454 CALCJFicAriox, coxcnirr/oxs. \\i> ixchTsTAriows 



rubin, especially billhunilii, it is p()ssil)l(' that oxidatiou processes in 

 the stagnating bile are im])ortant causes of the precipitation; Naunyn 

 suggests that bacteria may be the cause of the oxidation. Pigment 

 calculi are particularly important as the starting-point of the larger 

 mixed calculi. It is possible, Naunyn believes, for the pigment to be 

 later gradually replaced hy cholesterol. 



URINARY CALCULI >■•■> 



These differ from the l)ile concretions in two imi)ortant respects: 

 First, there is no evidence that any considerable part of tlieir con- 

 stituents may come from the walls of the cavities that contain them; 

 they are usually deposited on account of an over-saturation of the 

 urine, or on account of a change in composition of the urine, which 

 renders them insoluble. Second, the composition of urinary calculi is 

 usually less mixed than that of biliary calculi, although seldom, if ever, 

 is it pure. Thus, Finsterer found but six concretions composed of 

 only one substance, in a collection of 114 calculi. As with the bile, the 

 chief constituent of the urine (urea) is so soluble that it never forms 

 concretions, but only the less soluble minor constituents are thrown 

 down. For the formation of calculi, however, it is not sufficient to 

 have merely an excess of a substance in the urine, for we may have 

 deposition of urates, phosphates, or uric acid in simple crystalline 

 form without the formation of calculi. A nucleus of some sort is 

 present as well as a binding substance,''^ which is often mucus derived 

 from the walls of the passages, although the center of the concretion 

 most often consists of uric acid or urates. 



Although the amount of colloidal material in urine is relatively 

 small, yet it undoubtedly plays an important part in maintaining in 

 solution the less soluble crystalloids, which are especially the urates 

 and calcium oxalate. Normal urine contains no colloids which form 

 irreversible gels, and hence ordinary deposits can be readily dissolved, 

 but in inflammatory conditions there appears fibrinogen which readily 

 forms the irreversible fibrin, and conditions thus become favorable 

 for the formation of concretions of any crystalloid with which the 

 urine m'dy be saturated or over-saturated at the time (Schadeh 

 Possibly other colloids may play a similar role. Aschoff' and Kleiu- 

 schmidt "' hold that most urinary calculi begin as primai-y calculi, 

 formed independent of inflammation from excess of the nmin con- 

 stituent (uric acid, oxalates, xanthine, but chiefly ammonium urate) : 

 this calculus foniis the ciystalline nucleus of tlie laminated second- 

 ary deposits of other sul)stances, chiefly uric acid, oxahites and phos- 



•■'!• fipneral liihiiofrrapliy ;iivoii liy Fiiistoror. Dcut. Zcit. kliii. Ch'w.. I'.iOi; (SO). 

 414; and Liclitwitz.'^^'' 



70 Hippocrates a])preciatpil tlie existence and iniijoiiaiicc <it" the mucoid liiii(lin<r 

 substance in urinarv eoneretions (Sdiepelniann. I?erl. kiin. Wocli., IHII (4S), 

 525 ) . 



VI "Die iiarnsteine," lU-ilin, .luiius Spriufior, IDll. 



