URINE 



459 



phate" crystals. They may be differentiated from the phosphate 

 crystals by the fact that they are insoluble in acetic acid. 



The presence of calcium oxalate in the urine is not of itself a sign of 

 any abnormality, since it is a constituent of normal urine. It is increased 

 above the normal, however, in such pathological conditions as diabetes 



FIG. 134. CALCIUM OXALATE. (Ogden.) 



mellitus, in organic diseases of the liver, and in various other conditions 

 which are accompanied by a derangement of digestion or of the oxida- 

 tion mechanism, such as occurs in certain diseases of the heart and 

 lungs. 



Calcium Carbonate. Calcium carbonate crystals form a typical 

 constituent of the urine of herbivorous animals. They occur less fre- 



FIG. 135. CALCIUM CARBONATE. 



quently in human urine. The reaction of urine containing these 

 crystals is nearly always alkaline, although they may occur in ampho- 

 teric or in slightly acid urine. It generally crystallizes in the form 

 of granules, spherules, or dumb-bells (Fig. 135). The crystals of 

 calcium carbonate may be differentiated from calcium oxalate by the 



