OSTEn}rALAnA 447 



disks) toward various crystalline suhstaiiccs in solution. It is of sig- 

 nificance that the substances in which calcium is deposited are, in 

 most instances, of similar physical character, being homogeneous and 

 often hyaline, although of the most varied chemical composition; in 

 other words, they agree much more in physical than in chemical struc- 

 ture. Also we find that hyaline tissues with an affinity for calcium 

 often exhibit a similar affinity for other substances, such as pigment and 

 iron.^^ Hofmeister advances the hypothesis that when the cartilage 

 or other matrix becomes saturated with calcium salts, any decrease 

 in COo content of the solution will lead to a precipitation of calcium 

 salts, thus restoring to the cartilage its power of absorbing more 

 calcium salts whenever the fluid comes to it with a higher degree of 

 saturation with calcium salts and CO2. This hypothesis is in har- 

 mony with Barille's observation that when the C02 is reduced the 

 complex carbon-phosphate of calcium precipitates a mixture of car- 

 bonate and phosphate in the same proportions as found in bones and 

 calcific deposits generally. The fact that this ratio (10 to 15 per 

 cent. CaCOs and 85 to 90 per cent. Ca?(P03)4), is found in all stages 

 of calcification, is entirely in favor of the above hypothesis, and 

 opposed to the idea that any special chemical precipitant formed in 

 the calcifying area is responsible for the deposition of calcium. Taken 

 all in all, the evidence seems in favor of the view that normal ossifica- 

 tion and pathological calcification (except metastatic calcification 

 and the calcification of fat necrosis and other areas of necrotic fat 

 tissue) depend more upon physico-chemical factors and variations in 

 CO2 concentration than upon the presence of chemical precipitants 

 in the tissues. This view is supported by the observation of IMacklin^'' 

 that calcifying and ossifying tissues become stained alike with madder 

 fed during their formation, through the deposition of stained calcium 

 salts from the blood. 



Osteomalacia" 



In this condition the quantity of inorganic salts in the bone is 

 greatly decreased, while, at the same time, their place is taken in part 

 by new-formed osteoid tissue; as a result, the proportion of the weight 

 of the bone formed by inorganic salts is reduced to as lew as 20 to 

 40 per cent., instead of being from 56 to 60 per cent., as in normal 

 bone. This has suggested that the cause of the disease may be a 

 solution of the lime salts by some acid, but Levy^^ found that in osteo- 

 malacia the proportion of calcium carbonate and phosphate in the 



" See Sprunt, Jour. Exp. Med., 1911 (14), 59. 



'« Jour. Med. Res., 1917 (36), 493. 



" See also review in Albu and Neuberg's "Mineralstoffwechsel," Berlin. 1906, 

 pp. 124^127; bibliography by Zesas, Cent. Grenz. Med. u. Chir., 1907 (10), 801; 

 full discussion by McCrudden, Arch. Int. Med., 1910 (5), 596; 1912 (9), 273. 



38 Zeit. physiol. Chem., 1894 (19), 239. 



