454 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



is deposited in layers alternating with the white layers of cholesterol. The pig- 

 ment here, as in all other gall-stones, consists always of the calcium salts of the 

 pigments — not of pure bilirubin and biliverdin themselves. Considerable cal- 

 cium carbonate is also usually present, particularly in the green layers of biliverdin- 

 calcium. 



3. Common Gall-bladder Stones. — The composition of this form is but little 

 different from the above, the chief difference being in the structure. They pre- 

 sent externally a firmer crust, usually distinctly laminated; in the center is a softer 

 pigmented nucleus which frequently shows a central cavity containing fluid. 

 Such calculi are not distinctly crystalline in structure, and are small, seldom 

 larger than a cherry. 



4. Mixed Bilirubin-calcium Calculi. — These generally occur singly, but some- 

 times in groups of three or four, and are of large size. Although the chief con- 

 stituent is bilirubin-calcium, there is always much cholesterol, often over 25 per 

 cent. Copper and traces of iron may also be present. Their structure is lamin- 

 ated, with sometimes a crystalline cholesterol nucleus. 



5. "Pure" Bilirubin-calcium Calculi. — In addition to the chief constituent, 

 bihver din-calcium, hilifuscin and hilihumin^^ are practically always present. Bili- 

 humin is at times the chief ingredient, and may form over half of the substance; 

 hilicyanin is rarely present. There is always some cholesterol, but sometimes 

 only traces. These calculi are small, from the size of a grain of sand to that of a 

 pea, and they occur in two distinct forms. One form is of wax-like consistence; 

 the other is harder, steel-gray or black in color, with a metallic luster. Pure bili- 

 rubin and biliverdin, not combined with calcium, are practically never present 

 in concretions. 



6. Rarer Forms. — (a) Amorphous and incompletely crystalline cholesterol gravel. 

 Cholesterol externally giving a pearly luster; pigment in the center. 



(b) Calcareous Stones. — Consist chiefly of a mixture of calcium carbonate and 

 bilirubin-calcium. Calcium carbonate may occur either as a superficial crust, 

 or as small masses within an ordinary calculus; calcium sulphate and phosphate 

 occur rarely in traces. Stones consisting mainly of calcium carbonate are ex- 

 tremely rare in man, but more frequent in cattle and other herbivora, in which 

 all forms of concretions contain much calcium, either combined with pigment 

 or as carbonate and phosphate. A calcium oxalate gall-stone has also been 

 described. ^^ 



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



(d) Casts of Bile-ducts. — Occur particularly in cattle, and consist chiefi}^ of 

 bilirubin-calcium. Rarely and imperfectly formed in man. 



Aschoff and Bacmeister differ somewhat from Naunyn as to the 

 composition of gall-stones, which they classify as follows: 



1. Pure cholesterol stones. 



2. Stratified cholesterol-calcium stones. 



3. Cholesterol-pigment-calcium stones. 



4. Composite stones, composed of cholesterol and a mantle of cho- 

 lesterol and calcium. 



5. Bilirubin-calcium stones, usually found in the bile passages of the 

 liver. 



6. The very rare calcium carbonate stones. 



Formation of QaII=stones. — Until quite recently our views con- 

 cerning the chemistry and pathology of the formation of gall-stones 



*" Biliverdin differs from bilirubin in containing one more atom of oxygen in 

 the molecule, and it is easily formed from bilirubin — even exposure to air will 

 slowly bring about the oxidation. Bilifusciit is a still more oxidized derivative — 

 so much so that it does not give Cmeliii's reaction (with HNO3+HNO2) for bile- 

 l)igments. Bilihumin rei)resents the most oxidized of these products, is brown 

 in color, and is the chief constituent of the residue left after treating gall-stones 

 with ether, alcohol, and chloroform to dissolve out the cholesterol. 



** Montlaur, Bull. sci. i)harmacol., Vol. IS, p. 19. 



