Such are the chief functional disturbances of the brain met with in rheumatic fever, and the post-mortem examination reveals in them either quite normal naked-eye appearances, or more frequently, especially in rapidly fatal cases, general congestion of the pia mater, and to a less degree of the cerebral substance, or in more protracted cases a greater or less increase of transparent or opalescent serum in the subarachnoid space and ventricles. The serum may be slightly or deeply tinged with blood. If the serous or sero-sanguinolent effusion be considerable, the encephalic mass or portions of it may be anæmic. But besides these conditions, which are also commonly observed in many other febrile diseases, and which are probably only concomitants of the functional disturbance arising in the advanced stage of acute articular rheumatism, certain organic affections of the nervous centres or their membranes occasionally occur in this disease, and are plainly the cause of the cerebral disturbance observed during life. Cerebral meningitis, although very rare as a complication of acute articular rheumatism, except in certain hot climates, like that of Turkey,[88] does occur, and lymph or pus is found, usually over the convexity of the brain, but sometimes at the base and down the cord.[89] The symptoms of rheumatic cerebral meningitis are very like those of rheumatic delirium; vomiting, and even, but less frequently, pain in the head, may be absent, while hyperpyrexia may coexist (Foster's case), although not necessarily present. Should the pulse from being frequent become slow and irregular, and any paralytic symptoms ensue, meningitis may be suspected. In some of these cases the meningitis is a consequence of ulcerative endocarditis and embolism of the cerebral vessels,[90] but in others it obtains without endocarditis or any purulent formation elsewhere than in the meninges, as there is probably a true rheumatic localization like pericarditis. The articular inflammation may continue after the invasion of the meningitis, or the latter may promptly follow the disappearance of the former, as though a metastasis of morbid action had taken place.[91] In many instances, according to Ollivier, Ranvier, Behier, and others, although the macroscopic signs of meningitis are absent, the microscope detects proof of its presence in the existence of an increased number of vessels, fatty granulations on their walls, proliferation of nuclei and capillary extravasations--histological conditions identical with those found in the mild degrees of rheumatic inflammation of the joints. [Footnote 88: Senator, in _Ziemssen_, xvi. 50.] [Footnote 89: Watson's _Prac. Physic_, 1872, Am. ed. vii. 335; Fyfe, _Med. Gazette_, vol. xxix. 703; Fuller, _lib. cit._, 302; Leudet, _Clin. Médicale_, 139; Dowse, _London Lancet_, ii. 1872, 9; Foster, _ib._, ii. 1868, 115; Hicks, _New York Medical Record_, Nov., 1878, 404.]