466 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



since simple experimental stasis will not cause their formation.'" The calculi 

 consist usually of a mixture of calcium phosphate and carbonate, associated with 

 more or less organic matter, including frequently cholesterol, but all the usual 

 products of proteolysis may be present because of the presence of trypsin. Oc- 

 casionally the calculi consist chiefly of calcium carbonate, which may be almost 

 pure.'^ Shattock^2 ^^g observed a pancreatic concretion composed of calcium 

 oxalate. Sodium phosphate and chloride, magnesium phosphate, and proteins 

 have also been found in these concretions. Taylor^' describes a pancreatic con- 

 cretion containing, according to the analyst, chiefly silicate (!), a finding difficult to 

 understand or accept. 



Baldoni'^ found, on analysis of a stone weighing 3.1 grams, the following 

 percentage composition: 



Water 3 . 44 



Ash 12.67 



Proteins 3 . 49 



Free fatty acids 13 . 39 



Neutral fatty acids 12 . 40 



Cholesterol 7 . 69 



Pigments and soap 40 . 91 



Undetermined 6.01 



Usually, however, pancreas stones consist chiefly of inorganic substances. 

 Johnson and WoUaston 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'^ 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 solution 

 (normally but 0.22 part per thousand — C. Schmidt); presumably the little nor- 

 mally present is held in the form of a colloidal suspension by the proteins. Possi- 

 bly when stasis occurs, digestion of the proteins 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 biUary 

 calculi. 



Salivary Calculi.'^ — These have a similar composition, in the main, to the con- 

 cretions 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 phosphate, 

 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 peripheral portion containing 69 per cent, of calcium phosphate 

 and 20.1 per cent, of calcium carbonate. Harlay^* found in one specimen 15.9 

 per cent, organic matter, 75.3 per cent, calcium phosphate, 6.1 per cent, calcium 

 carbonate. Roberg believes that bacteria alone do not usually cause salivary 

 calculi to form, but that a foreign body entering the duct is the chief factor. In- 

 creased alkalinity may also favor precipitation of calcium from the saliva. In 

 Roberg'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 sulphate, protein matter, and occasionally 



'« See Lazarus, Zeit. klin. Med., 1904 (51), 530. Literature. 

 " Rosenthal, Arch. f. Verdauungskr., 1914 (20), 619. 

 " Brit. Med. Jour., 1896 (i), 1034. 

 " Lancet, Dec. 18, 1909. 

 " Schmidt's Jahrb., 1900 (268), 210. 

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

 '"Literature, see Roberg, Annals of Surgery, 1904'(39), t)69. 

 " Particles of gold have been found in a salivary calculus by Maurin (Repert 

 pharm., 1919 (30), 257), presumably derived from fillings. 

 '8 Jour. Pharm. et Chim., 1903 (18), 11. 



