DISEASES OF RESPIRATORY PASSAGES AND ORGANS. 115 



east and west sides, were composed of brick, and the remainder 

 of boards, with joints battened. On the south, east, and west 

 skies were glass windows ; on the north side a door opened into 

 the vegetable cellar, and on the roof there was a sky-light. A 

 stairway led to the hay-loft above, another to the manure cellar 

 below, both closed by doors. The manure cellar was eight feet 

 deep, and extended under the whole room. In the winter and 

 spring of 1859 were confined forty head of cattle, arranged on 

 three sides, with their heads toward the center ; and within that 

 center was another square, containing animals, so arranged that 

 almost all were brought face to face. The manure cellar, about 

 this time, contained from fifty to one hundred cords of manure, 

 with from ten to twenty hogs in it. " This," says Mr. Chenery, 

 " was my condition in the beginning of the year 1860. I had 

 buried nearly half of my herd. I had experimentally acquired 

 a knowledge of the fact that, in order to keep animals alive and 

 in health, it was absolutely necessary that they should be supplied 

 Mith pure air as well as with good food and pure water." 



So far as the direct or indirect causes of pneumonia are con- 

 cerned, we may safely infer that crowding and a bad system of 

 ventilation includes them all. Yet, among horses, this disease 

 often originates as the consequence of laborious work and feats 

 of speed, which produces rapid and sometimes distressing respira- 

 tions; but among cattle, whose powers of speed and endurance 

 are not often put to the test, and whose natural respirations are 

 slower, we infer that impure air, and perhaps exposure, too, are 

 more operative than action or ill-usage. 



The stimulating and morbid action of an impure atmosphere 

 may produce a disease of this character by its irritating effects on 

 the highly vascular membrane which lines the bronchi and air- 

 cells. But then we all know that impure air fails to decarbonize 

 the blood ; hence it is rendered unfit to enter the system. It has 

 been noticed, however, by the drovers of the East, that when cat- 

 tle have been driven a long distance without food, and in tem- 

 pestuous weather, they are apt to become the subjects of diseased 

 lungs. Fortunately for the poor brute, pneumonia is not so pain- 

 ful as bronchitis, pleurisy, or laryngitis ; and having passed through 

 the acute stage, which is usually brief, it assumes a mild or sub- 

 acute form, and ends in altered structure of the lungs, known as 

 induration (hardening) or hepatization (liver-like), or it may end 



