NECROSIS. 



275 



atheromatous vessels. In the so-called neuropathic necroses 

 occurring in diseases of the nervous system an important part 

 is undoubtedly played by trauma and circulatory disturbances. 

 Under the microscope it is noted that the cell-nucleus loses 

 its affinity for nuclear dyes " chromolysis" or the chroma- 

 toplastic substances are broken up into fragments " karyo- 

 lysis" and the nucleus finally disintegrates and disappears, the 

 cell-protoplasm becoming homogeneous in appearance. There 



FIG. 111. 



Fat-necrosis. The abrupt transition from the healthy cells on the left to the ne- 

 crosed cells on the right is well marked. The contents of the affected cells are 

 finely granular. (From a specimen by Dr. Rolleston.) 



is always more or less inflammatory reaction in the surround- 

 ing tissues. Complete regeneration or cicatrization, calcifica- 

 tion, or cystic formation may follow. 



Several varieties of necrosis are usually described : Coagala- 

 tion-necrosis is a variety in which there is coagulation of the 

 fluids normally present lymph or of inflammatory exudates, 

 and the cellular protoplasm of the tissue. Fibrin is deposited 

 in the form of granules or fine fibrillae ; the cells lose their 

 nuclei and their protoplasm becomes granular. The necessary 

 ferment to produce this coagulation is derived either from the 

 degenerating and disintegrating cells or from bacterial prod- 



