20 General P7nnciples of Veterinary Medicine. 



bronchi, it is called bronchitis ; when in the upper windpipe, 

 sore throat. Pleurisy is an inflammation of the membranous 

 sac we have described as the pleura. Asthma, roaring, thick 

 wind, broken wind, heaves and other disorders of the breath- 

 ins: arise from alterations in the nerves and tissues of these 

 organs ; while consumption, although a general disease of 

 the system, most frequently, both in men and horses, leads 

 early to a softening and breaking down of the substance of 

 the lungs. 



THE ORGANS OF DIGESTION. 



These include much more than the stomach and bowels. 

 The digestion of food really begins in the mouth, w^here it 

 is ground by the teeth and altered by the chemical action of 

 the saliva. Therefore we include under this heading, the 

 mouth, teeth, throat, gullet, stomach and bowels. 



It is in this part of the system that the herbivorous ani- 

 mals differ most from those which eat flesh onlv, and those 

 which eat both flesh and vegetable food. The chemical 

 processes which can convert dry hay to rich blood and firm 

 flesh are w^ondrously complicated and require an extensive 

 laboratory. This is furnished by a remarkable length of in- 

 testine and generally by several stomachs. In man the 

 intestines are six or seven times longer than his body ; in the 

 pig they are thirteen times longer ; in the sheep they are 

 twenty-eight times ; in the ox twenty-two times ; in the 

 horse but ten times the length of the body. Yet this gives 

 the horse an intestinal tube ninety feet long, and capable of 

 containing more than a barrel of fluid. 



The teeth, in both the horse and the ox, as in the child, 

 appear at first in a temporary set called "milk teeth,'' which 

 are followed by permanent ones, the change being completed 

 in both animals about the fifth year of life. The horse has 

 forty teeth, the ox and man thirty-two. As in the human 



