334 THE HUMAN BODY. 



vapors have this powerful influence upon the olfactory 

 organ, others, as pure air, do not stimulate it at all. 



Taste. The organ of taste is the mucous membrane on 

 the upper side of the tongue, and possibly on other parts of 

 the boundary of the mouth-cavity. The mucous membrane 

 of the tongue presents innumerable elevations or papillae 

 (Fig. 46) of three kinds (p. 139). The filiform papillae are 

 organs of touch, for the tongue has the sense of touch as 

 well as of taste. The circumvallate and fungiform papillae 

 contain the endings of branches of the glosso-pharyngeal 

 and trigeminal nerves (pp. 292, 293), which, when excited 

 by sapid bodies, stimulate the taste-centres in the brain. 



Many so-called tastes (flavors) are really smells; odorif- 

 erous particles of substances which are being eaten reach 

 the nose through the posterior nares and arouse smell sen- 

 sations which, since they accompany the presence of ob- 

 jects in the mouth, we take for tastes. Such is the case 

 with most spices; when the nasal chambers are blocked or 

 inflamed by a cold in the head, or closed by pinching the 

 nose, the so-called " taste" of spices is not perceived when 

 they are eaten; all that is felt when cinnamon, e.g., is 

 chewed under such circumstances is a certain pungency 

 due to its stimulation of nerves of common sensation in the 

 tongue. This fact is sometimes taken advantage of in the 

 practice of domestic medicine when a nauseous dose, as 

 rhubarb, is to be given to a child. 



What is the organ of taste? What is found on the mucous mem- 

 brane of the tongue? What papillae are concerned in the tactile sen- 

 sibility of the tongue ? In the gustatory ? What nerves supply the 

 taste-papillae? 



What are many so-called tastes? Illustrate. 



