THE URINE 



333 



Chlorine is supplied by the chlorides of the food. The pro- 

 portion of chlorides in the food of herbivora is not very high ; 

 the amount excreted by horses, combined with sodium, was 

 found by us to equal a daily excretion of 5-5 grammes (85 J grains) 

 of common salt. Salkowski places it much higher — viz., about 

 27 grammes (f ounce) daily. 



Phosphoric Acid, though existing largely in food such as oats, 

 passes off almost wholly by the alimentary canal. Sometimes 

 only traces are to be found in the urine of herbivora ; at others 

 the amount is marked, but never considerable. Work does not 

 influence its production. In the urine of carnivora the phos- 

 phates are an important constituent. They exist in the urine 

 in two forms — viz., alkaline phosphates, such as phosphate of 

 sodium or potassium, and 

 earthy phosphates, such as 

 phosphates of calcium and 

 magnesium ; these triple 

 phosphates are common as 

 a microscopical object in the 

 decomposing urine of the 

 horse, though trifling in 

 actual amount (Fig. 104).^ 

 The phosphates are derived 

 from the food and tissues. 

 According to Munk, if there 

 is an abundance of lime salts 

 in the diet, as in vegetable 

 food, the phosphates are not 

 eliminated to any extent by 

 the kidneys, for the reason 

 that they combine in the 



intestinal canal with lime and magnesia, and pass off by that 

 channel ; if, on the other hand, there is but little lime and mag- 

 nesia in the intestines, the phosphates are united to soda and 

 potash, pass into the blood, and are eliminated by the urine. 

 In febrile conditions in the herbivora phosphates appear in the 

 urine in marked amounts. 



The Reaction of the urine of herbivora is alkaline, the 

 alkalinity being due to carbonate of potash. The urine of all 

 vegetable feeders is alkaline, owing to the excess of alkaline 

 salts of organic acids contained in the food, such as malic, citric, 

 tartaric, and succinic. During their passage through the body 

 these salts are oxidised into carbonates, and appear as such 

 in the urine, where they produce considerable effervescence on 

 the addition of an acid. The nature of the food influences the 

 reaction. It is stated that a horse fed on perennial rye grass 



Fig. 104. — Crystals of Triple Phos- 

 phate (Funke). 



