THE EAR, HEARING, TASTE AND SMELL 205 



sisting of single taste-cells are widely spread over the tongue, 

 since the sense of taste exists where no taste-buds can be found. 

 The filiform papillae are probably tactile. 



In order for substances to be tasted they must be in solution: 

 wipe the tongue dry and put a crystal of sugar on it; no taste will 

 be felt until exuding moisture has dissolved some of the crystal. 

 Excluding the feelings aroused by acid substances, tastes proper 

 may be divided into sweet, bitter, acid, and saline. Although con- 

 tributing much to the pleasures of life, they are intellectually of 

 small value ; the perceptions we attain through them as to quali- 

 ties of external objects being of little use, except as aiding in the 

 selection of food, and for that purpose they are not safe guides at 

 all times. 



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

 particles of substances which are being eaten reach the olfactory 

 region through the posterior nares and arouse sensations which, 

 since they accompany the presence of objects in the mouth, we 

 take for tastes. Such is the case, e. g., with most spices; when the 

 nasal chambers are blocked or inflamed by a cold in the head, or 

 closed by compressing 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 stimulating nerves of touch 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. 



As the tongue, in addition to taste functions, possesses tactile 

 and temperature sensibility, its nerve apparatus must be complex; 

 and there is even reason to believe that different nerve-fibers 

 with presumably different end organs are concerned in the differ- 

 ent true tastes. Most persons taste bitter things better with the 

 back part of the tongue and sweet things with the tip, and in 

 some persons the separation of function is quite complete. Chem- 

 ical compounds are known which in such persons cause a pure 

 sweet sensation if placed on the tongue tip and a pure bitter sen- 

 sation if placed in the region of the circumvallate papillae; these 

 facts seem to show that the fibers concerned in bitter and sweet 

 sensation are distinct. Again, if leaves of a certain plant (Gym- 

 nema sylvestre) be chewed, the capacity to taste sweet or bitter 



