354 



PHYSIOLOGICAL CHEMISTRY. 



structure and as the process of degeneration continues the cell out- 

 line ceases to be visible, the nuclei fade, and jinally only a mass of 

 debris containing isolated nuclei and an occasional cell remains. 



It is frequently rather difficult to make a differentiation between 

 pus corpuscles and certain types of epithelial cells which are similar 

 in form. Such confusion may be avoided by the addition of iodine 

 solution (I in KI), a reagent which stains the pus corpuscles a deep 

 mahogany-brown and transmits to the epithelial cells a light yellow 

 tint. The test proposed by Vitali often gives very satisfactory re-, 

 suits. This simply consists in acidifying the urine (if alkaline) 

 with acetic acid, then filtering, and treating the sediment on the 

 filter paper with freshly prepared tincture of guaiac. The presence 

 of pus in the sediment is indicated if a blue color is observed. 

 Large numbers of pus corpuscles are present in the urinary sedi- 

 ment in gonorrhoea, leucorrhosa, chronic pyelitis and in abscess of 

 the kidney. 



FIG. 107. 



HYALINE CASTS. 

 One cast is impregnated with four renal cells. 



Casts. These are cylindrical formations, which originate in the 

 uriniferous tubules and are forced out by the pressure of the urine. 

 They vary greatly in size but in nearly every instance they possess 

 parallel sides and rounded ends. The finding of casts in the urine 



