URINE AND ITS CONSTITUENTS. 



741 



glass or whirled in the centrifuge for a few minutes ; when the 

 sediment has collected at the bottom the supernatant urine may !><> 

 decanted, or the sediment may be taken out by means of a pipette 

 for examination. 



Sediments are either organized or unorganized. To the first 

 belong: mucus, blood, pus, fat, urinary casts, epithelium, sprrmato- 

 zoids, fungi, infusoria, etc. ; to the second belong : uric acid, urates, 

 calcium oxalate, phosphate, or carbonate, magnesium-ammonium 

 phosphate, cystine, hippuric acid, etc. 



The chemical examination of any urinary sediment should always 

 be preceded by a microscopical examination, which latter is in many 



FIG. 76. 



Various forms of uric acid crystals. (Finlayson.) 



cases the only way of determining the nature of the sediment, espe- 

 cially of the organized substances. 



Organized sediments. Red blood-corpuscles appear under the 

 microscope as reddish, circular disks, sometimes laid together in 

 strings. If seen in profile, they appear biconcave. 



Pus cells (leucocytes) appear as round granular cells, in which the 

 nucleus frequently is not made out until dilute acetic acid is added. 



Epithelial cells, from the urinary tubules, ureter, bladder, vagina, 

 etc. Their place of origin is frequently difficult to determine. 



Casts. Hyaline, waxy, finely granular, coarsely granular, pus 

 casts, blood casts, epithelial casts. 



Unorganized sediments, (a) In acid urine. Uric acid is deposited 

 in colored crystals from acid urine ; it is not dissolved by heat, nor 



