When an inflammation either by the operations of nature or the influence of remedies yields, an action is first perceived in the vessel, the dark colour assumes a brighter hue, the tumour lessens, and an effusion takes place from the adjoining exhalants. The effusion sometimes proceeds and relieves the over distended vessel, but there is scarcely an instance of resolution of inflammation, without some effusion, which occasions the adhesion of contiguous membranes. It consists of the serum of the blood, with its proportion of fibrin. This is commonly the termination of the febrile inflammations. In those which depend on the loss of tone, the effusion is of a different kind; and in these, though it relieves the original disease, yet it leaves one scarcely less dangerous. We allude to the effusion of a watery fluid which sometimes follows inflammation of the lungs,producing hydrothorax. When oedematous swellings follow gout or rheumatism, the danger is less.

When nature or art fails in relieving the inflammation by effusion, the texture of the part is destroyed by the continued pressure of the accumulated fluids, and the whole is melted down into one uniform, opaque, white, mild fluid, called pus; and an abscess is said to be formed. The appearance of an abscess is prognosticated by the cessation of the pain and the distention. But to these symptoms, which occur also on effusion taking place, must be added a throbbing pain, synchronous with the dilatation of the arteries, and irregular shiver-ings. After a short time a weight is felt in the part, the pain disappears, and, if on the surface, the tumour is soft, and an evident fluctuation is perceived by the touch. The skin gradually becomes thinner, and a little conical apex appears, generally about the centre of the tumour, which is called its pointing; though frequently the skin only becomes thinner, and the tumour softer in one particular part, above, below, or on either side, indiscriminately, and seemingly from accident.

The nature of purulent matter, as well as its source, has been disputed. We have called it a mild fluid, and undoubtedly to all the senses it is so; yet it seems to dissolve the cellular substance around, and to form for4 itself a cavity greater in proportion to the resistan finds in its way to the surface, where it generally tends. When not the salutary termination of inflammation, it is sometimes highly acrid, as in venereal or scorbutic sores; but its reputed acrimony in other cases arises often from its pressure, which destroys the life of the part, and subjects it to the action of the absorbent vessels. An aneurism, in which there is not the slightest suspicion of acrimony, will do the same.

The source of the purulent matter is said to be the serum of the blood, changed to this form by the process of fermentation. This was the opinion of Gaber and Pringle; but De Haen and some modern authors contend, that it is a morbid secretion from the exhalant arteries. On this subject we find it difficult to form an opinion. Were we to offer any, we should say that it consists of the substance of the vessels and of the cellular membrane dissolved in the serum; but this is an opinion we are not prepared to defend. It is certainly an albuminous fluid, which has, however, a tendency to the putrid fermentation. To produce this fluid a certain degree of excitement of the vessels is requisite. When too considerable, it is sometimes bloody; when the excitement is in too small a degree, it is thin, acrid, and glairy; when in a still less, ichorous. In the latter cases we must apply stimulants and astringents respectively, for only when the pus is of a proper nature and consistence, in the language of surgeons laudable, does it contribute to healing the wound,

There is another fluid which certainly is not laudable, viz. that which is found in scrofulous glands, and which is discharged in consumptive cases. This is of a ragged cheesy kind, surrounded generally with streaks of proper pus, apparently from the inflammation of the coats of the containing cyst. It seems to consist of the gluten of the blood so hardened and condensed that it will not admit of solution. The distinction between pus and mucus is not easy to the inexperienced practitioner. In general, mucus is in rounded masses; pus flows more readily: the latter is softer and whiter, with little globules swimming through it, and, when mixed with a saturated solution of potash, a transparent tenacious jelly is separated, while the same solution produces no such change in mucus.

The fatal terminations are hemorrhage and gangrene. We might have mentioned haemorrhage among the salutary terminations, but they rarely prove so in this climate; yet occasionally a slight bleeding from the neighbouring glands, as a bloody tinge of the sputum in pneumonia, we have thought useful. In general, however, the salutary haemorrhages are copious ones, generally from a neighbouring organ, as from the nose in phrenitis; but these are uncommon in this climate. The fatal haemorrhages occur in the lungs, in the bowels, and bladder, but are not very common terminations.

Gangrene is a fatal termination in the very active inflammations, where the fever runs with peculiar rapidity; or in the very low ones, where want of tone readily admits of considerable dilatation, and consequently compression. In gangrenes the life of the part is destroyed, the redness assumes a livid hue, vesications appear on the surface, and the inflammation is external; pain is no longer felt, a peculiar serenity comes on, with a sinking of the features, which gives a ghastly appearance to the countenance, and the patient dies with every feeling and every expectation of recovery. When a putrid acrimony occurs in the fluids, gangrene is more to be dreaded in inflammations of every kind: it is particularly common in those diseases which occur in jails and crowded hospitals. There is a kind of gangrene which follows considerable irritation and violent pain, independent of great inflammation. In this case the violence of the excitement seems at once to destroy the tone of the part, and it is in this kind that Mr. Pott has found opium so eminently useful. Some authors have supposed gangrene to be occasionally owing to blood effused; but we have no evidence that blood, if preserved from the access of air, is peculiarly disposed to putrefaction. See Erysipelas, Abscessus, and Mortificatio.