CHAPTER XV 



CALCIFICATION, CONCRETIONS, AND 

 INCRUSTATIONS 



CALCIFICATION ' 



Pathological calcitication occurs in two forms: one is a precipita- 

 tion of calcium in secretions and excretions of the body; the other 

 is the deposition of calcium salts in the tissues themselves. 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,- both in disease and in experimental calcification after cer- 

 tain poisonings, is readily enough explained in most instances by rec- 

 ognizable alterations in the composition of the secretions, which lead 

 to simple chemical precipitations. With this form w^e shall deal in 

 the subsequent consideration of concretions, but, in referring to calci- 

 fication, shall indicate only depositions from the blood directly into the 

 tissues. 



Relation of Calcification to Ossification. — In nonnal 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, al- 

 though vitality is possibly decreased. Pathological calcification is 

 similar, in so far as we have to deal Math deposition of quite the same 

 salts in tissues that have suffered either total or partial loss of vital- 

 ity, and which ver\^ frequently indeed are hyaline. Wliat 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 perfect!}- inert mass, practically 

 a foreign body, instead of a specialized tissue as in ossification. (3) 

 Ossification is accomplished only in varieties of connective tissue, 

 but calcification may involve any sort of cell or tissue provided it 

 is degenerated sufficiently. Furthermore, any area of calcification 



1 Literature and r#siim#: Pfaundlcr, Jahrb. f. Kinderheilk.. 1904 (00), 123; 

 Wells, Jour. [Nfed. Research, 1006 (14), 491, and Arch. Int. Med.. 1011 (7), 721; 

 Hofmeister. Ergebnisse Physiol., 1910 (9), 429; Schultze, Ergebnisse Pathol., 

 1910, XIV (2), 706. 



2 See Wells, Holmes and Henry, Jour. Med. Research, 1911 (25), 373. 



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