THE KIDNEYS. 279 



situated under the loins. Their form is like that of a 

 kidney bean. The right kidney lies most forward, and is 

 placed under the liver ; the left one lies more backward, 

 rather behind the stomach and spleen. They lie behind 

 and are concealed by the intestines, consequently upon 

 dissection they are not visible until the intestines are 

 removed, as will be seen by plate ix., fig. 1. In fig. 2 these 

 are removed, and the kidneys, d, d, are exposed, as well as 

 other organs which occupy the chest and abdomen. The 

 chief function of the kidneys is the secretion of the urine, 

 and carrying ofi" an ingredient which enters into its com- 

 position, called the urea, a substance which, if allowed to 

 circulate with the fluids, would prove poisonous. To each 

 of the kidneys a large artery runs, which conducts nearly a 

 sixth part of the blood of the body to them. These branch 

 off into innumerable minute fibres, which ramify every 

 portion of the substance of the kidney, and by this means 

 the watery portions are separated from the blood, and con- 

 ducted to the bladder. The urine varies more in its quan- 

 tity and quality in the horse than in any other animal witJi 

 which we are acquainted, and hence the necessity of attend- 

 ing to its appearance and composition during disease ; 

 because attention to this enables the veterinarian to detect 

 the disease, and also to judge the quantity of medicine 

 which may prove beneficial to the animal. In the applica- 

 tion of these much good or much evil may be the result. 

 Ignorant ostlers, seeing the effects of nitre in promoting 

 staling and also in purifying the urine, are too prone to use 

 it with indiscretion. These diuretic medicines, if used in 

 too great quantities, stimulate the kidneys to separate more 

 of the watery fluid than they do in a natural and healthy 

 condition, and the effect is to lessen the quantity of blood. 

 Although this property in nitre is advantageous in many 



