118 ON RESPIRATION, 



nose, on ^^4lich account his nostrils are wider in 

 proportion than in other animals, which, when 

 urged by exercise, or otherwise when requiring 

 more air, open their mouths for its freer ad- 

 mission. 



The horse has a peculiarity in the formation 

 of his nostrils which deserves notice, each nos- 

 tril being divided by a septum, on one side of 

 which is the canal which communicates with 

 the throat and lungs, on the other side of the 

 septum is a canal or sac, which may be called 

 the false nostril, which reaches upwards about 

 four or five inches, and is imperforate {Vide plate 

 9, letter II) ; but for about two inches of that 

 depth the septum is slit up, and the edges of 

 the slit are fringed with short hairs ; the parti- 

 cular use of this conformation has not yet been 

 pointed out, and remains a problem for the 

 physiologists. AVhen the horse inspires, this 

 part is filled with air, which remains stationary 

 until the act of expiration, at which time it 



passes 



