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 off 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 witli 
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 
