372 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



while other observers have stated that in osteomalacia the 

 alkalinity of the blood is reduced, and that lactic acid appears 

 in the urine. All the above statements are of questionable 

 value, and it is improbable that there is any such degree of 

 acidity or, better, lack of alkalinity, in the blood or fluids in the 

 bones as to dissolve out the inorganic salts. Levy l found that 

 in osteomalacia the proportion of calcium carbonate and phos- 

 phate in the bones remains constant, as also does the proportion 

 of calcium and phosphoric acid ; if the decalcification occurred 

 through solution by lactic or other acids, the carbonate should 

 be decomposed first, whereas the lime salts seem to be taken 

 out as molecules of calcium carbonate-phosphate ; i. e., in the 

 same proportion as they exist in the bone. On the other hand, 

 it has been found in Pawlow's laboratory that dogs kept for 

 long periods after a pancreatic fistula has been established, 

 develop a condition resembling osteomalacia, 2 which would 

 seem most reasonably explained as due to the constant loss 

 of alkali in the pancreatic juice. Histologically, absorption 

 seems to depend largely upon a direct eating out of bone 

 tissue, both organic and inorganic substance, by osteoclasts 

 (Cohuheim), followed by a formation of an uncalcified osteoid 

 tissue. (Senile osteoporosis differs chiefly in that no new osteoid 

 tissue is formed.) According to Schmidt and to Langendorif 

 and Mommsen, this new-formed osteoid tissue yields no gelatin, 

 and, therefore, is quite different from normal osteoid tissue. It 

 is not established, however, that this alteration is a constant 

 occurrence in osteomalacia. In many cases of osteomalacia the 

 rapid rate of progress of the disease indicates that it is not 

 simply a normal absorption of lime salts with defective replace- 

 ment, but that an excessive absorption must occur (Pommer 3 ). 

 Chabrie 4 found that much of the calcium absorbed is replaced 

 by magnesium, so that the latter may be in excess of the former ; 

 he found in one case 22.2 per cent, of CaO and 26.9 per cent, 

 of MgO. Malcolm 5 has found that ingestion of considerable 

 quantities of magnesium salts causes loss of calcium in adult 

 animals, and hinders its deposition in growing animals, but 

 there is no evidence to connect this fact with the increased 

 magnesium in the bones in osteomalacia. 



Studies of metabolism in osteomalacia have shown a loss of 



1 Zeit. physiol. Chera., 1894 (19), 239. 



2 Personal communication from Dr. Boris Babkin. 



3 Vierordt, Nothnagel's System, vol. 7, part ii, p. 124. 



4 Les phenomenes chim. de 1' ossification, Paris, 1895. 



5 Jour, of Physiol., 1905 (32), 182. 



