Nervous and mental diseases . cur before the ageof twenty. The tumors vary in size from a pea to a hens egg, or evena larger size, and in number from one to a score. Sarcomatous growths are next in frequency. Usually they presentthe distinctive and important character of being more or less encapsu-lated and sharply separated from the brain-tissue, from which they can,therefore, if accessible, be easily enucleated. As a rule, they are out-growths of the cranial dura or periosteum, and the majority of them aresituated in the basilar region, involving the brain-axis. In compara-tively rare instan
Nervous and mental diseases . cur before the ageof twenty. The tumors vary in size from a pea to a hens egg, or evena larger size, and in number from one to a score. Sarcomatous growths are next in frequency. Usually they presentthe distinctive and important character of being more or less encapsu-lated and sharply separated from the brain-tissue, from which they can,therefore, if accessible, be easily enucleated. As a rule, they are out-growths of the cranial dura or periosteum, and the majority of them aresituated in the basilar region, involving the brain-axis. In compara-tively rare instances they infiltrate the brain-tissue, or, arising at thevertex, spread out broadly. They are of rapid growth, and in a givencase furnish pronounced, persistent, and uniform symptoms. Theypresent the variations of cellular elements that mark sarcomata else-where. As a rule, they are single. Glioma is peculiar to nervous structures. It arises from the neu-roglia and finds its most usual seat in the brain, though it may occur in. Fig. 96.—Sarcoma of right temporosphenoidal lobe. A, Basilar surface ; B, transverse section (Dr. W. A. Jones). the spinal cord or retina. It presents a reddish, vascular color and asoft consistency quite like that of the brain-substance. Glioma is emi-nently an infiltrating and a destructive growth. Its outlines are difficultto determine. Owing to its strangulating effect, the center of a glioma isfrequently filled with softened detritus and fatty-degeneration products,which may become fluid and the growth thereby cystic. Many allegedlocal brain-hypertrophies have been gliomatous infiltration in fact,and the microscopic examination of cyst-walls has alone discoveredthe true nature of the lesion in other instances. The favorite locationof glioma is the white substance near the cortex, and it may infiltratelarge areas, even the greater part of a hemisphere. Ordinarily it is consistency they are soft, often highly vascular, and may in some17 258
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