DIGESTIVE SYSTEM. 237 



attached to the superior or crescentic border of the hard palate, 

 the border formed by the palatine bones ; from which the velum 

 extends backward and downward as far as the larynx, and there 

 terminates over the epiglottis, in close apposition with that part, 

 in a loose semicircular edge. In consequence of the velum palati 

 being long enough to meet the epiglottis, ihe cavity of the mouth 

 has no communication with that of the nose — these two parts 

 forming a perfect septum between them ; hence it is that a horse 

 cannot respire and vomit by the mouth like a human being, in 

 whom the velum is so short that there is an open space left be- 

 tween it and the epiglottis, through which air or aliment can 

 pass either upward or downward. The soft palate is coniposed 

 of extensions of membrane from the nose and mouth, between 

 which is interposed a pale, thin layer of muscular fibres (described 

 at page 103, under the appellation oW-ircumJiexits palati). 



The velum performs the office of a valve : it prevents the food 

 in the act of swallowing from passing into the nose, and it con- 

 ducts the air from the windpipe into that cavity, without permit- 

 ting any to escape into the mouth. 



OF THE TONGUE. 



The tongue, the principal organ concerned in taste and deglu- 

 tition, is lodged in the mouth ; filling the interspace between the 

 branches of the inferior maxilla. 



Dup/iciti/. — Like the other organs of sense, it is double; beincr 

 composed of two parts, whose union is marked by a longitudinal 

 crease along its middle, the divisions having no vascular nor 

 nervous connexion, nor in fact any intercommunication whatever: 

 so that an animal has to all intents and purposes two tongues, 

 and apparently for the same reason that he has two eyes, two 

 ears, and two nostrils. Anatomy, as far as we can carry our 

 researches, demonstrates this ; perhaps we have no better proof 

 of it, however, than what happens in hemiplegia, a disease in 

 which only one half of the body is paralytic : under these cir- 

 cumstances, in the human subject, the patient can only see with 

 one eye, use one arm, and taste with but one (and that the cor- 

 respondent) side of the tongue. 



Division. — The tongue, in description, is commonly divided 

 into 7'oot, body, and apex : by the attachments of the two former 

 it is held in its situation ; the latter is loose and unconnected. 



Attachment. — At its root, it is deeply and firmly inserted by 

 several muscles which arise chiefly from the os hyoides and the 

 inferior maxilla: it is also connected with the pharynx, and with 

 the soft palate. From the sides of the lower jaw, separate layers 



