DEGENERATIONS AND INFILTRATIONS. 



281 



The cells in the epithelial pearls of epitheliomata often undergo 

 these degenerative changes, producing large masses of eleidin or 

 keratin. The change in these cases may be considered as due to 

 a retention of this normal tendency by the epidermal epithelium 

 under the abnormal conditions in which it is placed in the tumor. 

 In those cases of metaplasia in which columnar epithelium becomes 

 converted into the stratified variety the susceptibility to keratoid 

 degeneration is an acquired character, columnar epithelium under 

 normal conditions never suffering this change. 



10. Amyloid Infiltration. The change in the tissues known by 

 this name, or that of amyloid degeneration, has many resemblances 

 to hyaline degeneration (or infiltration). Amyloid differs, however, 

 from the hyaline substances in being recognizable by means of a 

 number of characteristic reactions, although they vary considerably 



FIG. 253. 



Amyloid infiltration in the liver. (Thoma.) a, lumen of an intralobular capillary, sur- 

 rounded by the endothelial wall of the vessel ; 6, amyloid substance immediately 

 beneath the endothelium ; c, epithelial cells of the hepatic parenchyma, some of which 

 show a fatty infiltration. 



in sharpness in different cases, and give rise to the suspicion that 

 the amyloid substance is not always of constant chemical composi- 

 tion, or that it may be transformed into other substances of similar 

 physical and optical properties. 



Amyloid is a nitrogenous material, which is stained a dark brown 



