same time, to the immediate action of cold. Hence, quinsies, and pneumonic inflammations, are more frequent than any others.

247. That the spasm of the extreme vessels takes place in inflammation, is to be further presumed from what is at the same time the state of the whole arterial system. In every considerable inflammation, though arising in one part only, an affection is communicated to the whole system, in consequence of which an inflammation is readily produced in other parts besides that first affected. This general affection is well known among physicians, under the name of the DIATHESIS PHLOGISTICA. It appears most commonly in persons of the most rigid fibres; is often manifestly induced by the tonic or astringent powers of cold; is increased by all tonic and stimulant powers applied to the body; is always attended with a hardness of the pulse; and is most effectually taken off by the relaxing power of blood-letting. From these circumstances, it seems probable, that the diathesis phlogistica consists in an increased tone, or contractility, and perhaps in an increased contraction of the muscular fibres of the whole arterial system. Such a state of the system seems often to arise, and subsist for some time, without the apparent inflammation of any particular part; but such a state of the system renders it likely, that a spasm may, at the same time, readily arise in any of the extreme vessels,

and a particular inflammation be there produced. It does, however, appear also, that the general diathesis frequently arises from inflammation begun in a particular part.

248. I have thus endeavoured, in the case of inflammation, to explain the state of the whole system, as well as that of the part more particularly affected. The latter I have considered as when in its first formation; but after it has subsisted for some time, various changes take place in the part affected; and of these I must now take notice.

SECT. III.

Of the terminations of inflammation.

249. If an inflammation be cured while the state and texture of the part remain entire, the disease is said to be terminated by RESOLUTION.

This happens when the previous congestion and spasm have been in a moderate degree, and the increased impetus of the blood has been sufficient to overcome the spasm, to dilate the vessels, and to remove the congestion, so that the part is restored to its ordinary and healthy state.

A resolution takes place, also, when the increased impetus of the fluids has produced an increased exhalation into the adjoining cellular texture, or an increased excretion in some neigh

bouring part, and has thereby relaxed the spasm, and relieved the congestion, in the vessels of the part more particularly affected.

Lastly, A resolution may take place, when the increased impetus of the blood in the whole system occasions an evacuation, which, though in a distant part, may prove sufficient to take off the phlogistic diathesis of the whole system, and thereby relieve the congestion and spasm of the particular part affected by inflammation.

250. The tumor which appears in inflammation may be imputed in part to the congestion of fluids. in their proper vessels; but is owing chiefly to an effusion of matter into the adjoining cellular texture; and, accordingly, tumours seldom appear but in parts adjoining to a lax cellular texture. If, in this case, the matter effused be only a larger quantity of the ordinary exhaling fluid, this, when the free circulation in the vessels is restored, will be readily absorbed, and the state of the part will become the same as before. But, if the increased impetus of the blood in an inflamed part, dilate the exhalent vessels to such a degree, that they pour out an entire serum, this will not be so readily re-absorbed and, from the experiments of Sir John Pringle, and especially from those of Mr. Gaber, Miscell. Taurin. vol. ii, we learn, that the serum, under stagnation, may suffer a particular change, by having the gluten present in it changed

into a white, opaque, moderately viscid, mild liquor, which we name PUS. When this change takes place in the inflamed part, as it is at the same time attended with an abatement of the redness, heat, and pain, which before distinguished the inflammation, so the disease is said to be terminated by SUPPURATION; and an inflamed part, containing a collection of pus, is called an

ABSCESS.

251. In inflammation, the tendency of it to sup puration may be discovered, by the long continuance of the inflammation, without the symptoms of resolution; by some remission of the pain of distension; by the pain becoming of a throbbing kind, more distinctly connected with the pulsation of the arteries; by the pulse of the arteries being fuller and softer; and often by the patient's being frequently affected with cold shiverings. The period at which this takes place is not determined, but may be sometimes sooner, sometimes later. When the tendency is determined, the time necessary to a complete suppuration is different in different cases.

When pus is completely formed, the pain in the part entirely ceases, and a weight is felt in it. If the collection be formed immediately under the skin, the tumour becomes pointed, the part becomes soft, and the fluctuation of the fluid within can commonly be perceived; while, at the same

time, for the most part, the redness of the skin formerly prevailing is very much gone.

252. In abscesses, while the pus is formed of one part of the matter which had been effused, the other and thinner parts are re-absorbed, so that, in the abscess, when opened, a pus alone appears. This pus, however, is not the converted gluten alone; for the conversion of this being the effect of a particular fermentation, which may affect the solid substance of the part, and perhaps every solid of animal bodies; so it most readily, and particularly, affects the cellular texture, eroding much of it, which thereby becomes a part of the pus. It generally happens also, that some of the smaller red vessels are eroded, and thereby some red blood often appears mixed with the pus in abscesses. Upon the whole, the internal surface of an abscess is to be considered as an ulcerated part.

253. This account of suppuration explains, why an abscess, when formed, may either spread into the cellular texture of the neighbouring parts; or, by eroding the incumbent teguments, be pour ed out upon the surface of the body, and produce an open ulcer.

254. We have here given the idea of an abscess as a collection of matter following inflammation