198 ANATOMY OF THE HEAD. 



THE PHYSIOLOGY OF THE MOUTH AND THE SENSE OF TASTE. 



Taste appears to be derived from contact with the large 

 papillae at the back of the tongue. Taste does not exist 

 there is every reason to conclude, when the mouth and 

 food are perfectly dry ; but then it is difficult to have the 

 mouth in such a state as to preclude the possibility of 

 saliva being secreted ; and with regard to food, even the 

 captain's biscuit contains much moisture. Yet liquids are 

 tasted much sooner than solids ; which last are not gene- 

 rally relished, until by the process of mastication they have 

 been thoroughly moistened with sahva. Thus moisture 

 can either be taken in with the food, or be contributed by 

 the glands proper to the mouth after the food has been 

 taken in ; for in one way or the other fluid must be mingled 

 with the substance eaten before taste can exist. The 

 tongue, which is the organ of taste in most vertebrated 

 animals, possesses an exquisitely modified sensibility, and 

 in brutes is endowed also with a salutary instinct. In man, 

 civilization, by heightening the intellectual, has weakened 

 the instinctive powers, if they ever existed. Taste w^as 

 given to brutes to regulate their other senses ; thus there 

 are few plants or substances whose application to the 

 tongue produces an agreeable effect but are proper 

 for food. It must, however, be confessed, that the dis- 

 criminating quality in brutes, with regard to food, is greatly 

 assisted by their sense of smelling : the horse will not touch 

 water from a greasy bucket ; and his refusal takes place 

 before he has had time to ascertain the true cause. Nature 

 stimulates her creatures to take food by a double motive, 

 — the pleasure of taste and the pain of hunger. 



The soft palate, or velum palati {Plate W. f ; Plate VII. 

 Z), is nothing m^ore than an expanded uvula, which adheres 

 to both sides at the back of the mouth. The fixed point 

 whence it originates is the arch of the palate bone, which 

 terminates the hard palate. From this arch it inclines 

 backward till its free edge rests upon the epiglottis, one of 

 the parts of the larynx. Slanting in this direction it is 

 easily raised by any substance coming from the mouth ; but 

 is only the firmer closed by any thing attempting to egress 

 from an opposite direction. The air has not body sufficient 



