4. The step to which stasis ultimately leads is genuine effusion, that is, the exudation of blood-plasma, a fluid holding in solution fibrin, albumen, and salts. It is thrown out into parenchymata, filling up their interstices to a various extent, either as a fluid, or as a more or less solidified product. Or, again, it is partially, or, it may be, wholly expended upon the free surfaces of natural cavities and canals, or of such as have arisen out of the previous transudation of serum, for example, in vesication of the epidermis, or in antecedent suppuration of textures, - in abscess cavities.

With exudation, the inflammatory process is to be looked upon as closed. It is immediately followed by an endosmotic current of the serous portion of the effusion, causing the blood-corpuscles to float in a thinner medium, to exchange their now flattened for a more spherical shape, to become separated, to part with a portion of their pigment, and finally, by dint of a returning resilience in the bloodvessels, to move, conjointly with the aforesaid form-elements, onward again in the circulating stream.

We have now furnished the reader with a substantial description of the several acts which make up the process of inflammation. We shall further endeavor to show how these may be reconciled with the present standard of pathological science.

1. The first experimental phenomenon adverted to, namely, contraction of the capillaries, with acceleration of the blood-stream, has been stated to be inconstant, and indeed absent altogether, when potent stimuli have been used in the first instance. Where it does occur, it is to be regarded as a vital phenomenon. The contraction of the bloodvessels is moreover independent of any simultaneous collapse of the parenchyma, like that produced, for example, by the action of cold.

2. The dilatation of bloodvessels and the retardment of the bloodstream are, on the other hand, constant and essential. The very fact of their being so commonly the primitive phenomena, or at any rate of their succeeding very rapidly to a previous contraction, refutes the notion of their consisting in a secondary relaxation, resulting from exhaustion. With these, and with the subsequent stasis, the theories of inflammation hitherto advanced are mainly concerned.

Henle reduces these to an attraction-theory, and to a neuropatho-logical theory.

(a.) The attraction-theory refers the essential phenomena of inflammation to an augmented affinity between the parenchyma and the blood, and especially to an anormal attraction of the blood, and of the blood-corpuscles in particular, by the affected parenchyma. It assumes the retardation of the blood-stream, and the crowding together of the blood-disks to be the primary - the dilatation of the capillaries a secondary phenomenon. It explains even the stasis as a continued increment of that attraction.

The augmented attraction is effected through the intervention of the nerves, and either by direct influence upon the peripheral nerves, or else by reflection from the centres of the nervous system.

The attraction-theory carries the problem of congestion and stasis a step farther, without solving it. Together with its common attribute, namely, an increased afflux of blood to the diseased part, as due to a dilatation, and to a more frequent contraction of the afferent artery, it has been met by many valid objections. It is only the stasis and inflammation engendered by a pre-existent dyscrasis that can, provided the attraction be not limited to the blood-corpuscles, but embrace the diseased plasma, warrant the conclusion of a preternaturally strong affinity between blood and parenchyma. There would be some analogy between such a localization of general disease, and the indwelling relation of secreting parenchymata to certain normal or anomalous ingredients of the blood. But these inflammations, like the rest, are aptly expounded in the neuropathological theory.

The neuropathological theory, on the contrary, assigns to the nerves an important part, and ascribes the accumulation of the blood to the dilatation of the bloodvessels, this being set down as the primary - that as the consecutive phenomenon.

The dilatation of the vessels is the consequence of paralysis of the nerves. Respecting the cause and the conditions of this paralysis, there exist two different opinions.

According to Henle, an antagonistic relation prevails between the states of irritation of the sensitive nerves, and of the nerves of the bloodvessels: a high degree of inflammatory irritation in a sensitive nerve producing a state of depression - in a word, paralysis of the implicated bloodvessel nerves.

According to Stilling, the sensitive and the bloodvessel nerves bear, on the contrary, a direct sympathetic relation to each other. He assumes a continual reflex action to be kept up by the sensitive, upon the bloodvessel nerves, whereby the tone of the latter is sustained. With paralysis of the former, the tone of the latter is destroyed; whereas by excitation of the former their reflective power is augmented, and the tone of the latter thereby raised. In accordance with this reciprocity, two different kinds of inflammation are made out.

Griesinger was led to the adoption of a similar view, imagining pain to result from a qualitative disturbance of the texture of the nerve.

Against this hypothesis it is to be objected that a continued reflex action of the nerves of sensation upon those of the bloodvessels as a necessary condition for the undisturbed function of those vessels is not proved; and that the assumption of two different characters of inflammation, involves both a contradition in adjecto, and a disregard of the results of observation. An inflammation with augmented tone of the bloodvessels cannot exist, and this admitted, inflammation with and through paralysis (diminished tone), must invariably ensue from influences paralyzing to the sensitive nerves. This is, however, opposed to daily experience.