PSAMMOMATA (GRITTY TUMORS) OF THE BRAIN. 



As alread}' noted these sand}' tumors are often the advanced 

 stage of cholesteatoniata, the abundance of the phosphate of lime 

 leading to its precipitation in the neoplasm. The same cretaceous 

 deposit often takes place in old standing tumors of other kinds, as 

 in melanoma, and fibroma so that the sandy neoplasm may be 

 looked upon as a calcareous degeneration of various forms of 

 intracranial tumors. The same tendency to calcareous deposit is 

 seen in the tuber cinereum (pineal body) of the healthy brain 

 which has taken its name from the contained gritty matter. This 

 tendency to the precipitation of earthy salts may be further recog- 

 nized in the osteid tumors which occasionally grow from the dura 

 mater. 



The gritty tumors are especially found in the older horses in 

 which the tendency' is greatest to extension of ossification and 

 calcic degenerations. 



lyike other tumors tliese may attain a considerable size before 

 the}' give rise to any very appreciable symptoms, but having 

 attained a given development — often the size of a walnut, they 

 become the occasion of nervous irritation, delirium and disorder, 

 as indicated under encephalic hyperaemia and inflammation, 

 cholesteatoniata, etc. There maj', however, be drowsiness, stupor, 

 coma, or paralysis as the exclusive symptom, or there may be 

 .spasms and convulsions. 



MYXOMA OF THE BRAIN. 



Myxoma is a tumor in which mucoid elements or a gelatinoid 

 degeneration and infiltration containing mucin is a prominent 

 feature. The vnicoiis tissue which constitutes the tumor may differ 

 little from ordinary connective tissue except that the intercellular 

 .spaces contain mucin. Histologically the tissue con.sists of cells 

 embedded in a homogeneous matrix. The cells may be of va- 

 rious forms, round, (in recent formations) and spindle-shaped or 

 star-shaped, but especially the latter, in the older. When incised 

 a fluid containing mucus escapes in greater or less abundance. 



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