THE URINE. 331 



chemical constituents of the kidneys known at the present time 

 can, therefore, only have a secondary value. 



In the kidneys we find albuminous bodies of different kinds, 

 namely, globulin, albumin, and nucleoalbumin, also a gelatine- 

 forming and elastic substance, and lastly a body similar to mucin. 

 The question as to whether pure mucin really exists in the kidneys 

 has not been decided. The body similar to mucin, which is a 

 nucleoalbumin and which gives no reducible substance when 

 boiled with acids (LONNBERG), belongs chiefly to the papillae, while 

 the nucleoalbumin dissimilar to mucin belongs to the cortical sub- 

 stance. Fat only occurs in very small amounts in the cells of the 

 tortuous urinary passages. Among the extractive bodies of the 

 kidneys we find xanthin bodies, also adenin (KRONECKER), urea, 

 and traces of uric acid, glycogen, leucin, inosit, taurin, and cystin 

 (in ox-kidneys). The quantitative analyses of the kidneys thus far 

 made possess little interest. The quantity of water in human kid- 

 neys is 828.4 p. m. according to FRERICHS, and 834.5 p. m. according 



tO VOLKMANN. 



The fluid collected under pathological conditions, as in hydrouephrosis, is 

 thin with a variable but generally low specific gravity. Usually it is straw- 

 yellow or paler in color, and sometimes colorless. Most frequently it is clear, 

 or only faintly cloudy from white blood-corpuscles and epithelium-cells ; in a 

 few cases it is so rich in form-elements that it appears like pus. Albumin 

 occurs generally only in small amounts ; sometimes it is entirely absent, and 

 in a few rare cases the amount is nearly as large as in the blood-serum. Urea 

 occurs sometimes in considerable amounts when the parenchyma of the 

 kidneys is only in part atrophied ; in complete atrophy the urea may be 

 entirely absent. 



I. Physical Properties of Urine. 



Consistency, transparency, odor, and taste of urine. Urine is 

 under physiological conditions a thin liquid and gives, when 

 shaken with air, a froth which quickly subsides. Human urine or 

 urine from carnivora, which is habitually acid, appears clear and 

 transparent, often faintly fluorescent immediately after voiding. 

 When allowed to stand for a little while human urine shows a light 

 cloud (nubeculd) which consists of the so-called "mucus" and 

 generally also contains a few epithelium-cells, mucus-corpuscles, 

 and urate-granules. The presence of a larger quantity of urates 

 (uric-acid salts) renders the urine cloudy, and a clay-yellow, 



