THE ORGANS OF SPECIAL SENSE. 61 



The Sense of Taste. The sense of taste lies chiefly in 

 the taste buds as they are called which are filled with 

 gustatory cells and are found in the papillae of the tongue, 

 principally in the circumvallate papillce at the back of the 

 tongue, which are few in number and arranged in a V- 

 shape. There is also a certain power of taste in the tip 

 and sides of the tongue but little in the upper surface or 

 dorsum. Only five special tastes can be distinguished: 

 bitter, sweet, acid, sour, and salt, but sometimes more 

 than one can be distinguished at a time, as bitter and 

 sweet. Every one can distinguish between different 

 tastes but the power varies in different people and 

 with different conditions. Certain tastes seem to be 

 better distinguished in certain places, as sweet at the 

 tip and bitter at the back of the tongue. Moreover, 

 the sense of taste is very dependent upon the sense 

 of smell, especially in the case of aromatic and savory 

 substances, which one really does not taste but smell. 

 If one held his nose and closed his eyes he would not 

 know from the taste whether he was eating onion or 

 apple. This leads to the habit of pinching the nose 

 when taking nauseous medicines. 



To be tasted a substance must be in solution. Friction 

 against the tongue, lips or cheek increase the sense of 

 taste. A temperature of 100 Fahrenheit favors taste, 

 while both great heat and great cold impair it. 



There are probably at least two nerves of taste, the 

 lingual branch of the trifacial or fifth cranial and the 

 gustatory branch of the glosso-pharyngeal. 



Along with the sense of taste there are other senses in 

 the mouth which play an important part, such as 

 pressure and the sense of heat and cold, and it is often hard 

 to distinguish them from the pure sensation of taste, 

 which indeed is always accompanied by them. 



Salivary Glands. On either side of the mouth are 

 three racemose glands for the secretion of the saliva, 

 which serves to soften and lubricate the food and parti- 

 ally to digest starches by means of its ferment, ptyalin. 



