CHAP, v.] TASTE AND SMELL. 1033 



tions in this respect are met with ; many persons taste both 

 bitter and sweet things best at the back of the tongue ; and 

 some persons taste bitter things quite distinctly at the tip. 

 The salt taste is said to prevail at the tip and the acid taste at 

 the sides of the tongue ; but many persons experience acid and 

 salt tastes in those regions and those regions only in which they 

 experience bitter and sweet tastes. 



We have already said that bitter and sweet tastes seem to be 

 on a different footing from acid and salt tastes ; and we have a 

 certain amount of evidence that the two former sensations are 

 brought about by means of terminal organs different from those 

 by means of which the two latter are brought about. If some 

 of the leaves of a plant which grows in India and is called 

 G-ymnema sylvestre, be chewed, or if the mouth be washed with 

 a decoction of the leaves, for some little time afterwards bitter 

 and sweet tastes are lost, neither quinine nor sugar exciting the 

 usual sensations, though acid and salt tastes remain unaffected. 

 We may interpret this result as indicating that the drug in some 

 way or other 4 paralyzes,' that is to say, suspends the action of, 

 the terminal organs, whatever they may be, by means of which 

 bitter and sweet tastes are developed, but leaves untouched 

 those by which other gustatory sensations are developed. The 

 action of the same drug supports the further conclusion that 

 the terminal organs of bitter tastes are different from those of 

 sweet tastes; since by using an adequately weak dose of the 

 drug the sweet taste may be abolished while the bitter taste 

 remains distinct. 



Indeed it is probable that the distribution of the several 

 kinds of tastes over different regions of the mouth, which we 

 mentioned above, is dependent on the distribution of different 

 kinds of terminal organs; it is probable that we experience 

 bitter tastes by means of the back of the tongue because the 

 terminal organs of the bitter taste are limited to, or at least 

 most abundant in, the back of the tongue, those of the sweet 

 taste by the front of the tongue because the terminal organs 

 of the sweet taste are more abundant there ; and so on. If 

 a small quantity of a particular bromine derivative of the sub- 

 stance which from its remarkably sweet taste has been called 

 4 saccharine,' be placed carefully on the tip of the tongue, a 

 sweet taste is developed ; but if the same substance be carefully 

 placed on the back of the tongue the result is not a sweet but 

 a bitter taste. At least this is the result in the case of those 

 individuals who taste bitter at the back of, and sweet at the 

 tip of, the tongue. From this we may infer that, in such 

 tongues, the specific terminal organs of the sweet taste are 

 more or less completely limited to the front, and those of the 

 bitter taste to the back of the tongue, both sets of terminal 

 organs being of such a nature that while quinine affects the one 



