THE NERVOUS SYSTEM. 779 



epeudyma. Tuberculous inflammation of the ependynia is, as above 

 mentioned, a not infrequent accompaniment of tuberculous meningitis. 



Chronic Ependymitis. This lesion, which is much more common than 

 simple acute inflammation of the ependyma, occurs under a variety of 

 conditions, and its nature and causation are in general very obscure. 

 The ependyma is thicker, whiter, and more opaque than normal, so that 

 the vessels may be nearly or quite invisible. The thickenings may oc 



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FIG. 512. ACUTE EPKXDYMITIS. 



Showing replacement of the epithelium of the ventricle by inflammatory exudate ; collections of pus cells 

 near the epithelium and about the adjacent small blood-vessels. 



cur in patches or diffusely, and the surface of the ependyma may be 

 smooth, or roughened and granular. On microscopical examination the 

 surface of the ependynia may be covered with the usual epithelium, but 

 the new connective tissue which forms beneath it often raises it up in 

 places, causing the roughness of the surface. The new tissue is usually 

 rather loose in texture and may contain many small spheroidal cells ; but 

 it may be dense in texture and contain few cells. The brain tissue be- 

 neath the thickened ependyma may be softened or infiltrated with cells. 

 The sides of the ventricles may be grown together in places by the adhe- 

 sion of the thickened and roughened epeudyma. The ventricles usually 

 contain more serum than normal, and sometimes this accumulation is 

 so great as to cause an enormous dilatation of them. While these are 

 in general the prominent lesions in chronic inflammation of the epen : 

 dyma, the cases vary greatly in the degree to which these changes are 

 developed. 



The accumulation of fluid and the dilatation of the ventricles being 

 the most marked feature in all this class of lesions, they are often called 

 chronic hydrocephalus, but in many cases we have no evidence that the 



