The temperature is high and rigors are frequent. The pulse is small and rapid, the respiration increased in frequency, irregular, and often partaking of the Cheyne-Stokes type. The face is livid, the skin hot and burning. Vaso-motor disturbance is evidenced by profuse sweating and well-marked _tache cérébrale_. =Prognosis and treatment.= The prognosis is almost hopeless unless radical measures are adopted in the early stages. The scalp-wound should be enlarged and comminuted fragments of bone removed, or the skull trephined over the region of the suspected abscess. The lacerated dura mater is freely opened up and the surface of the brain exposed. Purulent material is gently removed, and the wound closed in such a manner as to allow of free drainage. Even under the most favourable local conditions the prognosis is bad. =Chronic abscess.= As a preliminary statement it must be pointed out that breaking down new growths, softening gummata, caseating tuberculous masses, actinomycotic and hydatid cysts, are regarded in the light of tumour formation and are discussed elsewhere. Of 52 cases of brain abscess admitted of recent years into St. Bartholomew’s Hospital, 41 partook of the chronic type, 30 being dependent on otitic disease, 3 on frontal sinus suppuration, 5 resulting from lung disease, and 2 of uncertain origin. The 11 acute cases were either traumatic or pyæmic. From these and other statistics it may be regarded as generally accepted that the majority of brain abscesses are secondary to chronic disease of neighbouring bone, and more especially middle ear disease. This being the case, it might naturally be inferred--on anatomical grounds--that the temporo-sphenoidal lobe of the cerebrum and the cerebellum are more liable to infection than any other part of the brain. From 100 cases treated at my hospital the temporo-sphenoidal lobe and cerebellum were involved in the proportion of about 2 to 1. Körner,[52] reporting on another 100 cases, gives the following data:-- Abscess of the cerebrum 62 cases „ „ cerebellum 32 „ „ in both situations 6 „ Hunter Tod,[53] reporting on 100 cases treated at the London Hospital, found that in children under 10 years of age temporo-sphenoidal abscess occurred in 87 per cent. cases, and cerebellar in 13 per cent., whereas in adults cerebral abscess occurred in 65 per cent. and cerebellar in 35 per cent. The development of temporo-sphenoidal and cerebellar abscesses in the same case was observed in 5 per cent. cases. =Pathology.= Insomuch as chronic middle ear disease forms the main predisposing factor in the development of abscess of the brain, the pathology of brain abscess in general may be considered by discussing the main features peculiar to otitic abscess in particular.