198 CLINICAL DIAGNOSTICS. 



i. Red blood corpuscles, when found in the urine, 

 have lost most of their coloring matter, are pale and swollen. 

 Those coming from the upper portions of the urinary tract 

 have undergone these changes to a greater extent than those 

 coming from the lower portions. Thorough admixture of red 

 corpuscles with the urine, thus retarding sedimentation of the 

 former, points to renal hemorrhage ; blood casts always point 

 to renal hemorrhage. Large masses or clots of blood, not thor- 

 oughly mixed with the urine, come from the bladder. An 

 admixture of blood with the urine (hematuria) occurs in: 



1. Diseases of the kidneys: injuries, hem- 

 orrhagic nephritis, embolic nephritis ; 



2. Diseases of the urinary tract : pyelonephritis, cys- 

 titis, red water of cattle, cystic calculi, cystic tumors, in- 

 juries of the urethra. 



k. Urinary casts are cylindrical bodies that were 

 molded in the lumen of the uriniferous tubules. In the urine 

 of the horse we find similar structures under normal condi- 

 tions ; they consist of strings of mucus of variable thickness, 

 sometimes macroscopically visible and granulated with de- 

 posits of amorphous carbonate of lime. Addition of acetic 

 acid causes the granules to disappear with the formation of 

 CO,. In acid urine we find uric acid salts instead. These so 

 called granule casts, lime casts, or cylindcroids have noth- 

 ing whatever in common with true urinary casts. They 

 are especially common in the transition stage from oliguria to 

 polyuria. 



The true urinary , casts are distinguished as follows : 



1. Hyaline casts, slender, transparent, homogeneous 

 bodies of various sizes and not sharply defined contour. They 

 are rare, occur in health as well as in disease, are of no diag- 

 nostic importance and their origin is unknown. 



