SENSES OP SMELL AND TASTE. 



5Y7 



is taste-sensation confined entirely to tlie tongue. It can be 

 shown that the back edges and tip of the tongue, the soft palate, 

 the anterior pillais of the fauces, and a limited portion of the 

 back part of the hard palate, are conceited in tasting. Making 

 allowances for individual differences, it may be said that the 

 back of the tongue appreciates best bitter substances, the tip,' 

 sweet ones, and the edges acids. 



If any substance with a decided taste be placed upon the 

 tongue when wiped quite dry, it can not be tasted at all, show- 

 ing that solution is essential. 



If a piece of apple, another of potato, and a third of onion, 

 be placed upon the tongue of a person blindfolded, and with 

 the nostrils closed, he will not be able to distinguish them, 

 showing that the senses of smell and of taste are related ; or, 

 perhaps, it may be said that much that we call tasting is in 

 large part smelling. When the electrodes from a battery are 

 placed on the tongue, a sensation of taste is aroused, described 

 differently by different persons; also when the tongue is quick- 

 ly tapped, showing that, though taste is usually the result of 

 chemical stimulation, it may be excited by such as are electrical 

 or mechanical. 



But it is not to be forgotten that we have usually no pure 

 gustatory sensations, but that these are necessarily blended 



Fig. 421. 



Fig. 422. 



Fig. 421.— Medium-sized circomvallate papilla (after Sappey). 



FiQ. 482.— Various kinds of papillae (after Sappey). 1, ftingiforai: 2, 3, 4, 5, 6, filiform: 

 7, liemispherical papillae. ' -= . 



with those of common sensation, temperature, etc., and that our 

 judgments must, in the nature of the case, be based upon highly 

 87 



