440 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



Composition of the Deposits in Calcification.^ — The composi- 

 tion of the inorganic salts in calcified areas in the body seems to be 

 practically the same, if not identical, whether the salts are laid down 

 under normal conditions (ossification) or under pathological condi- 

 tions. With the blood continually passing between the bones and 

 the calcified areas, the composition of the two must inevitably become 

 similar or identical. This may be shown by a table giving the pro- 

 portion of inorganic salts found by analysis of normal bone, and the 

 proportion found in calcified materials.^ 



Mg3(P04)2 



CaCOs 



Cai(P04)j 



Pathological Calcification 



Bovine tuberculosis 



Bovine tuberculosis 



Bovine tuberculosis 



Bovine tuberculosis (softened gland) 



Human tuberculosis 



Calcified nodule in thyroid . . . 



Thrombus, human 



Normal Ossification 



Human bone (Zalesky) 



Human bone (Carnot) 



Human bone (Carnot) 



Ox bone (Zalesky) 



Ox bone (Carnot) 



85.9 

 85.4 

 86.4 

 90.6 

 87.8 

 85.4 

 86.5 



83.8 

 87.4 

 87.8 

 86.1 

 85.7 



Iron may be present in pathological calcification, and, according 

 to Gierke,^ in the fetus the entire skeleton contains iron as far as it 

 has calcified, most at the points of active ossification. This statement 

 has been questioned by Hiick and others, who believe that most of 

 the iron demonstrable in normal ossification is the result of an arti- 

 fact, for calcium deposits seem to have a great afiinity for iron. Be- 

 cause of this, pathological calcium deposits take up iron from old 

 hemorrhages in the vicinity, and so in many areas where there have 



^ MacCordick (Lancet, Oct. 18, 1913) has advanced the interesting hypothesis 

 that calcific deposits during life exist mostlj^ as soft masses, like unset mortar. 

 Only when sufficient accumulation of CO2 occurs, as after death, or in the center 

 of large areas of low vitality, such as fibroids, do the deposits become hardened; 

 e.g., in a gangrenous leg the calcified vessels are stiff and brittle, while higher 

 up in the living tissues they are soft and pliable. This would explain why we do 

 not more often observe fractures of calcified arteries. As yet this hypotliesis has 

 not received the critical tests its importance deserves. If true it will explain 

 the cases of extensive calcification of the pericardium in which the heart is so 

 encased that function would seem impossible if the deposit were rigid during 

 life. (Sec Trans. Chicago, Pathol. Society, 1911 (8), 109, for consideration of 

 pericardial calcification.) However, Klotz (Jour. Med. Res., 1916 (34). 495) 

 has questioned the correctness of MacCordick's views on the basis of the occa- 

 sional occurrence of fractures of calcified arteries, but without experimental evi- 

 dence contradicting MacCordick. 



« Wells, loc. cit. 



' Virchow's Arch., 1902 (167), 318. 



