388 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



Usually, however, pancreas stones consist chiefly of inorganic 

 substances. Johnson and Wollaston report analyses of two 

 stones, one containing 72.30 per cent, calcium phosphate and 

 but 8.80 per cent, organic matter; the other 91.65 per cent, 

 calcium carbonate, 4.15 per cent, magnesium carbonate, and 

 but 3 per cent, organic matter. Legrand 1 found only 0.7 per 

 cent, organic matter in another concretion which contained 93.1 

 per cent, calcium carbonate. Pancreatic juice, being strongly 

 alkaline, can hold but a small quantity of calcium salts in solu- 

 tion (normally but 0.22 part per thousand C. Schmidt); pre- 

 sumably the little normally present is held in the form of a 

 colloidal suspension by the proteids. Possibly when stasis 

 occurs, digestion of the proteids leads to the precipitation of 

 the calcium salts, or, more probably, the excessive calcium is 

 largely derived from the exudate from the inflamed ducts, as 

 seems to be the case with the calcium of biliary calculi. 



Salivary Calculi. 2 These have a similar composition, in 

 the main, to the concretions of the pancreatic duct, except that 

 they generally contain more organic matter, resembling in this 

 respect the " tartar" of the teeth. Bessanez found in one 81.3 

 per cent, of calcium carbonate and 4.1 per cent, of calcium phos- 

 phate, whereas in another the carbonate was but 2 per cent, and 

 the phosphate 75 per cent. Potties has described a calculus 

 with a central portion composed chiefly of uric acid and a periph- 

 eral portion containing 69 per cent, of calcium phosphate and 

 20.1 per cent, of calcium carbonate. Harlay 3 found in one 

 specimen 15.9 per cent, organic matter, 75.3 per cent, calcium 

 phosphate, 6.1 per cent, calcium carbonate. Eoberg believes 

 that bacteria alone do not usually cause salivary calculi to 

 form, but that a foreign body entering the duct is the chief 

 factor. Increased alkalinity may also favor precipitation of 

 calcium from the saliva. In Koberg's case of sialolithiasis the 

 saliva was of normal composition. 



Intestinal Concretions. These always have a nucleus 

 of some indigestible foreign substance, most often hair, but 

 sometimes cellulose structures or solid indigestible particles, 

 including gall-stones, fruit-stones, bone, etc. The bulk of the 

 concretions is usually made up chiefly of ammonio-magnesium 

 phosphate, with some calcium phosphate, carbonate, and sul- 

 phate, proteid matter, and occasionally calcium and magnesium 



1 Jour. Pharm. et Chim., 1901 (14), 21. 



2 Literature, see Roberg, Annals of Surgery, 1904 (39), 669. 



3 Jour. Pharm. et Chim., 1903 (18), 11. 



