This pathological process is of paramount interest, not only on account of its great frequency, and of the great variety of external causes by which it is called forth, but also as being that in which most, and in a certain sense all, general diseases become localized. It is a process which leads incontinently to the most various and most extensive new growths, and associates itself, equally often, to other anomalous formative efforts. In fine, it is a process which, on the one hand productive, on the other hand frequently proves destructive of both normal and anomalous formations.

The inflammatory process is capable of being experimentally called forth and observed, in all its phases, in transparent textures. Thus studied, it has furnished the groundwork for the most varied interpretations, but, at the same time, for researches respecting other exudatory processes. Nor have these experiments failed in a certain measure to elucidate the connection that prevails between blastema and the endogenous formative processes carried on in the blood itself.

We seek not to deprive this process of its time-honored name, inflammation, because it has become naturalized in science beyond all others. It is applicable enough, if in using it we simply dismiss the theories which first led to its adoption. It comprehends the entire process, and the efforts made to designate the latter differently have utterly failed. Andral's hyperaemia, and Eisenmann's stasis have not advanced the subject by a single step.

It is impossible to define inflammation suitably, owing, on the one side, to our imperfect knowledge of its proximate causes; and, on the other, to the complex nature of its consecutive phenomena. These latter, variously modified in type, point to processes equally varied, whilst they at the same time furnish the most striking analogies with other processes which issue in exudation (production of blastema).

Let us now proceed to a descriptive examination of the phenomena which constitute so many stages of the process, a due regard being had to the results of experiment, that is, to the observation of the inflammatory process as artificially called forth in animals. And in this description, together with the analytical remarks annexed to it, we will take for our basis the so-called pure, legitimate, inflammation, which yields essentially a coagulable, fibrinous, plastic product, as developed in sound organisms without the co-operation of a pre-existent dyscrasis, and simply as a consequence of moderate local stimulation; such being the most marked of any in its manifestations and stages.

The phenomena of the inflammatory process present the following sequence.

1. The moderate influence of mechanical or chemical stimuli is followed by contraction of the capillaries, and simultaneous quickening of the blood-stream through them. This phenomenon may be wanting as an effect of most causes of inflammation in the human species; and even in experiments upon animals it is either transitory or entirely absent if the stimuli applied be potent.

Contraction of the vessels is succeeded sooner or later by -

2. Dilatation of the capillaries, if this be not, indeed, the very first cognizable phenomenon. Unlike contraction, it is invariably present, readily seen both in the living animal and in the dead subject, as is, in like manner, the simultaneous loading of the vessels with an increase of blood. It determines capillary injection, and therefore the redness of injection proper to inflamed textures.

This dilatation of the vessels is attended by a retarding of the bloodstream, which sooner or later, although not always visibly, merges in an oscillating movement of the blood in the capillaries. The contained blood-columns move forward and backward by turns, the onward movement, however, predominating. The blood-corpuscles begin to adhere to one another, like rolls of coins, the outer linear layer of plasma (the lymph space) within the vessel still remaining unchanged.

This twofold proceeding establishes the stage of congestion.

3. Hereupon ensues, sometimes so rapidly as to prevent the retardment of the blood-stream and its oscillation from being noticed, stagnation of the blood-stream, - stasis. The bloodvessels are completely filled up with blood-corpuscles, so that the transparent, so termed, lymph space, near the circumference of the vessel and before occupied by plasma, has vanished. Meanwhile the blood-corpuscles have assumed greater intensity of color, have become flattened, contracted, and firmly glued to each other, and to the vessel's walls, so as to form a homogeneous red mass, with irregular translucent intervals.

The nuclei and nucleated cells (so-called lymph-globules and colorless blood-corpuscles) have increased in number to an extraordinary extent, often adhering together in groups connected by delicate transparent coagula, and forming either thus, or singly, the aforesaid translucent intervals. The blood has assumed a dark tile-colored aspect, verging upon cherry-red.

In the preceding stage (see hyperaemia), as well as in this, two notable phenomena are witnessed, namely:

(A.) Laceration Of Bloodvessels

Laceration Of Bloodvessels, and extravasation into the textures, or into the free spaces, - lung-cells; muco-membranous cavities and canals; serous sacs. The hemorrhage is frequent and considerable, proportionately to the degree of congestion and stasis, and also to the delicacy and the textural looseness of the diseased part. For the most part it takes the form of capillary apoplexy, and only in very delicate normal and anomalous textures, as, for example, the brain or encepha-loid cancer, the form of the isolated clot.

(B.) Transudation Of Blood-Serum

Transudation Of Blood-Serum through the thinned bloodvessel walls into the parenchyma, and from membranous expansions into the cavities and canals of which they form the lining. This implies, in the parenchymata, pervading moisture, - in expansive structures, diffuse exudation or circumscribed accumulations beneath the epidermis, - for example, in burns, in vesication artificially called forth, in erysipelas, and the like. The exuded serum resembles essentially blood-serum, only that it is, for the most part, less rich in albumen. This phenomenon often merges at once in the exudatory process next succeeding, the two acts being simultaneous.