RENAL SECRETION. 639 



Horses' urine contains urea and hippuric acid in inverse proportions. 

 When one increases the other decreases, the amount of the latter depend- 

 ing on the amount of green forage or hay or straw, the former on the 

 amount of oats, grains, roots, etc. The percentage of urea in ordinary 

 feeding varies from 2.5 to 4.0 per cent. 



Very large amounts of aromatic sulphur compounds are present, 

 especially of phenol and indican. The former, with hippuric acid, causes 

 the peculiar odor; the latter, the colors seen in the film which forms, 

 when exposed to the atmosphere. Brenzcatechin is also present and is 

 the cause of the brown color which forms on standing. 



CaCOj, is the principal salt, and is rapidly deposited as a sediment. 

 Sulphur compounds are found in varying amounts. Phosphates, except 

 in abundant feeding with grains, are only present in traces. The amount 

 of urine is only about five to six liters daily, evacuated in three to four 

 portions, since a large amount of water is lost through the skin in 

 perspiration. 



The Urine of the Ox. — The amount of urine depends not only upon 

 the amount of water taken, but especially on the amount of nitrogenous 

 food. Thus, when the diet has been poor in nitrogen, the amount of 

 urine passed daily will vary from 9.1 to 12.6 kilos, and when a richer 

 nitrogenous diet is given the amount will be increased to from 16.3 to 

 16.8 kilos. This is, without doubt, partly to be attributed to the larger 

 amount of water required in a rich, nitrogenous diet. The evacuation 

 of the urine occurs from eight to ten times daily, averaging about one 

 kilo each time. The character of the food exerts the greatest influence 

 on the reaction of the urine. Fodder rich in alkaline carbonates or com- 

 pounds of the organic vegetable acids occasions an alkaline reaction of 

 the urine. The amount of carbonates in the solids of the urine is 

 directly in proportion to its alkalinity. Carbon dioxide is especially 

 abundant when fed on beets, clover, hay, or bean-straw, when it may 

 amount to 10 or 12 per cent. When fed with oat-straw or barley -straw, 

 the carbon dioxide sinks to from 3 to 6 per cent. Exclusive feeding with 

 wheat-straw is said to cause an acid reaction of the urine on account of 

 the poverty of carbonates and vegetable acids. The total amount of 

 solids in the urine averages about 6.8 per cent., composed of — 



C, . 27.8 to 53.1 per cent. 



H, . ... . 3.5 to 6.9 



N, . 8.9 to 33.6 



O, . 15.6 to 50.2 



The quantity and quality of the organic matter in the urine varies 

 greatly according to the food, varying between 4.2 to 11.3 per cent., and 

 is especially dependent upon the digestible, nitrogenous food-stuffs. The 

 non-nitrogenous food-stuffs are without influence on the organic urine 



