378 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



herbivora, in which all forms of concretions contain much 

 calcium, either combined with pigment or as carbonate and 

 phosphate. 



(c) Concretions with included bodies, and conglomerate stones. 



(d) Casts of Bile-ducts. Occur particularly in cattle, and 

 consist chiefly of bilirubin-calcium. Rarely and imperfectly 

 formed in man. 



Formation of Gall-stones. We owe our present 

 understanding of the chemistry and pathology of the formation 

 of gall-stones chiefly to Naunyn l and his pupils. Former 

 observers, having learned that bile normally contains cholesterin 

 (Hammarsten found from 0.06-0. 16 per cent, in human bile), 

 sought the cause of gall-stones in either an increased elimina- 

 tion of cholesterin by the liver, or a decrease in the power of 

 the bile to hold the cholesterin in solution. Thus Frerichs, 

 finding that the presence of large amounts of bile salts and an 

 alkaline reaction favored the solution of cholesterin, imagined 

 that a diminution of either bile salts or alkalinity led to the 

 precipitation of the cholesterin. Naunyn and his pupils, how- 

 ever, demonstrated that the amount of cholesterin present in 

 the bile does not depend upon the amount taken in the food or 

 the amount present in the blood ; and that it did not vary in 

 disease, except when gall-stones were present. They concluded 

 that the cholesterin of the bile is neither a product of general 

 metabolism nor a specific secretion-product of the liver. Find- 

 ing that pus and the secretions from inflamed mucous membranes 

 (bronchitis) contained as much cholesterin as did normal bile, 

 and often more, they concluded that the chief source of choles- 

 terin in gall-stone formation was from the degenerating and 

 desquamated epithelial cells of the gall-bladder and bile tracts. 

 This idea was supported by the large amount of cholesterin 

 found in the contents of gall-bladders shut off from the com- 

 mon duct, and by the formation of gall-stones in such isolated 

 gall-bladders. Further evidence has since been brought for- 

 ward in favor of this same view, 2 until it is now generally 

 accepted as correct. It is now believed that the ordinary steps 

 in the formation of a cholesterin concretion are as follows : 

 Some injury to the mucous membrane of the bile tracts is the 



1 An English translation of this classic work, by A. E. Garrod, has been 

 published by the Sydenham Society, 1896, vol. 158. 



2 Thus Wakeman (quoted by Herter, Trans. Congress Amer. Physicians, 

 1903 (6), 158; excellent resume) was able to cause an increase in the choles- 

 terin of the bile in the gall-bladder of dogs by injecting into it HgCl 2 , phenol, 

 or ricin. At first the cholesterin seems to be contained largely in the degenerat- 

 ing desquamated cells. 



