite direction, or determines it to the skin: in each way it is useful. After the emetic, it is necessary to procure some respite, and opiates may be employed with safety. By lessening or stopping the peristaltic motion, we relax any spasmodic stricture which may prevent the discharge of offending matter; and the gentle laxatives afterwards required, will have a more salutary effect. By thus alternating the opiates and laxatives, we at last succeed in relieving the bowels from the irritation of offending matter, and moderately warm astringents will complete the cure.

The bilious vomiting will be sufficiently understood by what has been observed under the article Cholera. We can only add in this place, that while the discharges continue dark and fetid, no astringents should be employed, and we can only allow occasional rest by a slight opiate after it, and the laxatives must be soon repeated.

When a bilious diarrhoea has followed a suppressed evacuation of bile, or when it arises from passions, from worms, the bites of poisonous animals, etc. it requires regulation, rather than immediate suppression, and we may still alternate the opiates with the laxatives; but emetics are unnecessary. The diarrhoea, from congestions, in the liver, attends those who have lived long in, and been affected with the bilious diseases of, warm climates. It is a symptom of infarcted liver, and the cure will depend on the removal of the principal complaint. When from the congestion, in consequence of the cold fit of fevers, we must endeavour to relieve the fever by the remedies to be afterwards pointed out.

The diarrhoea, which arises from mercurials externally applied, we have attributed to their action on the pancreas; and the medicine must, in that case, be remitted, opiates employed, and perspiration excited by warm diluting liquors. When the kindred fluid, the saliva, excites the action of the intestines, in the teething of children, we can only lessen it, and diminish the irritation by opium. It must, however, be recollected, that a diarrhoea in teething is most salutary, and that it should be regulated, not checked.

The most frequent cause of diarrhoea is an affection of the mucous membrane, either when its action is increased to supply, with the other glands, the deficiency of perspiration, or when, from this or a specific virus, as in the measles, these glands are inflamed. In such cases the ipecacuanha, either in active doses, as an emetic, or in milder ones, with opium, as a diaphoretic, is of considerable service. The warm bath also, general or topical, is essentially useful. In the last case, Sydenham recommends bleeding; but by regulating the discharge only by diaphoretics, and interposing mild laxatives, we have always succeeded in combating it. In general, diarrhoea, from cold, should be treated like a catarrh, which it really is; and we may be less anxious to keep up any action of the bowels than in the other cases. A similar "disease arises from the metastasis of milk, of any unassimilated nourishment, or of purulent matter. These also may be checked; but the offending fluids will find their way by other excretories, and little advantage can be gained, unless the original cause be removed. In the instance of the milk only can we form any reasonable expectations. This is the diarrhoea that attends puerperal women, and we should be cautious in checking it, though we must equally prevent its excess. In these cases the ipecacuanha, as an emetic, followed by the columbo root, and the careful, but occasional, exhibition of opium, will best succeed. Every means must, however, be attempted to bring back the milk to its natural channel.

When the diarrhoea is chronical, moderate astringents and tonics, warm feet, exercise on horseback, and avoiding the depressing passions, afford the most reasonable expectations of relief. Opiates, with demulcents, as in the old pulvis e bolo cum opio, the modern pulvis e creta compositus cum opio, are often essentially necessary.

The safest astringents in diarrhoea are the opiates, especially if joined with ipecacuanha. The tormentil, the ca techu, the gum kino, the oak bark, and the logwood, may be occasionally employed. We have placed them nearly in the order of their strength; for the tormentil is seemingly the strongest. The logwood appears to owe its utility, in part, to its mucilage, and is more effectual where the mucous coat of the intestines is abraded. In such cases, which often follow the use of acrid cathartics or poisons, this, with thick gruels, chiefly of rice, a decoction of althaea, with gum arabic, and every other mild demulcent, is of singular utility.

Opiates may be sometimes given in clysters, and they are said to affect the head in a less degree than when swallowed. They relieve more certainly, in this way, the troublesome tenesmus; which is often greatly mitigated also by the pulv. e bolo cum opio, interposing the mildest laxatives, as soap or castor oil.

Soap, when joined with wax, which thus becomes soluble in our fluids, is often highly useful when the mucus of the bowels is abraded, or tenesmus is troublesome. A little opium, and occasionally the Dover's powder, joined with these remedies, renders it more effectual.

It may be remarked, that we have not mentioned rhubarb, on which former authors seem to have a considerable dependence in this complaint, from its supposed subsequent astringency. We have not found it, however, superior to other purgatives: yet occasionally, in small doses, it seems to strengthen the bowels; and those who depend on its astringent qualities may supply this remedy, where we have mentioned purgatives in general.

See Aretaeus; Lommius; Wallis's Sydenham; For-dyce's Elements, part ii.; Dr. Pye's Observations on the Use of Ipecacuanha, in the London Med. Obs. and Inq. vol. i.; Cullen's First Lines, vol. iv. Diarrhoe'a carnosa. See Dysenteria. Diarrhoe'a cholerica. See Cholera morbus. Diarrhoe'a urinosa, or ex oure. See Diabetes.