ANATOMICAL CONSIDERATIONS. 29 



tenance into its proper receptacle. However, upon inquiry, tlie reader 

 will discover these provisions, which appear at first glance to be ranged 

 against the entrance of nutriment, are in reality only so many elaborate 

 protections, all tending to the comfort and well-being of the animal. 



The soft palate so effectually closes the posterior of the mouth as to 

 prevent that cavity from being employed to modulate the voice, though 

 such a pecuharity does not distinguish all the equine tribe. Everybody 

 must have remarked the bray distend the jaws of an ass, whereas the 

 neigh flutters only the nostril of the horse, the different channels through 

 which the sound has to emerge fully accounting for the marked contrast 

 which is conspicuous in the voices of the animals. Moreover, the horse 

 does occasionally vomit ; but, save when the organization is disturbed 

 by the agonies of death, the voided matter is generally ejected through 

 the nostrils. 



However, the reader will perhaps best understand how the apparently 

 closed cavity is rendered subservient to its uses by the process of deglu- 

 tition being described. A portion of food is bitten off by the incisors ; 

 the substance is, by the action of the tongue, next passed to the molars, 

 or is placed between the grinding teeth. There it is thoroughly com- 

 minuted. While this is being performed, the saliva is secreted and min- 

 gled with the mass, so as to render it quite soft or pultaceous. In- this 

 state it is formed into a pellet, and is then pressed by the tongue against 

 the palate or roof of the mouth. The morsel, bemg now round and 

 soft, is afterward, by a more energetic contraction of the tongue, driven 

 against the pendulous palate, which seemingly closes the posterior of 

 the orifice. 



The last organ lies in that direction which enables it to offer a formi- 

 dable resistance, especially when supported by the base of the tongue, to 

 any substance proceeding from the stomach. In the contrary direction 

 it is only held down by the epiglottis ; that comparatively feeble body is 

 forced to yield before the greater contractile power of the lingual organ. 

 The epiglottis flies forward, covering the opening to the larynx, in which 

 position the posterior cartilages or the aretenoids also fold over the more 

 forward protector. A secure floor is thus formed, preventing anything 

 from falling into the windpipe, where intrusion of the smallest substance 

 would provoke the most alarming spasm ; while a roof to the passage is 

 also made by the raised, soft palate, whereby the nasal chambers are 

 protected from the encroachment of undigested matters. 



A safe way being thus provided, the pellet is shot into the pharynx, 

 which, independently of the will, immediately contracts upon any sub- 

 stance coming within its reach, and drives the morsel into the oesophagus 

 or gullet. The tube, surprised by the presence of the morsel, is obliged 



