590 THE HUMAN BODY. 



tongue, since the sense of taste exists where no taste-buds can 

 be found. The filiform papillae are probably tactile. 



That substances 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 contributing much to the pleasures of 

 life, they are intellectually, like smells, of small value; the 

 perceptions we attain through them as to qualities 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 olfac- 

 tory 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 cir- 

 cumstances is a certain pungency due to its stimulating 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. Tactile 

 sensations play also a part in many so-called tastes. 



As the tongue, in addition to taste functions, possesses 

 lactile, temperature, and general sensibility, its nerve ap- 

 paratus must be complex; and there is even reason to be- 

 lieve that different nerve-fibres with presumably different end 

 organs are concerned in the different 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. Chemical com- 

 pounds are known which in such persons cause a pure sweet 

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

 tion if placed in the region of the circumvallate papillse; 

 these facts seem to show that the fibres concerned in bitter 

 and sweet sensation are distinct. Again, if leaves of a certain 

 plant (Gymnema sylvestre) be chewed, the capacity to taste 

 sweet or bitter things is lost for some time, but salts and acids 



