480 PHYSIOLOGICAL CHEMISTRY. 



E. 1, Leucin, or amido-caproic acid, C 6 H n (NH 2 )O 2 ; and 2, Tyrosin, 

 C 9 H U NO 3 , are but rarely met with in urinary deposits. Leucin is 

 found either as rounded lumps, showing but little crystalline struc- 

 ture, or as spherical masses, exhibiting fine radial striation. Tyrosin 

 appears generally in fine, long, silky needles, forming bundles or 

 rosettes. 



F. Oystin occurs occasionally as a grayish, crystalline deposit, 

 forming transparent six-sided plates ; it also occurs in calculi. The 

 latter may be recognized by the above-mentioned chemical properties 

 or by dissolving a little in hydrochloric acid and neutralizing with 

 ammonia, when cystin is reprecipitated and shows the characteristic 

 six-sided plates under the microscope. 



G. Magnesium-ammonium phosphate, or triple phosphate, MgNH 4 - 

 PO 4 .6H 2 O, is found generally in triangular prisms with bevelled 

 ends, as shown in 1, but sometimes also in star-shaped, feathery 

 crystals, represented in 2. 



H. Calcium phosphate, Ca 3 (PO 4 ) 2 , is most frequently found in 

 amorphous globules, but also crystallized either in prisms, 1, or in 

 '* wedge-shaped " crystals, 2. 



I. Calcium oxalate, CaC 2 O 4 , occurs either in quadratic octohedra 

 with brilliant refraction, 1, or sometimes in the shape of "dumb- 

 bells," 2. 



J. Blood corpuscles appear under the microscope as reddish, circular 

 disks, sometimes laid together in strings. If seen in profile, they 

 appear biconcave. 1, shows the corpuscles in a fresh condition; 2, 

 as generally seen in urine. 



K. Mucus and pus are often difficult to distinguish from each 

 other under the microscope, as they both appear as little granular 

 globules, varying somewhat in appearance with the reaction of the 

 urine. Pus is rendered slimy, ropy, viscid, and tenacious by the 

 addition of caustic potash. 1, shows globules of mucus ; 2, of pus; 

 and 3, of pus treated with acetic acid, which clears up the granular 

 globules with the appearance of a nucleus. 



L. Hcemin crystals. The formation of these crystals often serves 

 to recognize blood, and is accomplished by mixing the latter on a 

 glass slide with a trace of sodium chloride and a drop of glacial 

 acetic acid and warming gently, when the characteristic crystals will 

 appear. By repeating the process several times, larger and better- 

 developed crystals are obtained. 



M. 1, Hyaline casts; 2, Granular casts. Urinary casts are tube- 

 like cylinders, often found together with blood and pus corpuscles, or 



