(From Cathartica 1833 to purge). This word is generally used as expressive of purging medicines; but it implies emetics in ancient authors also.

In this place, however, we must adopt the common language, and speak of purgatives only; a class of medicines of great variety and singular utility. By pharmaceutical authors, they are divided into lenitives, purgatives, and drastics; and by therapeutical writers, into those that act by increasing the evacuations, in consequence of the stimulus applied to the excretory ducts of the different glands, and those that increase the action of the intestines themselves. There are others that act by exciting a commotion in the system, in consequence of their poisonous nature; and these show deleterious effects, immediately on their introduction, by exciting vomiting. Of this kind are the gutta gamba, the seeds of some species of the croton and jatropha, the tobacco, probably the colocynth, and others. Another division, now almost obsolete, is that into phlegmagogues, cholagogues and hydragogues; purgatives that evacuate phlegm, bile, or water: these very nearly correspond to the lenitives, purgatives, and drastics. With the first, often styled minoratives, ec-coprotics have been confounded, but improperly. The last are certainly mild in their operation; but this is not always owing to their moderate stimulus, but often to their want of solubility in the first passages, in consequence of which they act on the rectum only, since they reach that part with little change. Thus sulphur and aloes are eccoprotics, and even the gutta gamba is an ingredient in that recommended by Dr. Fordyce, as the other parts of the formula are not very soluble. We shall therefore follow the pharmaceutical division just mentioned, and then add a few remarks on the eccoprotics.

Lenitives chiefly act by increasing the watery or mucous discharges from the glands, and comprehend all the phlegmagogues af the ancient pharmaceutists. The mildest of this class are the vegetables and the acid fruits. Of the vegetable lenitives,the oleraceae are the principal; and of the acid fruits, the tamarinds, the apples, and the prunes. It is doubtful whether the hesperideae (oranges and lemons), the senticosae (strawberries, raspberries, grapes, gooseberries, etc.), are cathartic, except in considerable quantities. They seem to be directed rather to the urinary organs; though in some constitutions, from idiosyncrasy, probably, they operate as cathartics. All the neutral salts, except the ammoniacal, are in a greater or less degree laxative. To these must be added the supertartrite of the vegetable alkali, viz. the crystals of tartar. The saccharine vegetable substances belong also to the lenitives; as the pulp of the cassia, manna, and, what, with a little latitude, may be referred to the same rank, honey. The vegetable oils are all slightly cathartic; but we use only the olive and the castor oil. Sulphur, from the little change it experiences in the stomach and small intestines, is a cathartic of a similar nature; and to this class phosphorus is added: but, until some safer mode of exhibition is adopted, we would not advise this substance to be employed. The bitters, the gall of animals, the foetid gums, the various balsams, the guaiacum and the myrrh, appear to be occasionally, in a slight but permanent degree, laxative; though not usually arranged in this class. The guaiacum, indeed, is often more active; but this seems frequently to depend rather on idiosyncrasy than a real cathartic power. The foetid gums are excellent vehicles for eccoprotics.

Lenitives, in general, very slightly stimulate the intestines, but seem chiefly to act by increasing the secretions from the glands, whose ducts open into the intestinal canal. They do not increase the heat of the body nor the pulse. They give little uneasiness in the stomach, except from their bulk; and this is chiefly obvious in the saccharine lenitives, and sometimes in the oily. They discharge copious watery faeces; but by no means the substances hardened in the cells of the colon. In many instances, they even lessen heat; and as eccoprotics, unbruised mustard seed, or a clove of garlic, is swallowed, without producing any sensible irritation. The saline lenitives excite thirst; and this may be readily gratified, as warm diluting liquors assist their operation.

Purgatives are more active, excite the action of the muscular fibres of the intestines, and are consequently better adapted to remove the more hardened faeces. Of these there is a considerable variety. The leading distinction is, into those which are astringent, or have no such power. The former are preferred, from their strengthening rather than weakening the bowels. They are supposed, however, to leave a disposition to cos-tiveness; but, while the appearance of astringency leads to a suspicion of this effect, we find little foundation for its existence. All the cathartics, except, perhaps, the saline and oily, render the intestines less irritable; since vessels, stimulated to discharge an unusual quantity of fluids in a given time, sink afterwards into a comparatively torpid state; and, indeed, when the circulating mass is drained of any considerable proportion of its fluids, all the secretions are for a time lessened, until the loss is repaired. But while we cannot deny some subsequent astringent effect to rhubarb, for instance, we cannot admit of its strengthening the bowels by the same power. We have found no effect of this kind, and the continuance of small doses has appeared to be only eccoprotic. When the bowels have been weakened by inflammation, or diarrhoea, it has seemed injurious from its acrimony. This, former practitioners tacitly allowed, by toasting it; which they thought increased its astringency, but really only lessened its cathartic effect.

The distinction between lenitives or drastics, and laxatives, is by no means easy; since by diminishing or increasing the dose of the last, they may, with some propriety, be considered as belonging to the first or second class. This inconvenience, however, attends all natural arrangements; but, in our enumeration of the different medicines, we shall follow them very nearly in the order of their activity.