URINARY APPAR.\TUS. 171 



Severe febrile diseases. 



Formation of large quantities of exudates in the pleural 

 and peritoneal cavities. 



Weak heart and resulting diminished pressure. 



Acute and some forms of chronic nephritis. 



An increase in the quantity of urine occurs in: 



Diabetes insipidus [polyuria] (very marked) diabetes 

 mellitus (which is rare), the daily average may be 40 liters. 



Most forms of chronic nephritis. 



During reabsoption of profuse exudates and in the criti- 

 cal stage of severe infectious diseases. 



b. The color. The normal pigments in urine have not 

 yet been thoroughly studied ; although a number of them 

 are known to exist, only one has been identified, viz. urobilin 

 which is a product of bilirubin and is absorbed from the 

 intestine. The color of normal urine is more or less yellow, 

 increasing in darkness as the amount of urine decreases, and 

 vice versa. In disease the color may become lighter or 

 darker. We distinguish: yellow (pale yellow, light yellow, 

 yellow), red (reddish yellow, yellowish red; red), and brown 

 (brownish red, reddish brown, and blackish brown) urine. 

 Other shades can also be recognized now and then. 



Pale, water-colored urine always occurs in polyuria 

 (physiological or critical polyuria, diabetes). 



Red urine is produced by admixture of blood, hemaglo- 

 bin or methemaglobin. The particular cause in each case 

 must be determined with the aid of the microscope. 



Greenish yellozv or brozvnish yellozv urine or yellowish 

 green foam is produced by bile-pigments. 



Dark eolored urine (dark yellow or dark brown) is ob- 

 served in all cases where the quantity has been reduced (con- 

 centrated), but it may also be due to admixture of blood. 



Color due to medicines: carbolic acid, black; aloes and 

 rhubarb, brownish red. 



c. Transparency of urine. Normal urine of the horse 



