METABOLISM 



243 



A complete list of all the substances found regularly in normal urine 

 would be very long, but among them are the following dissolved in the 

 water: Urea, uric acid, hippuric acid, creatinin, urochrome, urobilin, 

 uroerythrin, hematoporphyrin, chromagens, dextrose, isomaltose, vola- 

 tile fatty acids, xanthin, heteroxanthin, paraxanthin, hypoxanthin, 

 guanin, adenin, amido-acids, phenol-sulphuric acid, cresol-sulphuric 

 acid, etc., inosit, glycuronic acid, acetone, cholesterin, lecithin, sulphates 

 and acid-sulphates of sodium and potassium, phosphates of sodium, 

 potassium, calcium, and magnesium, chlorides of sodium, calcium, and 

 potassium, sulphocyanide of potassium, lactic acid, iron, hydrogen 

 peroxide, carbon dioxide, ammonia, and enzymes. Most of these would 

 be reported in chemical analyses as traces merely. The important and 

 measurable constituents are given in the following table : 



AVERAGE COMPOSITION IN GRAMS OF A DAY'S URINE. 



* Calculated as the metal and not as the oxide. 



The above table (altered from one by MacLeod after analyses given 

 by Parkes and Bunge) shows how wide is the variation in the composi- 

 tion of the urine with different diets. The urea, for example, in 1920 c.c. 

 of urine excreted on a bread-diet was little more than 30 per cent, of 

 its amount when all the food was meat, although in the latter case the 

 amount of the urine was 248 c.c. less in quantity. This is a constant 

 variation, for, other things equal, a meat-diet gives rise to a small amount 

 of concentrated urine, the water-producing factors of the mixed and 

 largely carbonaceous diets not being present. The average amount 

 secreted is about 1500 c.c. (ranging from 1200 to 1700 c.c.), or about 

 1 c.c. each hour for every kilo of body weight. Women excrete about 200 

 c.c. less than men daily and children per kilo of weight 70 per cent, 

 more. The amount is increased by drinking liquids or eating a large 

 amount of proteid, by lack of respiratory oxygen, rise of renal blood- 

 pressure, ingestion of a large amount of "extractives," vaso-constriction 

 in the skin, various drugs, diabetes, and by some nervous derangements. 



