_Tuberculous masses_ occur most frequently in children and adolescents, and other signs of tuberculosis are usually present. The cerebellum is a common seat of these tumours, and they are often multiple. Their growth may be rapid at first, and then become arrested for a time. Spasmodic growth of a tumour strongly suggests its tuberculous nature, and superadded signs of basal meningitis confirm the diagnosis. _Endothelioma_ grows from the dura mater, and in so far as it is a well-defined and non-infiltrating growth it lends itself to removal by operation. Unfortunately, however, it is usually located at the base of the brain and is not readily accessible. _Glioma_ is usually met with in the young; it tends to grow slowly at first, but may take on a rapid growth at any time, and hæmorrhage is liable to occur into the substance of the tumour, causing a sudden aggravation of the symptoms. _Sarcoma_ occurs between puberty and middle life; it grows slowly, and compresses rather than destroys the brain tissue. It is sharply defined from the surrounding cerebral tissue, and is therefore more favourable for operation than glioma. The _prognosis_ is grave in all forms of brain tumour. Even in syphilitic growths, although the more urgent symptoms may be ameliorated by the use of drugs, recurrence is liable to occur, and the structural changes induced in the cerebral tissue, and the contraction of the cicatrix which results, may permanently interfere with the functions of the brain, or may induce Jacksonian epilepsy. Tuberculous tumours also may become arrested, and may cease for a time to cause symptoms, but permanent cure is extremely rare. We have known a sarcoma to recur as late as five years after removal. Death sometimes occurs suddenly from hæmorrhage, from acute œdema, or from implication of vital centres. _Treatment._--It is to be borne in mind that gummatous growths in the brain are seldom influenced to any extent by anti-syphilitic remedies, and time should not be wasted in trying this form of treatment. The question of removal by operation arises in cases in which there is reason to believe that the tumour is situated near the surface of the brain and that it is circumscribed and of moderate size. Unfortunately it is only in a small proportion of cases that these conditions are present and can be recognised before opening the skull. In many cases in which there is no hope of being able to remove the tumour, it is advisable to relieve symptoms due to excessive intra-cranial tension, such as blindness, severe headache, and persistent vomiting, by performing a "decompression operation" (_Operative Surgery_, p. 108). The relief that follows such operations is often remarkable. Lumbar puncture, frequently repeated, has also been practised for the relief of tension in inoperable cases, but it is not free of danger and is not to be looked upon as a substitute for a decompression operation.