ON RESPIRATION 117 



k. Immediately behind the velum palati is 

 situated a cartilaginous substance of a triangular 

 pointed shape, having its base attached to the 

 root of the tongue in the horse, which is deno- 

 minated the Epiglottis. Its oflice is to cover 

 the orifice of the trachea or windpipe in the ac- 

 tion of deglutition. The epiglottis is constant- 

 ly elevated by its own elasticity, and never co- 

 vers the trachea, except at the moment when 

 it is pressed downwards by the food passing 

 over it. 



When it is elevated, it turns back with its 

 upper surface immediately against and behind 

 the velum palati, vv'ith which it enters into close 

 contact in such a manner, that it forms a valve, 

 preventing the return of air, or any substance 

 whatever, through the mouth (Fide plate 9> 

 letters C and E). Thus it may always be observ- 

 ed, that the horse, even during the most violent 

 exertions, never opens his mouth for the purpose 

 of breathing, but performs it solely through his 

 I 3 nose, 



