Even very extensive inflammations terminate in this manner. There is no question that the cavity, just spoken of, may gradually diminish, and at length close, like the apoplectic cyst, - for which it is not unfre-quently mistaken. The diagnosis between them (which I will mention at once) is often very difficult, and sometimes cannot be made without referring to the early symptoms of the disease. The difficulty arises, on the one hand, from the fact, that high degrees of inflammation are, at first, always complicated with hemorrhage; and, on the other, that inflammation often supervenes upon hemorrhage. The apoplectic cyst generally has its well-known rusty-brown or yellowish lining; but it loses, in the course of time, nearly all its coloring matter. The cavity left after inflammation usually has no such lining; but sometimes, when considerable hemorrhages have taken place, the inner membrane of this cavity also is colored with rusty brown, or yeast-like, yellow pigment. If a more intense inflammation should have occurred around the seat of hemorrhage in the brain, and produced the so-called cellular infiltration and its consequent cavities, the apoplectic cyst can usually be distinguished in the midst of them, by its colored lining. It may, however, have almost lost this lining, or the other surrounding cavities may also be colored with a coating of pigment.

c. Inflammation may terminate in induration, sclerosis. At the seat of inflammation, there remains a white or dirty white, rounded, elongated, or irregularly branched cicatrix; or, in a few cases, a callous, grayish, semitransparent substance. The cicatrices which are occasionally found scattered in considerable numbers throughout the brain, in persons subject to convulsions and epilepsy, are most probably examples of the former kind. They consist of a compact mass of elementary molecules, traversed by a few delicate fibrils like cellular tissue. The termination in induration combined with a growth of fibroid tissue, and condensation, may be noticed around tubercle, abscesses, etc.

d. When the process terminates in suppuration and abscess, the products of the inflammation become converted into pus; and the other tissues involved in its area, the extravasated blood and cerebral substance, with its vessels, perish (necrosiren) and disappear.

The recent abscess is a rounded cavity, irregularly hollowed out of the parenchyma of the brain. Its walls are composed of suppurating cerebral tissue, sloughing shreds of which, soaked in pus, hang inward into the cavity, while all around the brain is in a state of inflammation, - of red softening. The more distant cerebral substance is oedematous; and very often the part encompassing the area of red inflammation, is found in a state of yellow softening, which has occasioned death. The diseased division of the brain, and sometimes the entire organ, is swollen, anaemic, fluctuating, etc, in degrees proportioned to the size of the inflamed spot, and the activity of the processes going on around it. The pus contained in the abscess is thick and greenish, and has an extremely fetid phosphorescent odor.

By continued inflammation and suppuration, the abscess advances beyond the bounds of the original inflammation. Sometimes it enlarges uniformly on all sides; but it generally does so in one direction only, and in the form of a sinus.

When an abscess thus enlarges, and the process of ulcerative inflammation extends to other structures, such as the membranes of the brain, the cranium, etc, an outlet may be formed, and the matter discharged. It is, however, a necessary condition, that the inflammation of the inner membranes be limited, and do not spread out into an extensive meningitis. Such outlets may be formed at various parts of the skull, and the matter be discharged either directly outwards, or into natural cavities and canals which convey it away. In this manner pus is discharged from an abscess of the brain, through the cribriform plate of the ethmoid bone into the labyrinth and cavities of the nose, or through the tympanum and meatus auditorius externus. In the latter case, the roof of the tympanum or the wall of the mastoid cells is destroyed by caries, and the matter finds its way into the tympanum; from whence, after ulceration of the membrana tympani, it is discharged. Such a purulent discharge bears the name of otorrhoea cerebralis, inasmuch as the matter, though coming out at the ear, proceeds, in part at least, and for some time, from the brain. Albers considers that the priority of the affections of the brain and ear may be reversed, and sometimes -one, sometimes the other, may be the original disease: while, in a third case, both may arise together, from a common cause.

The rupture of an abscess of the brain into the ventricles is always rapidly fatal.

Although abscess in the brain is usually fatal, yet patients very often live on with it for a considerable period, and sometimes without presenting any clear evidence of its existence. In such a case the abscess has become encysted, and is even capable of being completely healed.

The abscess becomes enclosed in a firm capsule, by the conversion of the granulating layer on its inner surface into a dense, cellulo-fibrous (fibroid) membrane, while the adjoining layer of cerebral substance becomes condensed, and like a cicatrix.

The inflammatory process may be renewed in the walls of an encysted abscess; or oedema, or yellow softening, may take place in its neighborhood, and, in either way, death very frequently ensues. But as I have said, the abscess may heal. The pus is then partly absorbed, the remainder of it becomes inspissated, and forms a chalky residuum; and the capsule enclosing it contracts equally, and at length altogether wastes.

Every inflammation of the brain may terminate in suppuration; but it is more especially those inflammations which are produced by wounds, and concussion of the brain, that take this course.