LESSON 11. 



THE NOSTRILS AND LIPS. 



13. — The nostrils are those openings over the 

 muzzle through which the air has to pass on its 

 way to the lungs, and as a horse cannot breathe 

 through his mouth, all the air he breathes must pass 

 through his nostrils, so that they must be as wide 

 as possible. 



The nostrils are made up of muscle, which is 

 covered with skin and hair. 



The muscles are for the purpose of regulating the 

 width of the opening. It is plain that when the 

 horse is at rest he needs less air than when walk- 

 ing, trotting, galloping, or drawing a load, and so 

 only breathes about ten or twelve times a minute. 

 In doing so, it is quite plain that the opening of the 

 nostrils need not be so wide, as when at work he 

 breathes three times as quickly. The muscles are 

 thrown into action the moment the horse has to 



