SMELL AND TASTE 203 



of the sensation reaching the insect's consciousness, if indeed 

 it is conscious in our meaning of the word, remains unknown 

 to us. 



The sense of taste very closely resembles that of smell, for 

 it is the perception of things through their chemical nature 

 — not of things at a distance but of things in contact with 

 the inside of our mouths. The distinction is clear in land 

 animals because for them smell is airborne whereas taste de- 

 pends upon contact. In animals that live in water the dif- 

 ference is less, and the two tend to merge into one — taste 

 ranging from a distance to actual contact. 



In land animals taste is confined to the mouth and is 

 mainly concentrated upon the tongue, where the cells reac- 

 tive to dissolved substances are clustered into small organs 

 known as taste-bulbs. The structure of the taste-bulbs might 



SURFACE OF T0N»5U£ 



TASTE 

 BULBS 

 on Sides 

 of 

 depression 



Fig. 14. A highly magnified section through part of the tongue showing taste 

 bulbs arranged at the sides of slight depressions of the surface. 



Fig. 15. A single taste bulb more highly magnified showing the thread-like 

 ends of the receptor cells projecting from the surrounding cluster. 



