THE STABLE 77 



When this is not easy to affect, then they should be as 

 near the ceiling and as far from the horse's nostrils as 

 possible. They may be made oblique, which will give exit 

 to the current of heated air, and protect the stable from 

 rain and wind. But as, owing to the construction and 

 confined situation of some stables, or from floors above, 

 these openings cannot be made, then small tubes may be 

 opened into the stable, in the ceiling, or as near its height 

 as possible. These may be carried into a flue to the top of 

 the building, or outwardly with perforations in the wall. 



We cannot quit the subject of ventilation without 

 endeavouring to impress on the reader the importance, nay, 

 the indispensable necessity of a clear comprehension of its 

 influence on the animal economy. The respiration must 

 not be considered, as is too often taught in elementary 

 handbooks, as a mere chemical process — a simple combustion 

 in the lungs, in which the oxygen of the inspired air unites 

 with the carbon of the blood, to form carbonic acid, and 

 then be expelled from the system. Respiration is a function 

 much more complex ; it consists of absorption and exhalation 

 — the attributes of all living and breathing beings: and, 

 further, in the assimilation of two constituents of the air, 

 oxygen and azote. The living principle is, then, 'par excel- 

 lence, the breath, and through that the blood. The vital 

 principle, then, is more readily acted on by the lungs 

 receiving impure air, instead of its natural food, pure air, 

 than by any other circumstance whatever. The lungs, let 

 it never be forgotten, are a second stomach, and the respira- 

 tion but another form of digestion. When food enters the 

 stomach, its nutrient parts are separated and converted into 

 chyle ; when air enters the lungs, its vital properties are 

 separated to repair the waste and purify the blood which 

 builds up the animal system. If the stomach receive im- 

 pure and unwholesome food, disease is induced ; if the lungs 

 receive efiiuvia from decayed animal or vegetable matter, 

 instead of pure atmospheric air, then also the system becomes 

 diseased. 



Glanders and farcy may be adduced as proving this fact. 

 Both these diseases are originated by breathing aerial 

 poisons, and the disease of the blood is the cause of the 

 disease of the solids. When a horse is infected with the 

 disease called the glanders, he will be found also farcied. 

 The poison at first develops a local disease, which after a 



