TUB MICROSCOPE IN PATHOLOGY. 



235 



Softening of the brain, as it is termed, is largely due to 

 fatty degeneration. Whatever interferes with nutrition, 

 by preventing a proper supply of blood, will produce fatty 

 degeneration and softening. Acute cases may be pro- 

 duced by embolism or thrombosis. White softening is 

 generally a chronic condition of old age, and owes its 



FIG. 187. 



From the inner surface of a larger emphysema vesicle. Fatty remains of the lung- 

 tissue, containing elastic fibres, smooth muscular fibres, and covered with fatty degen- 

 erated epithelia. 1-500. After RINDFLEISCH. 



color to the gradual diminution of blood-supply. Yellow 

 and red softening depend on larger proportions of blood- 

 pigments. A vertical section of a specimen of yellow 

 softening shows accumulations of fatty granules between 

 the nerve-fibres, and their formation into larger granular 

 corpuscles (Fig. 188). 



2. Mucoid Degeneration. 



This is a transformation of albuminoid tissues into 

 mucin, a material of a soft jellylike consistence. This is 



