Inflammation is characterized by much variety and anomaly. On the one side, it recedes so far from the foregoing description of the process, that it has been attempted to distinguish certain forms as spurious inflammation. On the other side, its gradations into mere hyperemia and a preternatural amount of plasma-exudation (nutritive irritation) are so imperceptible, that discrimination becomes a matter of difficulty, the greater, perhaps, that such processes frequently do become exalted into, and do alternate with, inflammation.

Every hyperemia may attain the point of inflammatory stasis.

(a.) Active hyperaemia, the same in origin with inflammatory congestion, is developed into sthenic, or active, inflammation.

(b.) Passive hyperaemia, - the result of direct, centrical or peripheral palsy of the entire nerve-apparatus of an organ, - becomes passive, asthenic inflammation. To it belong, amongst others, all hypostatic inflammations, occurring in dependent parts during the progress of adynamiae and marasmi, and the asthenic inflammations in organs paralyzed by concussion, complex injuries, or by direct central influence, - for example, of the bladder, in paraplegia. Many of them have a humoral origin, a dyscrasial disturbance giving rise to paralysis either central or directly peripheral. The hyperemia and stasis are characterized, in the absence of pain and increased temperature, by very dark livid redness, partly of injection, but for the most part of imbibition. Their products, conformably with the humoral elements, are poor in coagulable material, discolored by adherent blood-pigment, spuriously reddened, sero-albuminous, sero-purulent. Frequently the stasis becomes absolute, degenerating into necrosis of the blood and of the diseased texture; in one word, into gangrene.

(c.) Mechanical hyperaemia, as we have seen, commonly determines exudation of serum [oedema], and this not alone from the true capillaries, but also from the larger veins. By intense mechanical obstruction, the hyperaemia is raised to a stasis marked by very deep redness, great tumefaction, numerous lacerations of vessels, and hemorrhage. It deposits the usual coagulable products, but often degenerates, with complete paralysis of the organ affected, into absolute stasis and gangrene.

The Course Of Inflammation

The Course Of Inflammation is acute or chronic; all else being equal, sthenic, and traumatic inflammations, and (amongst those due to internal causes) such as result from a fibrino-croupous crasis, are marked by their acute character. Asthenic inflammations, on the other side, and of these, more especially the ordinary hypostatic, incline to a chronic course. Chronic inflammation is variously modified.

(a.) Inflammation may tarry unwontedly long at any one of its stages. It is in unison with the causal conditions upon which hypostatic inflammations depend, that their stasis should be abiding. The congestion is, moreover, often only very gradually brought about.

(b.) There are inflammations in which a decided stasis is most probably never arrived at; the process consisting in prolonged congestion, with a slackening of the circulation, bordering upon stasis. Arrested processes of this kind give rise to exudations, poor in coagulable materials, serous in kind, and prone to accumulate either by slow degrees or by sudden impulses.

(c.) Chronic inflammation consists in a linked succession, stage for stage, of inflammations more or less acute. Amongst the most marked are those occurring in the vascularized products of an antecedent inflammatory process, more particularly in the pseudo-membranous products of inflammation upon serous membranes.

(d.) Inflammations productive of pus and ichor, whether of external or internal origin, are, for the most part, essentially chronic processes imitative of a secretive function.

In point of degree and extension, inflammations offer the greatest possible variety. For the degree of intensity of the inflammation, the intensity of the external appearances, especially redness and tumefaction, together with the quantity and quality of the products, affords a criterion. This, however, applies exclusively to inflammations due to local external causes. In inflammations kindled out of an internal humoral element, the mildness of the stasis and of its symptoms is often strikingly disproportionate to the quantity and character of its products. Even the former kind is subject to frequent exceptions: thus, purulent exudation, which is commonly regarded as the product of a very intense stasis, not unfrequently occurs in great abundance under slight symptoms.

The Extent Of An Inflammation

The Extent Of An Inflammation, that is, its diffusion over one or more organs, depends both upon its occasional cause and upon accessory circumstances. Inflammations evoked by dyscrasial agency, very commonly assault large organs, or at least considerable sections thereof, very frequently several like-named or kindred organs, at once, or in rapid succession, - for example, serous, mucous, follicular formations.

Inflammation is not essentially modified by anatomical differences of organs and tissues. We may here, however, remark that -

(a.) Organs differ greatly in the proneness to inflammation from an internal humoral cause, there being a certain relation of organs to special crases. Frequently, however, peculiar extraneous impulses concur to localize a crasis upon a particular formation; take, for instance, the localization of the puerperal crasis upon the peritoneum, a part enlisted both in the act of parturition and in the puerperal uterine process.

(b.) Vascularized new growths, like normal textures, may become the seat of inflammation, luxuriate in growth, and increase in substance, or else decline and perish. Sloughing and luxuriance of growth are here occasionally concurrent processes. Tender, budding formations are especially apt to become destroyed by inflammation, at the same time that a more vigorous germination is becoming established in their vicinity.

The distinctive characters of regeneration and of suppuration, destructive inflammation, will be considered under the head of Terminations or Issues.

Both the causes and the products of inflammation constitute very important grounds of distinction, and a rigid discrimination is necessary between inflammations from external, and inflammations from internal causes. To the former class belong not alone the inflammations locally engendered by direct external influences, but also those awakened in remote but sympathetically allied formations, through the mediation of the nerves. To the latter class belong those hyperaemiae and stases based upon a greatly overwrought condition of the nervous centres, be it irritation or paralysis, and more particularly inflammations arising out of a pre-existent dyscrasial or humoral element.