BILIARY CALCULI 453 



between the colloidal particles. On the other hand, the concentra- 

 tion of the crystalloids on the surface of the colhjidal particles causes 

 the colloids to serve as the starting point of precii)itation whenever 

 the crystalloids are in excess. When the crystalloid goes out of solu- 

 tion, therefore, it will form crystals or precipitates which are most 

 intimately associated with the colloids, as we see when uric acid 

 crystallizes out of urine, taking with it the colloidal pigments by which 

 it is absorbed. Or, if the colloids are precipitated, the solvent power 

 of the solution is reduced, and the crystalloids will deposit in intimate 

 relation to the colloids. As Schade pointed out, if a colloid precipi- 

 tates in an irreversible form {e. g., fibrin), the concretion will be per- 

 manent, as with ordinary concretions, but if the colloid precipitate is 

 reversible the mass may be dissolved again, as with the precipitate of 

 urates in the tubules of the infant's kidney. 



Biliary Calculi'^ 



As may be judged from the above statements, concretions are never 

 composed of one substance in a pure form, but usually consist of a 

 mixture of the constituents of the fluid in which they are developed. 

 This is particularly true of gall-stones, which contain in greater or 

 less quantities several or all of the constituents of the bile. While 

 cholesterol forms the greater part of nearly all biliary concretions, and 

 is present in greater or less amounts in all, calcium salis of the bile- 

 pigments are always present; usually inorganic salts of calcium (car- 

 bonate and phosphate) are also present, as well as small amounts of 

 fats, soaps, lecithin, mucus, and other products," and occasionally 

 traces of copper, '^^ iron, and manganese. '^^ The quantity of bile 

 salts, the chief constituent of the bile, is usually extremely minute, 

 apparently only so much as may percolate into the crevices of the con- 

 cretion. However many stones there may be in a gall-bladder, they 

 usually are all of approximately the same composition and structure. 



In gall-stones from the domestic animals the proportion of inor- 

 ganic salts is usually much higher than it is in man. 



Naunyn has classified gall-stones according to their composition, 

 as follows: 



1. "Pure" Cholesterol Stones. — The purity is only relative, since even the 

 purest alwaj'S contain some pigment as well as a stroma and a nucleus; but the 

 amount of cholesterol may reach 98 per cent., and is usually over 90 per cent. 

 Crystalline structure is usually well marked, while stratification is slight. The 

 color varies from nearl}^ pure white to yellow, or even brown on the surface. 



2. Laminated Cholesterol Stones. — These consist of about 75-90 per cent, of 

 cholesterol, and differ from the preceding form in containing more pigment, which 



"8 Bibliography by Bacmeister, Ergeb. inn. Med., 1913 (11), 1. 



^^ Fischer and Rose found about 0.1 gm. carotin in 1280 grns. gall stones from 

 cattle. (Zeit. physiol. Chem., 1913 (88), 331.) 



'8 See Mizokuchi, Cent. f. Pathol., 1912 (23), 337. 



"^Gall-stones have been found enclosing droplets of mercury. (Xaunyn, 

 Frerichs.) 



