DEGENERATIONS AND INFILTRATIONS. 



283 



also liable to calcareous infiltration. That infiltration appears, 

 then, to be always secondary to some morbid process lowering the 

 vitality of the tissues. 



Calcareous infiltration may serve as a type of infiltrations with 

 other materials, such as urates, and of the formation of concretions ; 

 for example, gall-stones. These and 

 other concretions contain a nucleus of 

 organic or other nature, upon which 

 the salts are deposited from their solu- 

 tions very much as sugar crystallizes 

 upon threads suspended in a syrup. 



12. Degeneration of Nerves. If a 

 nerve-fibre be severed from its connec- 

 tion with the ganglion-cell of which it 

 is a process, it suffers disintegration. 

 The medullary sheath breaks up into 

 a number of globular masses, which 

 are subdivided and eventually ab- 

 sorbed. The axis-cylinder becomes 

 swollen, granular, and also disappears. 

 If the ganglion-cell retains its vitality. 



FIG. 254. 



Fig. 254. Calcareous infiltration of renal glomeruli, secondary to hyaline degeneration of 

 the capillary walls, obliteration of the vascular lumen, and death of the tissue. The 

 glomerulus to the left shows a slight granular deposit of calcareous material in the 

 hyaline glomerulus. The figure to the right shows the organic base almost completely 

 obscured by calcareous granules. (Ribbert.) 



Fig. 255. Calcareous infiltration of the cardiac muscle. (Langerhans.) a, degenerated car- 

 diac muscle ; b, muscular fibres impregnated with lime-salts. The specimen was taken 

 from a case of chronic lead-poisoning. The cells which are the seat of the calcareous 

 infiltration must have been dead for a considerable time before the death of the indi- 

 vidual. 



it may regenerate the nerve by the development of a new process. 

 If, however, the ganglion-cell has been destroyed, regeneration does 

 not take place. This exemplifies the statement, made in the chapter 

 on the cell, that portions of cells which were devoid of a nucleus 

 could not continue their existence. 



