URINAKY CONSTITUENTS. 409 



AMOUNTS OF THE SEVERAL URINARY CONSTITUENTS PASSED IN 

 TWENTY-FOUR HOURS. (After PARKES.) 



By an average Per 1 kilo 



man of 66 kilos. of body-weight. 



Water 1500.000 grms. 23.0000 grms. 



Total solids 1.1000 



Urea 33.180 0.5000 



Uric acid 0.555 0.0084 



Hippuric acid 0.400 0.0060 



Kreatinin 0.910 0.0140 



Pigment, and other substances . . .10.000 0.1510 



Sulphuric acid 2.012 0.0305 



Phosphoric acid 3.164 0.0480 



Chlorine 7.000 0.1260 



(8.21) 



Ammonia 0.770 



Potassium 2.500 



Sodium 11.090 



Calcium 0.260 



Magnesium 0.207 



72.000 



343. The acidity of urine. The healthy urine of man is acid, owing 

 to the presence of acid sodium phosphate, the absence of free acid being 

 shown by the fact that sodium hyposulphite gives no precipitate. The 

 amount of acidity is about equivalent to 2 grammes of oxalic acid in 

 twenty-four hours, but the degree of acidity at any one time varies much 

 during the day, being in an inverse ratio to the amount of acid secreted by 

 the stomach ; thus it decreases after food is taken, and increases again as 

 gastric digestion comes to an end. It varies with the nature of the food ; 

 with a vegetable diet the excess of alkalies in the food, being secreted by 

 the urine, leads to alkalinity, or at least to diminished acidity, whereas this 

 effect is wanting with an animal diet, in which the alkalies are less abundant, 

 earthy bases preponderating. Hence the urine of carnivora is generally very 

 acid, while that of herbivora is alkaline. The latter, when fasting, are for 

 the time being carnivorous, living entirely on their own bodies, and hence 

 their urine becomes under these circumstances acid. 



The natural acidity increases for some time after the urine has been dis- 

 charged, owing to the formation of fresh acid, apparently by some kind of 

 fermentation. This increase of acid frequently causes a precipitation of 

 u rates, which the previous acidity, even after the cooling of the urine, had 

 been insufficient to throw down. After a while, however, the acid reaction 

 gives way to alkalinity. This is caused by a conversion of the urea into 

 ammonium carbonate through the agency of a specific " organized " ferment. 

 This ferment as a general rule does not make its appearance except in urine 

 exposed to the air ; it is only in unhealthy conditions that the fermentation 

 takes place within the bladder, and in such cases is due either to micro- 

 organisms introduced into the bladder from without, during the use of in- 

 struments for instance, or to the action of an unorganized ferment, secreted, 

 apparently by the walls of the bladder. 



344. Abnormal constituents of urine. The structural elements found in 

 the urine under various circumstances are blood, pus and mucous corpuscles, 

 epithelium from the bladder and kidney, and spermatozoa. To these may 

 be added the so-called " casts " which are either " epithelial casts," that is to 

 say, cylinders of more or less altered epithelial cells shed from the tubules, or 

 structureless, "fibrinous" casts, which are cylinders of peculiar material 

 moulded in the lumina of the tubules ; the exact nature of this material is 



