446 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



On the other hand, Wells, ^^ studying large quantities of material 

 chemically, found at most doubtful traces of calcium soaps in calci- 

 fying matter, even in the earliest stages, and also very small amounts 

 of other soaps or fatty acids, and, therefore, questions the occurrence 

 of calcium soaps as an essential step in calcification, although not 

 doubting that under certain conditions {e. g., calcifying lipomas, fat 

 necrosis) this may occur. In calcification at all stages the propor- 

 tion of calcium carbonate and phosphate was found quite constant, 

 and exactly the same as in normal bone; namely, in the proportion 

 expressed by the formula 3(Ca3(P04)2:CaC03, which Hoppe-Seyler 

 advanced to express the composition of the salts of bone. Hence it 

 seems probable that there are no essential differences between the 

 processes of ossification and pathological calcification,^" and there 

 seems to be as yet no reason for assuming that in the former calcium 

 soaps constitute an essential step in the process. 



Phosphoric Acid in Calcification. — It has generally been as- 

 sumed that in normal ossification the calcium is combined by phos- 

 phoric acid, which probably is derived from the cartilage cells, possibly 

 through autolysis of the nucleoproteins or some similar process. ^^ 

 Grandis and Mainini,^^ by using microchemical methods, thought 

 that they found evidence that the phosphorus of ossifying cartilage is 

 converted from an organic combination into an inorganic form (P2O5), 

 which then takes up calcium from the blood. The methods used have 

 been questioned, and Pacchioni,^^ from his studies, was inclined to the 

 opinion that the calcium entered the cartilage already combined as 

 phosphate. Wells implanted into the abdominal cavity of rabbits 

 various tissues that had been killed and sterilized by boiling, and 

 found that tissues rich in nucleoproteins showed no tendency to take 

 up calcium in greater amounts than did tissues poor in nucleoproteins, 

 which result speaks against the idea that phosphoric acid derived 

 from nucleic acid combines the calcium. On the other hand, im- 

 planted dead cartilage soon became thoroughly impregnated with 

 calcium salts, which seemed to be deposited in the same proportion 

 as to carbonate and phosphate as in bone. 



Physical Absorption of Calcium Salts. — As there could be no 

 question of "vital activity" on the part of this boiled cartilage, it 

 seems most probable that there exists in cartilage a specific absorp- 

 tion affinity for calcium salts, similar to the absorption affinity that 

 Hofmeister^^ observed exhibited by other organic colloids (gelatin 



29 See review in Arch. Int. Med., 1911 (7), 721. 



^^ Dyes that stain the bones when fed to living animals (madder) also stain 

 pathological calcific deposits (Macklin, Anat. Kecord, 1917 (ll), 387). 



^' Hanes, who observed that the i)hosi)hatids disaj)pcar from the liver of the 

 developing chick, suggests this as a source of the phosphoric acid required for 

 ossification (.Jour. Exper. Med., 1912 (16), 512). 



^2 Arch, per la sci. Med. Torino, 1900 (24), 67. 



" Jahrb. f. Kinderheilk., 1902 (56), 327. 



" Arch, exper. Path. u. Pharm.. 1891 (28), 210. 



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