256 DISEASES OF THE BRAIN. 



small extravasations of blood. The swelling of the inflamed parts may 

 be recognized by the surface of the brain on the affected side appear- 

 ing smooth, just as in apoplectic effusions, and the brain itself being 

 anaemic from encroachment on the cranial cavity. On incision also 

 the diseased portion not unfrequently rises above the level of the in- 

 cised surface. After long existence, the relaxation of tissue gets the 

 upper hand, and a red pulp results, which gradually acquires a rusty- 

 brown or yellow color, from change of the hasmatin, or when there is a 

 slight admixture of blood it "becomes grayish. This pulp, which may 

 be washed off by a slight stream of water, consists of remains of nerve- 

 filaments, blood-corpuscles, granular cells, and fine granular exudations 

 or masses of detritus. The subsequent changes in the inflamed parts, 

 which are usually called the results of inflammation, vary. Occasion- 

 ally, in the vicinity of the inflammation, there is a new formation of 

 connective tissue, which is also continued through the inflamed spot 

 as a delicate network ; the contents of the abscess are absorbed, and 

 there remains a cavity, filled with a chalky milky fluid, the " cellular 

 infiltration" of Durand-Fardel^ previously mentioned in apoplexy. 

 In some cases, especially when these cysts lie near the surface of the 

 brain, their walls gradually approach each other, while the contents 

 disappear, and in place of the abscess there is formed a cicatrix, at first 

 pale red and vascular, subsequently white and callous. When ence- 

 phalitis terminates in suppuration, the appearances are different. Re- 

 cent abscesses of the brain form irregular round cavities filled with 

 yellow or gray, occasionally also reddish, thick fluid ; their walls con- 

 sist of ragged masses infiltrated with pus. In the immediate vicinity 

 of the abscess we usually find inflammatory softening ; farther off there 

 is oedema of the brain-substance. Such abscesses increase till they 

 break into a ventricle, or reach the meninges ; or, if extensive menin- 

 gitis do not occur in the latter case, the ulceration extends to the cere- 

 bral membranes and the skull, and finally the pus may perforate out- 

 wardly or into neighboring cavities, especially into the cavity of the 

 tympanum. If the cerebral abscess be capsulated by new formations 

 of connective tissue in its wall, it has a more regular form and smooth 

 walls. If it has lasted a long time, we occasionally find the capsule 

 much denser, and the contents thickened by reabsorption of the fluid 

 part, and changed to a cheesy chalky mass. 



SYMPTOMS AND COURSE. Like the symptoms of cerebral haemor- 

 rhage and of partial necrosis, those of encephalitis are partly the im- 

 mediate result of destruction of the portion of brain affected, and 

 partly the result of disturbances of circulation in the brain, especially 

 in the vicinity of the seat of inflammation. 



Since large portions of the brain may be destroyed without caus- 



