CHAPTER XV 



CALCIFICATION, CONCRETIONS, AND 

 INCRUSTATIONS 



CALCIFICATION l 



Pathological calcification occurs in two forms : one is a pre- 

 cipitation of calcium in secretions and excretions of the body ; 

 the other is the deposition of calcium salts in the tissues them- 

 selves. The former, which includes not only concretions in 

 general, but probably also the deposition of calcium salts in the 

 cells and tubules of the kidney, 2 both in disease and in experi- 

 mental calcification after certain poisonings, is readily enough 

 explained in most instances by recognizable alterations in the 

 composition of the secretions, which lead to simple chemical 

 precipitations. With this form we shall deal in the subsequent 

 consideration of concretions, but, in referring to calcification, 

 shall indicate only depositions within the tissues. 



Relation of Calcification to Ossification. In normal 

 ossification we have to deal with the accumulation of lime salts 

 within the stroma or cells of a tissue that has usually undergone 

 certain preparatory changes in the way of formation of a more 

 or less homogeneous ground substance, but has not suffered a 

 total loss of vitality, although vitality is possibly decreased. 

 Pathological calcification is similar, in so far as we have to deal 

 with deposition of much the same salts in tissues that have 

 suffered either total or partial loss of vitality, and which very 

 frequently indeed are hyaline. What appear to be essential 

 differences are these : (1) In calcification the lime salts always 

 remain in clumps and masses, often fusing to greater or less 

 degree, but never with the diffuse even permeation of tissue seen 

 in ossification. (2) All the cells within a calcified area, if not 

 dead at the beginning of the process, eventually disappear for 

 the most part, and we have sooner or later a perfectly inert 

 mass, practically a foreign body, instead of a specialized tissue 

 as in ossification. (3) Ossification is accomplished only in 



1 Literature and re'sum^ : Pfaundler, Jahrb. f. Kinderheilk., 1904 (60), 

 123 ; Wells, Jour. Med. Research, 1906((14), 491. 



2 See v. Kossa, Ziegler's Beitr., 1901 (29), 163. 



364 



