706 THE SENSE OF TASTE. 



of hearing, we know that sounds differ from one another 

 according to the differences in the number of undulations 

 producing them ; and in the case of vision, it is reasonably 

 inferred that different colours result from differences in 

 the number of undulations, or in the rate of transit, of the 

 principle of light. But, in the cases of taste and smell, no 

 such probable explanation has yet been offered. It would 

 appear, indeed, from the experiments of Horn, that while 

 some substances taste alike in all regions of the tongue's 

 surface, others excite different tastes, according as they are 

 applied to different papillae of the tongue. This observa- 

 tion, if confirmed, would seem to show that, in some cases 

 at least, different fibres are capable of receiving different 

 impressions from the same sapid substance. 



Much of the perfection of the sense of taste is often due 

 to the sapid substances being also odorous, and exciting 

 the simultaneous action of the sense of smell. This is 

 shown by the imperfection of the taste of such substances 

 when their action on the olfactory nerves is prevented by 

 closing the nostrils. Many fine wines lose much of their 

 apparent excellence if the nostrils are held close while they 

 are drunk. 



Very distinct sensations of taste are frequently left after 

 the substances which excited them have ceased to act on 

 the nerve ; and such sensations often endure for a long 

 time, and modify the taste of other substances applied to 

 the tongue afterwards. Thus, the taste of sweet substances 

 spoils the flavour of wine, the taste of cheese improves it. 

 There appears, therefore, to exist the same relation between 

 tastes as between colours, of which those that are opposed 

 or complementary render each other more vivid, though 

 no general principles governing this relation have been 

 discovered in the case of tastes. In the art of cookie g, 

 however, attention has at all times been paid to the con- 

 sonance or harmony of flavours in their combination or 

 order of succession, just as in painting and music the 



