Because the nerves of taste are most abundantly distributed to the under surface of the tongue; and when solid substances have been in the mouth a little while, they impregnate the saliva of the mouth with their particles _and come in contact in a fluid solution with the gustatory nerves_.
999. _Why if we put a nub of sugar to the tip of the tongue has it no taste?_
Because the gustatory nerves are _not distributed to that part of the tongue_.
[Verse: "Wine is a mocker, strong drink is raging; and whosoever is deceived thereby is not wise."--PROVERBS XX.]
1000. _Why, when we draw the tongue in, do we recognise the sweetness of the sugar?_
Because the dissolved particles of sugar are _brought in contact_ with the nerves of taste.
1001. _Through what nerves are we made sensible of the contact of sugar with the tip of the tongue?_
Through the nerves of _feeling_, which are abundantly distributed to the tongue to guide it in its controul over the mastication of food.
1002. _Why do connoisseurs of wines close their mouths and distend their chins for a few seconds, when tasting wines?_
Because they thereby bring the wine in contact with the under surface of the tongue, _in which the gustatory nerves chiefly reside_.
1003. _Why do they also pass the fumes of the wines through their nostrils?_
Because _flavour_, in its fullest sense, comprehends not only the _taste_, but the _odour_ of a substance; and, therefore, persons of experience attend to both requisites.
The various conditions of taste are defined to be:--
1. Where sensations of _touch_ are alone produced, as by glass, ice, pebbles, &c.
2. Where, in addition to being _felt_ upon the tongue, the substance excites sensation in the _olfactory nerves_, as by lead, tin, copper, &c.
3. Where, besides being _felt_, there are peculiar sensations of _taste_, expressive of the properties of bodies, as salt, sugar, tartaric acid, &c.
4. Where, besides being _felt_ and _tasted_, there is an _odour_ characteristic of the substance, and essential to the full development of its flavours, as in cloves, lemon-peel, caraway-seed, and aromatic substances generally.
Because there are distributed to various parts of the body fine nervous filaments, which have for their special duty the transmission to the brain of impressions made upon them _by contact_ with substances.