THE SENSES.

Dominion, Volume 1, Issue 282, 21 August 1908, Page 11

THE SENSES.

EVES TASTE,.BONES,HEAP; AND .HAIR ' FEELS.. : SOME CUIiiOUS FACTS. Recent experiment Jlas - demonstrated Boveral curious things about'the senses. . It has shown that we can taste witli'our eyes, hear with .our'mouths, feel with our tongues, and'even taste with our .uoses. . To prove that your nose does a large part of your tasting for you, hold. your nostrils closed, shut your; eyes tight, and get somebody to feed you in succession with a piece of apple, a piece of potato, and a piece of onion. You will; not.be able to tell which is which.v But tasting tfith your eyes certainly does seem an odd idea.. You may try it for yourself,- if you wish. Dissolve a little quinine in water, and put a drop in your eye. You will taste it'almost immediately—the reason being simply that the fluid, or some of it at all events, ~ finds ,it- way. down ..through the tear duct into tho back part of tho mouth. If you-will take the troublo to examine the lower lid of either of'your eyes in a mirror you will notice a little round" opening near the inner, corner. This is the upper end of a tube which extends downwards to the cavity beHiiid the mouth. The tube in question is called the tear duct, because its purpose is to carry offi the. surplus of water that is continually pouring into tho eyo, to keep the .organ of vision washed and clean. "When you cry there is more fluid than the pipe can dispose of, and so it overflows in what are called tears. TASTING WITH THE NOSE. It is -tho tear duct, then, that enables you, in a 'manner of speaking, to taste with your When it comes to tastine with youi nose, the experiment already mentioned, with .tljo .potato, onion, etc., affordß a, pretty good notion- of the important ' part played by the olfactory sense in the perception of flavours. Generally, speaking; it may he said that all that ; is.;inost taste,.such as-the ■appreciation ,of the "bouquet" of wino, depends; mainly upon the extraordinary tive nerve endings which' line the nasal passage. •'

When you sniff, to smell something,' you do so in/order to draw over theso nerve endings, a current- of air containing ..the odour. So sensitive, are thoy .that,'as has been proven by recent scientific experiments, they are able to detect a 2,000,000 th part of a milligramme of musk. This amount is just about tho next thing to nothing at all. Conceive, if you can, now infinitely tiny must be; tlie- ; particles of scent stuf? set iiiloat in tljO',air.vby a rose! Yet we aro able to perceive them,:

On the'other hand, a very strong smell will, actually paralyse the little nerves' of the...n6so, .rendering them for some time af? tortvards. unable to distinguish between mild fragrances that are agreeable. Furthermore, and most curious of all, even the most delicious scent, such- as that of the rose, becomes disagreeable 'if highly 'concentrated. Tho finest essence of violets, which comes to market, in jars in the form of a dry powder, -. is extremely offensive to tho nostrils, requiring great dilution in order to render it pleasant.' What wo know.as "flavour," where tilings to eat are concerned, is a combination, as it were, of taste and smell. Undoubtedly the olfactory sense is the more important of tho two, whore the pleasures of tho table are concerned, and through it .we . are able to appreciate choice viands and the cooking which renders ,them palatable. RECENT DISCOVERIES. '' There are a good many other things relating tA' taste, however, which, as shown bv recent discoveries of science, are curious. Thus, for example, you taste bitter things with one part of your tongue „ and sweet things with another. This is because different sets of nerves, located in one placoand another on tho surface of that useful member, respond to different kinds of impressions. Tako a little sugar, to begin with, and apply it in small quantities, in succession, to,'different parts of your own tongue. ' You will And tliat it sweetest—in other words,-its sweetness is perceived most acutely—at the end of the tongue. But; if . you try' the same thing with powdered qiiininoj you will'discover that the tip of the tonguo hardly notices it. In order to taste it much, you iriust put the quinine on fcho back paft of the tonguo.

' This is tho reason why, when you have taken quinino, into your mouth, you. hasten, to swallow it as quickly as possible. If permitted to lodge only for a moment on tlio back of tlio, tongue, it'produces a very strong and disagreeablo taste impression. These little experiments with sugar and quinino'' provo that the end of youiv tongue is most sensitive to sweet, and tho back portion most sonsitivQ to bitter. Next, take . a small quantity ,of lemon juico,' and try it. You . will, find that its sourness is perceived most acutely not. by the tip, nor by. the rear part, but by tho edges of tho tongue. Tho edges, in fact, aro moro sensitive to any kind of acid than other portions of tho organ. Leaving tho olfactory senso out of consideration, what wo call taste resides chiefly in the tongue, though the "taste buds," as they are called, iiro also scattered over tho surfaco of tho soft palate, tho tonsils', and the upper pharynx —which last is tho great cavity behind tho nose. Tho tasto buds (easily discernible under a moderate power of tho'microscope) arc so named because ot their' shape, and each 0110 of them marks the point of emergenco of a tiny nervo. In other words, they contain the gustatory nerve endings, and are most numerous at tho baso of tho tongue. CAUSE OF PARTIAL DEAFNESS'.. Now—and. hero is a .very curious fact—if you were to put a bit of quinine powder on your tongue, and it did not melt, you would not tasto it at all. A dry substance of any kind has no taste; in order to affect the gustatory nerve endings, it must pass into solution. On the other hand, if the tongue is dried, it is rendered for the timo being incapable of tasting anything. All the senses aro inter-related. 'Thus, for example, partial deafness may be 'due to an obstruction of tha nose. We have already referred to using the tongue as an organ of feeling. Tho tongue is in this respect tho most sensitive part of the body—more sensitive even than the tips of the fingers. By its means you determine with utmost accuracy tho size of morsels of food before you swallow them. If 'you will take an ordinary pair of dividers, such as draughtsmen use, and apply tho instrument to your arm, .you will find that the sharp points are not distinguishable as.. two in number unless they arc quite ,a little distance apart. But if you will place them in contact with the end of your'tongue you will be able to bring the. points very close together and .yet perceive that thero are two of them. This shows how exceedingly, sensitive and delicate is the tonguo as an organ of touch. XVhen you eat, your tonguo is continually wandering about in your mouth for tho purposo .of feeling.. Until it tolls you that tho' morsels aro small eniugh you do not swallow a bito of moat which you have been chewing. Its decision in the matter is unernng-T-as much 1 so' as if tho bits of food were under examination' by the eye. This, of course, is of • obvious importance to the digestion, anil incidentally avoids danger of choking. And at the conclusion, of a meal, ,if any morsels remain between the teeth;, the tonguo is almost certain to find them and give warning—a notification 'most useful for.,the preservation of. tho teeth themselves. HEAKING WITH ONE'S;-MOUTH. The fact that it is easily possible to hear with ono's m.outh is shown by a contrivance frequently used by deaf pecple nowadays. It is simply a fan of vulcanite, of tio same shape as a palm leaf fan, tho upper edge of which is held by tho doaf person between his teeth. Thus held, it serves as a sort of auditory diaphragm, receiving sounds and transmitting them through tho teeth to tho nerves of hearing. r •; • Everybody who has over been to tho dentist's knows only' too well • that the teeth have .nerves connected with them. : ' These horves lead. to. certain knots of 'nervo- tisSuo called ganglia, from which also proceed other nerves that pass to the'auditory 1 chamber of the ear, thanks to which indirect connection sound vibrations ■ communicated through the teeth are. conveyedji.to, itPPy rjiieKTiei. and are. thus perceived by what wo' call the sense of hearing! alf%bu ll grind;r r together over so slightly, you will find that you hear tho sound very distinctly. Ib is morely another illustration_of-tho same-idea.

Various troubles may be causes of deafness, but so long as the piano in tho auditory chamber is; in running order, one can hear with one's mouth, by tho help of afan of. the kind hero spoken of. That is to say, one can hear if one has.toeth'to hear with. If you have no teeth the bones of the jaw, and even. of' the chest, will carry sound for you. Just touch one of tho lino hairs on the back of your hand or wrist and you will find the sensation of . touch is fully as acute as in tho skin itself.