(From in flammo,to burn,) phleg-mone; Phlogosis; inflammation. Phlegma, Hippocrates; oxyphlegmasia; a topical pain, with an injury of the functions of an internal organ, attended with inflammatory fever, and the appearance of a buffy coat on the blood. External inflammation is characterised by a redness, heat, and a painful tension of the affected part.

The most obvious idea which the symptoms of inflammation suggest, is that of an accumulation of blood in the vessels, and its confinement in a given part. The conclusion, however, is too general; for the veins of the part are often swollen, and the secretions from the neighbouring glands sometimes increased in quantity. The accumulation has, however, suggested the idea of its arising from a stimulus, and the confinement of the fluids in the part the idea of obstruction. It is obvious, that a stimulus will produce inflammation; but when this is removed, the inflammation ceases. Obstruction then has been the leading principle in every theory of inflammation, especially when pathologists had remarked, that obstruction alone excites the action of the vascular system.

The source of this obstruction has differed according to the fancy of the enquirer. It was first supposed to be too great viscidity of the blood, and we were triumphantly shown the dense buffy coat on its surface, when drawn; but we now know, that the whole mass of the crassamentum is not preternaturally dense or viscid, for that the basis of the clotis loose in proportion to the density of the surface. Another opinion was, that, as there appeared to be a series of vessels of decreasing diameters, and evidently some into which the red globules were unable to enter from their size, inflammation might consist in these globules being impelled into vessels not adapted for them, where they were confined, occasioning, from their obstruction, inflammations. This is the famous error loci of Bocrhaave, and there is no doubt of this"error" taking place; but we shall find it to be an effect, not a cause. Dr. Cullen considers the obstruction as owing to spasm."that a spasm of the extreme vessels takes place in inflammation is presumed, he observes, from what is at the same time the state of the whole arterial system. In all considerable inflammations, 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 to physicians under the name of diathesis phlogistica. It most commonly appears in persons of the most rigid fibres; is often manifestly induced by the tonic or astringent power of cold; increased by all tonic and stimulant powers applied to the body; always attended by a hardness of the pulse; and most effectually taken off by the relaxing power of blood letting. From these circumstances it is probable, that the diathesis phlogistica consists in an increased tone, or contractility, and perhaps contraction, of the muscular fibres of the whole arterial system."

Thus rested the state of opinions for many years, when a new opinion arose in the school of Edinburgh; an opinion, however, of private teachers rather than of the professors, that inflammation was owing to a debility of the vessels of the part affected, admitting of considerable distention; or, at least, to a disturbance of the balance between the action of the larger vessels and that of the capillaries, in which inflammation is seated. This opinion has been published by Dr. Wilson, in his third volume on Febrile Diseases, and attributed to Dr. Lubbock, or a Mr. Allen, who, we believe, gave a course of lectures on physiology in that university. We had, many years since, formed a similar opinion, when digesting the observations already offered on fevers, which attributes the phenomena of these to a change in the equilibrium of the circulation. We mention this circumstance neither to detract from these authors' credit, nor to add to our own; but, as some confirmation of the claim, we may suggest the consistency of this doctrine, with the view we have given of fever in general.

In our explanation of fever, we attempted to prove that debility was the first change which took place; and, in all the varieties and changes of appearances, debility, we remarked, was always the leading feature. With a view to inflammation, we observed, that, while there was a quiescence of the capillaries, probably a spasm, since debility is its general and principal cause, the action of the sanguiferous system was excited, but that the excitement was partial. If, then, from any cause, this action is excited in a peculiar degree, and if any debility in a given part concurs, inflammation will be the consequence. These are not hypothetical positions. Inflammations chiefly occur in the young, the robust, and sanguine, whose habit, or diathesis, is inflammatory, and from hence called phlogistic, a term derived, like inflammation, from fire, before phlogiston had an existence in chemistry. The phlogistic diathesis consists in a strong action of the arterial system, and increased tone and vigour of the active powers of the circulation, which arc evident from the strong, hard pulse, and the general firmness of the whole habit. If any of fever happens, it will be evident that the action of the arterial system will be, in such constitutions, inordinate. The partial debility is also equally conspicuous. No more certain cause of rheumatism exists than topical cold, after the part has been unusually heated; of peripneumony, than previously having breathed warm air; and of any inflammation, than from the same part having been formerly affected. with the same disease. All these circumstances point out previous topical debility, quiescence which admits of accumulation, in which inflammation seems to consist. This forms, however, the extreme case: various are the intermediate ones, in which, though the balance is disturbed, the vis a tergo is more or less violent in proportion to the debility, or the debility more or less considerable in proportion to the former force. When in a healthy state a part is rubbed or irritated, a redness comes on, which on the cessation of the cause again recedes. This can scarcely be called inflammation, for it is not a disease. In fact, the balance of the circulation is not disturbed; but if the motion of the fluids is interrupted, and their return by the veins impeded, the usual consequences of obstruction follow; the vis a tergo is increased, the vessels distended and weakened. If, on the contrary, a part is weakened, as by cold, the fluids accumulate without any increase of the vis a tergo, become red and livid, but by the gradual approach of warmth again recover their usual appearance. This again is not disease; but if the cold is farther continued, so that the power of the arteries behind cannot propel the fluids, chilblains and gangrene ensue.