368 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



of Virchow. 1 In conditions with much destruction of bone, 

 as osteomalacia, caries, osteosarcoma, etc., deposits of lime 

 salts have been found distributed diffusely in various organs, 

 particularly in the lungs and stomach. As there is no evidence 

 that these organs had been the site of any diffuse tissue necro- 

 biosis before the calcification occurred, it seems probable that the 

 deposits have been made in practically or quite normal organs, 

 because of oversaturation of the tissue fluids by calcium salts. 

 The fact that the lung and stomach, and also to a less degree 

 the kidney, are picked out, suggests that the calcification is 

 related to the fact that in these same organs we have the 

 excretion of acids into their cavities, which leaves the fluids in 

 the substance of the organs correspondingly alkaline, and an 

 increase in the alkalinity of the fluids makes the calcium salts 

 decidedly less soluble. Presumably, under normal conditions, 

 the amount of calcium in the blood is too slight to be thrown 

 down in this way, but when oversaturated because of the calcium 

 absorption in the skeleton, precipitation occurs in the parts of 

 the body where the alkalinity of the blood or tissue fluids is 

 greatest. A number of cases similar to the metastatic form as 

 to location and nature of the deposits have been observed un- 

 accompanied by any bone absorption, which complicates the 

 matter decidedly, and some writers 2 combat many of the pre- 

 vailing ideas of metastatic calcification. Some have attempted 

 to include the calcification of the vessels and other tissues in 

 old age in the metastatic calcifications, ascribing the origin of 

 the salts to the senile absorption of bone, but it is probably 

 dependent rather upon the extensive hyaline degeneration of 

 the connective tissues that occurs in the senile scleroses. 



CHEMISTRY OF THE PROCESS OF CALCIFICATION 



In analyzing the etiological factors in the production of path- 

 ological calcification for the purpose of determining the chem- 

 ical changes that occur in the process, we have the following 

 facts upon which to base the consideration : 



(1) The calcium salts must come from the blood, where they 

 are held in solution or in suspension by the proteids, either as the 

 carbonate and phosphate themselves, or as calcium-ion-proteid 

 compounds, or perhaps both. This suspension or solution is an 

 unstable condition, possible only because of the extremely small 

 proportion of calcium in the blood (about 1 : 10,000), and, there- 



1 Virchow's Arch., 1855 (8), 103; review by Kockel, Deut. Arch. klin. 

 Med., 1899 (64), 332. 



2 Beer, Jour. Path, and Bact., 1903 (9), 225. 



