THE VklNE 335 



the diet being moderately nitrogenous, but in individual instances 

 very much more than this may be met with — viz., 6 to n litres 

 (12, 15, or even 20 pints). 



Horses at work excrete less urine than those at rest, no doubt 

 owing to the loss by the skin. In winter, in consequence of the 

 lessened action of the skin, more urine is excreted than during 

 summer. 



The Odour of urine is said to be due to certain aromatic sub- 

 stances of the phenol group. Perfectly fresh urine has commonly 

 a most distinct though faint smell of ammonia. This may be 

 due to fermentative changes occurring in the urea before the 

 urine is evacuated. The normal fluid is always turbid, some 

 specimens more so than others ; very rarely is it clear, and then 

 only for a short time. The turbidity is due to the amount of 

 suspended carbonate of lime and magnesia it contains ; as the 

 urine cools, particularly if it undergoes ammoniacal fermentation, 

 the amount of turbidity becomes intense (see p. 331). 



The Consistence of the fluid depends upon sex, and perhaps 

 on the season. It is certain that some mares excrete a glairy, 

 tenacious fluid which, owing to the amount of mucin it contains, 

 can be drawn out in strings ; it is very common to rind it as thick 

 as linseed oil, and very rare to find it fluid and watery. During 

 oestrum the urine is of the consistence of oil. On a diet of oats 

 and no hay, the urine may be so mucinous as to pour like 

 white of egg. 



The Colour of urine is yellow or yellowish-red, rapidly turning 

 to brown, the dark tint commencing on the surface of the 

 fluid, and gradually travelling into its depth. The cause of 

 the colour on standing is due to the oxidation of pyrocatechin 

 (see p. 330). 



The Total Solids consist of organic and inorganic matter, 

 of which, on a mixed diet, 142 grammes (5 ounces) are organic, 

 and 85 grammes (3 ounces) inorganic ; the quantities are liable 

 to great variation, sometimes being found greatly in excess of 

 that mentioned. The total solids are considerably affected by 

 the diet ; E. Wolff * found that when he reduced the hay and 

 increased the corn ration, the solids in the urine decreased, 

 whereas on a diet consisting principally of hay and but little 

 corn the solids increased ; for example — 



On a diet of 8 kilogrammes of hay and 2 kilogrammes of oats 



there were 566 grammes of total solids. 

 On a diet of 4 kilogrammes of hay and 6 kilogrammes of oats 



there were 460 grammes of total solids. 



The composition of the mineral solids is given in the following 

 * Ellenbcrger. • 



