DEGENERATIONS AND INFILTRATIONS. 279 



nephritis appears to be colloid elaborated by the cells lining the 

 renal tubules, but those casts may not always owe their origin to this 

 form of degeneration. 



FIG. 251. 



FIG. 252. 



. f . 







Hyaline degeneration. (Ernst.) 



Fig. 251. Hyaline degeneration of cells in the choroid plexus. In this case the hyaline 

 material appears to be derived from the cytoplasm of the cells, thepi'ocess constituting 

 a true degeneration. Transitional conditions from the unchanged cells to masses of 

 hyaline without traces of cellular structure are found in the specimen. 



Fig. 252. Hyaline degeneration of the capillary walls in a psammoma of the dura mater. 

 Here the endothelial lining of the capillaries is intact, the hyaline material being out- 

 side of it. This disposition of the hyaline would lead to the inference that in this case 

 it was the result of infiltration. 



It is probable that the composition of colloid is not always the 

 same. It is identified by the facts that it is a clear, structureless 

 substance, derived from cells and not presenting the characteristics 

 of mucus. The causes and mode of its production are unknown. 



