URINE. 359 



to that which enters into the foundation of the hyaline form of 

 cast. In common with the hyaline type they are colorless, refractive 

 bodies but differ from this form of cast in being, in general, of 

 greater length and diameter and possessing sharper outlines and a 

 light yellow color (Fig. 113, p. 357). Such casts occur in several 

 forms of nephritis but do not appear to characterize any particular 

 type of the disorder except amyloid disease, in which they are rather 

 common. 



(g) Pus Casts. Casts whose surface is covered with pus cells 

 or leucocytes are termed pus casts (Fig. 1 1 1, p. 356). They are fre- 

 quently mistaken for epithelial casts. The differentiation between 

 these two types is made very simple however by treating the cast 

 with acetic acid which causes the nuclei of the leucocytes to become 

 plainly visible. The true pus cast is quite rare and indicates renal 

 suppuration. 



Cylindroids. These formations may occur in normal or patho- 

 logical urine and have no particular clinical significance. They 

 are frequently mistaken for true casts, especially the hyaline type, 

 but they are ordinarily flat in structure with a rather smaller diam- 



FIG. 115. 



CRENATED ERYTHROCYTES. 



eter than casts, may possess forked or branching ends and are not 

 composed of homogeneous material as are the hyaline casts. Such 

 " false casts " may become coated with urates, in which event they 

 appear granular in structure. The basic substance of cylindroids is 

 often the nucleoprotein of the urine (see Fig. 114, page 358). 



