INTERNAL ORGx\NS. 15 



a very complete valve, which opens downward 

 only, thereby preventing the return of any 

 thino^ throus^h the mouthy either from the luno-s 

 or stomach : thus we find that a horse breathes 

 only through his nose, except in coughing, by 

 which the valve is so derancred as to allow the 

 air, so thrown out from the lungs, to pass 

 through the mouth. 



In the case of vomiting I have just men- 

 tioned, the contents of the stomach were at 

 "first observed to pass through the nose ; at 

 length, by a violent cough, the valve was de- 

 ranged, and a considerable quantity of fluid, 

 mixed with masticated hay and oats, was eva- 

 cuated by the mouth. 



That part of the stomach where the ceso- 

 phagus terminates is called the cardiac orifice ; 

 and that where the intestines begin is termed 

 pylorus. 



The intestines or bowels consist of one very 

 long tube, which terminates at the mius. 



In the horse the intestines measure nearly 

 thirty yards; but being convoluted in order to 

 adapt them to the cavity in which they are 

 placed, they have the appearance of several 

 distinct parts. 



The internal surface of a horse's intestinea 



