380 BILIARY CALCULI. [BOOK II. 



cases, the bases of the crystalline pyramids project to the very 

 external surface as mammillated protuberances. When an external 

 layer exists, it is almost always very clearly distinguished from the 

 middle zone, by its colour, its stratified appearance, and its con- 

 sistence. It is sometimes composed of cholesterin arranged in thin 

 layers, which, when seen in section, appear to be separated by striae 

 of biliary pigment. In other cases, the external layer is due to the 

 compound of biliary pigment and calcium forming one or several 

 layers of greater or less thickness and possessed of a brown or green 

 colour. Finally, the external layer may present strata of calcium 

 carbonate separated by pigmentary deposits 1 ." 



Naunyn's Naunyn, in his monograph on cholelithiasis, adopts 



classification the following classification of biliary calculi: (1) pure 

 cholesterin calculi : (2) stratified cholesterin calculi : 

 (3) the common biliary calculi, that is the usually 

 yellow or whitish-brown calculi which are found in considerable 

 numbers in the gall-bladder, which . commonly are facetted and 

 are often of a soft or friable consistence, when first obtained : (4) the 

 mixed bilirubin-calcium calculi, which occur singly or to the number 

 of two or three in the gall-bladder or the large biliary passages and 

 which when multiple may present facets. They are either composed 

 entirely of a reddish-brown or dark-brown mass, or they possess a 

 central, laminated, cholesterin nucleus. Even those parts of the stone 

 which appear to consist almost entirely of bilirubin contain as much 

 as 25 per cent, of cholesterin : (5) pure bilirubin-calcium stones. 

 These are never large, varying from the size of grains of sand to that 

 of peas. For the most part, they have the consistence of wax, though 

 a variety occurs which is harder ; the latter, which are usually very 

 minute and never larger than peas, are of a steel-grey or blackish 

 colour and possess a metallic lustre. 



The small calculi are composed in great part of bilirubin-calcium, 

 though they always contain biliverdin-calcium, besides bilifuscin and 

 bilihumin ; they very rarely contain bilicyanin. The calculi belonging 

 to this class contain very small quantities of cholesterin ; sometimes 

 barely recognisable traces. 



(6) Rarer forms of biliary calculi, which include some already 

 referred to in Charcot's description, viz. (a) amorphous and imper- 

 fectly crystallised cholesterin stones of small size: (b) calculi con- 

 taining calcium carbonate. This salt is often present in large 

 quantities in addition to bilirubin-calcium. Naunyn has often found 

 the nucleus of the common gall-stones to be composed of agglomera- 

 tions of spheres and warty masses of calcium carbonate: (c) con- 

 cretions with heterogeneous bodies as a nucleus, or concretions which 

 may be termed conglomerate stones : (d) casts of the hepatic ducts 2 . 



1 Charcot, op. cit. p. 122 et seq. 



2 B. Naunyn, Klinik der Cholelithiasis (Mit 3 farbigen und 2 lichtdruck Tafeln). 

 Leipzig, Verlag von F. C. W. Vogel, 1892. Kefer to p. 1 6. The Author wishes to 



