522 EXCREMENTS. 



exclusively of acid ammonium urate. The urine of 

 herbivorous mammalia, as, for example, that of horses 

 and cattle, is usually alkaline; contains urea, but 

 little uric acid ; on the other hand, a large quantity 

 of hippuric acid (p. 336), and frequently phenol (p. 

 290) ; further, potassium bicarbonate and lactate, but 

 no alkaline phosphate ; it deposits a sediment of cal- 

 cium and magnesium carbonates. The urine of suck- 

 ing calves contains allantoine (p. 243) and no hip- 

 puric acid. The urine of insects contains uric acid 

 and guanine (p. 247). 



20. Excrements. 



Normal human excrements contain about 25 per 

 cent, of solid ingredients, and of these, on an average, 

 6.5 per cent, are inorganic salts ; the rest is water. 

 Their nature varies according to the food. The ash 

 of human excrements contains 25-30 per cent, of solu- 

 ble salts, and about 30 per cent, of phosphoric acid in the 

 form of sodium, potassium, calcium, and magnesium 

 salts. The excrements of herbivorous animals contain 

 all the phosphoric acid which is separated from the 

 organism, as this acid is entirely wanting in the urine. 

 Human excrements, the organic ingredients of which 

 soon begin to undergo decay, contain mucus, undi- 

 gested remnants of food, altered ingredients of the 

 bile (taurin, cholesterin), a peculiar, crystallizing com- 

 pound, excretin, containing sulphur, and but little 

 known and undetermined matters. The excrements of 

 cattle contain a large quantity of undigested cellulose, 

 colored green by chlorophyl. 



