Cholelithiasis. — Biliary Calculi. — Gall Stones. 517 



pressure and wear they assume various polygonal forms. If they 

 lie apart in the gall ducts or bladder they are regularly rounded. 

 They are sometimes mulberry shaped as if conglomerate. In 

 other cases the solid masses are so small as to have secured them 

 the name of biliary sand. Casts and incrustations in the ducts 

 are not necessarily made up of smaller globular masses. 



On section a calculus shows a nucleus, composed of bile pig- 

 ment, blood, mucus, with the debris of parasites or bacteria. 

 Around this nucleus the calculus is deposited in concentric layers, 

 of a hard material consisting largely of cholesterine, but contain- 

 ing also bile coloring matter, bile salts, and lime, in short all the 

 constituents of bile. 



Causes. Various conditions contribute to the precipitation of 

 biliary solids in the form of calculi or encrustations. The most 

 prominent causes are : lack of exerci.se, over-feeding, dry feed- 

 ing, concentration of the bile, the presence of colloids and bac- 

 terian infection. 



Idleness is especially operative in cattle, which are quite subject 

 to biliary calculi and concretions, when shut up in the stall on 

 abundant, dry feeding for a long winter. They are not noticed 

 in stalled animals, that are fed watery or succulent rations, such 

 as green fodder, distiller's or brewer's swill, ensilage, brewer's 

 grains, mashes, roots, potatoes, apples, pumpkins, and in case a 

 tendency to their formation is developed on the dry feeding of 

 winter, the concretions may be re-dissolved and entirely removed 

 by the succulent spring grass. A similar influence is noticed in 

 the human family, as the female sex living mostly indoors, and 

 males pursuing sedentary occupations furnish the greatest number 

 of gall stones. 



Concentration of bile results in part from muscular inactivity 

 and hepatic torpor, but also from over-feeding which loads the 

 portal blood and indirectly the bile with an excess of solids, and 

 from dry feeding which lessening the secretion of water leaves 

 the, bile more dense and predisposed to precipitate its solids. The 

 density of the liquid, however, developed from a rich and dry 

 ration and a prolonged inactivity, may continue for a length of 

 time, without the occurrence of actual precipitation. It usually 

 requires some additional factor to make this predisposition a 

 direct cause. 



