URINE 495 



Urostealith Calculi. This form of calculus is extremely rare. 

 Such concretions are composed principally of fat and fatty acid. When 

 moist they are soft and elastic, but when dried they become brittle. 

 Urostealiths are generally light in color. 



Fibrin Calculi. Fibrin calculi are produced in the process of blood 

 coagulation within the urinary tract. They frequently occur as nuclei 

 of other forms of calculus. They are rarely found. 



Cholesterol Calculi. An extremely rare form of calculus somewhat 

 resembling the cystine type. 



Indigo Calculi. Indigo calculi are extremely rare, only two cases 

 having been reported. One of these indigo calculi is on exhibition in 

 the museum of Jefferson Medical College of Philadelphia. 



The scheme, proposed by Heller and given on page 494, will be 

 found of much assistance in the chemical examination of urinary calculi. 



