116 ON RESPIRATION. ^ 



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The posterior part of the mouth or throat 4 

 of the horse is so constructed a- almost entirely ' \ 

 to prevent the return of air thiough its cavity, 1 

 or, in other words, precludes expiration. Thus, I 

 although he can receive air through his mouth, i 

 he returns h only through his nose. Hence \ 

 the horse always manifests great uneasiness 

 when he is held by the nostrils, as under those ! 

 circumstances he naturally dreads suffocation. | 



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From the posterior part of the roof of the 

 mouth a membrane descends, the extreme edge 

 of which lies on the surface of the tongue. 

 This membrane is called Velum palati, and one 

 of its uses is to prevent the food and water from 

 returning through the nose in their passage to 

 the stomach. This membrane, in the human 

 being, terminates in a descending point, termed 

 the Uvula; but in the horse it preserves one re- 

 gular form, on which account the animal has 

 no uvula, the whole of the velum reaching 

 down to the root of the tongue, and resting upon 



it. 



