Cathartics answer a number of very important therapeutic purposes, and are certainly among the most valuable of the classes of medicines. There can be no doubt, however, that they have been greatly abused. They afford temporary relief under so many circumstances, are generally so easy of administration, and so readily suggest themselves to those who may be too ignorant or too indolent to investigate disease thoroughly, and deduce just indications from an accurate knowledge of its nature, that the temptation to their abuse is almost irresistible. They are the great resource of empirics; and large fortunes have been built upon purgative pills. The use of them has become so common, that, among the vulgar, to take a dose of medicine, or of physic, is equivalent to swallowing a cathartic. Of course, such indiscriminate use of medicines, by no means harmless, must often lead to serious evil; and the physician should be careful not to be seduced, by the facility of practising medicine upon the cathartic plan, into countenancing, by his example, the general rage for self-purgation. He will very often have occasion to administer cathartics; but he should never do so unless in compliance with some clear indication, and should continue them no longer than is necessary for accomplishing the object aimed at.

1. Simply to evacuate the contents of the bowels, is probably the most important indication that cathartics are capable of fulfilling. For this purpose they are used, in the first place, in all cases of fecal accumulation, from habitual or occasional constipation, when the condition cannot be overcome without them. it is not necessary for me to consider here the causes, evils, and treatment of constipation. This subject belongs to the practice of medicine. But there is one consideration which may be appropriately introduced in this place; namely, that, in the treatment of habitual constipation, cathartics should always be regarded merely as temporary agents, to be employed for the sake of obviating injury from the feculent accumulation, but not relied on for the cure. They are not really remedies for the constipation, which must be treated by other measures, calculated to enable the bowels to resume their healthy function. To confide in cathartics alone, would often be to confirm, and even to aggravate the evil. These remarks are especially applicable to the costiveness of dyspepsia.

When, however, constipation is merely occasional, dependent on some temporary cause, which has already ceased, or will soon cease to act, cathartics are to be employed as the chief agent of cure, so far as the constipation itself is concerned. Such attacks occur, now and then, in ordinary health; and the fecal accumulation may become so great as to threaten serious results. Here vigorous cathartics are often requisite, sometimes the most vigorous; and, after the bowels have been thoroughly evacuated, nothing more may be necessary than perhaps some modification of the diet, or other ingesta.

In relation to the constipation which so frequently attends acute diseases, as fevers, inflammations, and various nervous affections, it may be laid down, as an almost universal rule, that the bowels should be kept open, in order to prevent injurious reaction of the feculent matter on the constitution. There are very few diseases, indeed, in which cathartics are not often required on this score. A rule, however, as universal as that of the use of the cathartics, is that, for the fulfilment of the present indication alone, and when no other is offered for their employment, the mildest that will answer the purpose should be selected. it would be unpardonable to purge actively, merely for the removal of the constipation complicating other diseases, when mild measures will answer. Generally, for the purpose here referred to, a laxative should be employed daily, or every other clay. it would seldom be proper to allow the patient to pass more than two days without a stool.

The same remark is applicable to the constipation attendant on pregnancy, in which the pressure of the uterus sometimes interferes with the proper action of the bowels, and laxatives are often useful, to be continued, as may be required, until the temporary cause has ceased.

But it very frequently happens that other indications for cathartics coexist with that offered by simple constipation, which may require medicines of a more energetic character; and great latitude of choice necessarily exists. The physician has the opportunity for the exercise of much acumen and discrimination, in the adaptation of the cathartic, especially indicated by the constipation, to the attainment of other coincident purposes, which are constantly presenting themselves in the course of the disease, and, besides, in accommodating the cathartic employed to peculiar circumstances in the case, as, for example, the state of the stomach, the strength of the system, and the preferences or idiosyncrasies of the patient.

Secondly, cathartics are employed, in compliance with the present indication, to remove unhealthy secretions which may be poured into the stomach and bowels, or other acrid matters which may form in them, through chemical changes in the ingesta, without refei*ence to the existence or non-existence of constipation. Cases of this kind are often presented in sick-headache from acid or acrid matter in the stomach; diarrhoea and cholera infantum, with similar matter, including acrid bile, in the bowels; and various low forms of fever, particularly typhus, or fevers of the typhous type, in which the vitiated secretions may act injuriously, not only by the depressing influence of the substances existing in the bowels, but by their absorption into the circulation, and the consequent vitiation of the blood. in cases of causeless low spirits, hypochondriasis, hysteria, chorea, and various anomalous nervous disorder, especially when attended with a foul breath, it probably not unfrequently happens that the root of the evil is accumulation of offensive matters in the primae viae, operating injuriously, in part at least, through absorption. Whenever there is reason to suppose that this state of things exists, whatever may be the special disease under treatment, there is an indication for this class of medicines.