BILIARY CALCULI 379 



starting-point ; this injury is usually produced by infection, the 

 colon and typhoid bacilli being the most common organisms in 

 this process. 1 It is probable that injury alone is not sufficient 

 to cause gall-stone formation, but infection is essential (Miyaka 2 ). 

 Through the degeneration of the epithelial cells an excess of 

 cholesterin is formed, while at the same time the desquamated 

 cells and clumped bacteria offer suitable nuclei upon which the 

 cholesterin begins to crystallize out. Apparently after the cal- 

 culi have reached a certain size they cause sufficient mechanical 

 injury to keep up the cell degeneration and cholesterin forma- 

 tion, even after the infection has subsided. A certain amount 

 of infection and inflammation is a favoring condition, however, 

 for Harley and Barratt 3 found that fragments of cholesterin 

 calculi introduced aseptically into the gall-bladders of dogs 

 were slowly dissolved and disappeared, but this was prevented 

 by infecting the gall-bladder with I>. coli. According to 

 Naunyn's investigations, it is not an alteration in the composi- 

 tion of the bile, as formed in the liver, which causes the precipi- 

 tation of cholesterin, but rather the presence of the nidus, and 

 the production of large quantities of cholesterin in immediate 

 proximity to this nidus, that determines the formation of a con- 

 cretion. In case the bile stagnates in the gall-bladder, the 

 cholesterin that is being constantly formed by the normal dis- 

 integration of surface epithelium accumulates, until, even without 

 infection, there forms a sediment of soft yellowish and brown- 

 ish masses, consisting chiefly of cholesterin and bilirubin-calcium. 

 From this material calculi may eventually form, and by their 

 irritation lead to further formation of cholesterin and increased 

 growth. But bacteriological studies indicate that generally an 

 infectious influence is present in cholelithiasis, and bacilli may 

 be found alive in gall-stones for remarkably long periods. 



It was formerly supposed that the calcium-pigment concre- 

 tions were produced by the presence of excessive calcium in the 

 bile, derived particularly from lime-laden drinking-water, but 

 it has been demonstrated that increase of calcium in the food 

 does not cause an increase in the amount in the bile. Further- 

 more, on concentrating bile, which contains both bilirubin and 

 calcium, the free bilirubin separates out and not the calcium 



^ee Cashing (Johns Hopkins Hosp. Bull., 1899 (10), 166), who produced 

 gall-stones experimentally by injecting typhoid bacilli into the circulation after 

 injuring the gall-bladder. Literature on the relation of bacteria to gall-stones 

 given by Cushing ; also by Pratt, Amer. Jour. Med. Sci., 1901 (122), 584; by 

 Bierring, Jour. Amer. Med. Assoc., 1904 (43), 1099; and by Herter (loc. etV.). 



2 Mitt. a. d. Grenzgeb. Med. u. Chir., 1900 (6), 479. 



3 Jour, of Physiol., 1903 (29), 341. 



