Anmmia of the bmin, according to my ob servation, is of two kinds, general and partial. In the former, pallor prevails throughout the brain. This is met with, as before mentioned, in ill-nourished children ; and it is also present to a remarkable degree in persons, house painters and others, who have largely imbibed the poison of lead, as if the presence of that poison interfered greatly with the process of hmmatosis. Partial anwmia is where the defi ciency of blood is observed chiefly in the grey matter. I have frequently seen the grey matter of the convolutions perfectly bloodless, and the white matter of the hemisphere covered with bloody points of congested veins. This is the condition generally met with after death from rheumatic or gouty delirium.
When the brain is very anwmic a consider able quantity of fluid is generally found beneath the atachnoid membrane, with or without a small quantity in the ventricles ; or more rarely, a good deal of fluid in the ventricles, with little or no subarachnoid fluid.
Of cerebral hemorrhage. — Effused blood from one or more ruptured bloodvessels is found upon the surface, in the substance, or in the ventricles of the brain. Effusion of blood in any or all of these situations constitutes the most common form of cerebral apoplexy.
The blood is sometimes effused simply upon the surface of the bmin; it is diffused beneath the arachnoid membrane, and even under the pia mater, raising up that membrane and sepa rating it from its connection with the cerebral substance. Not unfrequently such a diffusion of blood beneath the pia mater is connected with an internal extravasation which has made its way to the surface either through broken down cerebral substance or from the ventricles.
A recent apoplexy in the substance of the brain is no more than a dark clot of blood, like a mass of black currant jelly, filling a cavity which it bas formed for itself in the cerebral substance. Such is the appearance when the examination has been made a few hours or even a few days after the apoplectic fit. If the patient survive this period, we find evidence of changes in the clot and in the surrounding cerebral substance. These changes vary ac cording to the condition of the brain prior to the apoplectic effusion.
If the brain has been quite healthy up to the occurrence of the rupture, a condition which is extremely mre, then the changes towards cica trization take place quickly; the serum of the clot becomes absorbed ; the torn brain-substance around the clot contracts; the solid matter of the clot assumes a reddish instead of a black hue; it gradually diminishes in quantity, and the bmin-substance, not contracting to the same extent as the clot has done, a cavity reniains, which contains serum, and more or less of the remnant of the clot. The cerebral substance
forming the wall of this cavity has a yellowish colour, somewhat of the same hue as that which is seen after extmvasated blood in the subcuta neous tissue, and it is denser than is natural. After the lapse of more time the cavity con tracts, and nothing remains but a spot of dis coloured and somewhat indurated cerebral substance. When the apoplectic clot has been of large size, and has occasioned an e.xtensive solution of continuity, the contmction of the surrounding substance is not sufficient to obli terate the cavity, which in such instances is occupied by a soft, loose, areolar tissue, infil trated with fluid. In other cases the cavity is lined by a distinct membrane and is filled with fluid, forming a true cyst. Cruveilhier affirms that the most frequent sequel to the apoplectic clot ia the indumted and discoloured spot of cerebral substance; next in frequency is the cavity with the loose areolar tissue ; and last, the cavity lined by a membrane or the serous cyst.
The morbid condition which surrounds the apoplectic effusion is generally that of colour less softening. This state doubtless precedes the rupture which gave rise to the hemorrhage. Sometimes, however, red softening extends around it more or less; this generally follows the effusion. The existence of either of these morbid states is very unfavourable to the con traction and cicatrisation of the apoplectic cyst.
It frequently happens that in the cerebral substance around an apoplectic clot we find very numerous small points of effused blood, sometimes accompanied by minute streaks fol lowing the direction of the cerebral fibres. This constitutes what is called capillary apo plexy. Sometimes this is the only marked appearance present, and no large clot has been formed. This occurs not uncommonly in a plexy affecting the medulla oblongata and mesocephale. When many such minute sions take place very near to each other, i easy to understand how by their coalition may form a large apoplectic clot; and i most probable that large effusions gene arise in this way, not from the rupture of or even of a few vessels, but from tha numerous minute ones.