/ A'/N I A') CM. CI I.I 459 



The fatty acids coiisisti'd of stearic, j)aliiiitic, and pi'ohalily inyi-istic 

 aeid. 



Cholesterol calculi have been found in the urinary bladder in a 

 few instances, the cause being unknown. Horbaczewski ''- descril)es 

 one weij2;hiiig 25.4 ••■rains, found in a patient who had i)i-eviously had 

 cystine calculi; it contained 1)5.87 per cent, of cholesterol and but 0.55 

 per cent, of inorganic inatei'ial. (iall-stones have been known to 

 enter the urinary bladder through a fistula between the gall-bladdei- 

 and urinary bladder."" 



Fibrin "calculi," formed from blood-clots, often moi"e or less im- 

 pregnated with urinary salts, have occasionally been observed. Other 

 proteins may also form similar calculi.*^ 



General Properties of Urinary Concretions/"* — The hardness de- 

 ])ends partly upon the chemical composition of the calculus, hut more 

 upon the rate and condition of formation (Rowlands, Kahn). I'nder 

 comparable conditions it is said that those composed of amorphous 

 phosphates are the softest ; next come those with some admixture of 

 crystalline phosphates. IVate concretions are harder than these, but 

 are still softer than the uric acid and crystalline phosphate calculi. 

 Oxalates are usually the hardest, except for the rare crystallized 

 calcium carbonate stones. Cystine and amorphous concretions can 

 be scratched with the finger-nail, while even the hardest varieties of 

 calculi can be scratched with a wire nail. Genersich -" gives the 

 following degrees of hardness for different calculi: Cholesterol, 1.5- 

 1.6; ammonium urate, 2.5; soft phosphate (^Ig), 2.6; hard phos- 

 phate (Ca). 2.75: uric-acid stones (also salivary and prostatic calculi, 

 atheromatous patches, and phleboliths), 2.9; calcium oxalate (also 

 rhinoliths and lung stones), 3.3-3.5; calcium carbonate stones of 

 herbivora, 4.5. But the hardness or gross appearance of a urinary 

 calculus give little or no indication of its chemical composition. 



The rate of growth also varies according to composition, but is, of 

 course, mucli modified by other factors. Oxalate and urate stones 

 grow most slowly, phosphate stones most rapidly. A urate stone has 

 been known to increase by about two ounces during seven and one 

 half years, while a catheter fragment or other foreign body may be- 

 come covered with a crust several millimeters thick in a few weeks."" 



Spontaneous disintegration of urinary concretions is limited almost 

 solely to calculi composed entirely or largely of uric acid. Out of 121 

 cases collected by Englisch,*^ in all but 7 this was the case, these being 



82 Zeit. physiol. Cliem., 1804 (IS), Xir^. 



83 See Finsterer, Deut. Zeit. kliii. Chir., lOm; ISO), 4-i(). 



S4 See ]\Iorawitz and Adrian, Mitt. Orcnz. Med. u. Chir., l!li)7 i 17). .■)7!). 



f<"> Systems for i)rocediire in detenninin'/ tlie nature of luinarv ealeuli are given 

 by Hammarsten (Text-l)ooi< of Phvsiol. C'liem.) and bv Smith ( Reference Hand- 

 book of Med. Sci.). 

 ■ sfi Virehow's Arch.. 180.3 (131), 185. 



s" Zuckerkandl. Xothnasjel's System, vol. 10, pt. 2, p. 220. 



ssAroh. klin. Chir., 100.> (76), Or,l (elaborate review). 



