Taste
one of the special senses. The parts of the mouth affected by sapid sub- TASTE stances are the surface and sides of the tongue, the roof of the mouth, and the entrance to the pharynx. The mucous membrane is invested by stratified squamous epithelium, which, over the surface of the tongue, covers little vascular prolittle sharp or rounded projections; the the papillæ of the sides and upper part of the tongue with the naked eye, as little sharp or rounded projections; the latter, thickly clustered at the tip and sides, may appear, if the system is out of order, as little red points like those of a strawberry. In the cat tribe the papillæ are hard and curved backward into the mouth, so that the animal can use the tongue as a scraper to remove the flesh from the bones of its prey. The pointed papillæ are termed "filiform."
They are essentially the same in structure, differing alone in shape and size. At the back of the tongue are some 8 or 10 papillæ of quite a different nature, called "circumvallate." ranged to form a V with its angle pointing backward. These are hardly papillæ at all, but may be looked on rather as tiny patches of trenched out from the surrounding parts.
They are armucous membrane Into these trenches Ebner's glands secrete a watery albuminous fluid, keeping them perpetually moist and free from foreign particles. In the epithelium lining these trenches curious little bodies called taste bulbs are lodged; and, as these are the parts which are probably more especially concerned in taste, they must be carefully described. Each taste lining these trenches curious little bodbox, the walls of which are composed of flat elongated epithelial cells fitted side by side like the staves of a cask.
The taste bulbs open each by a little pore into the trer trench, and into the deeper box, the walls of which are composed of flat elongated epithelial cells fitted side by side like the staves of a cask. The taste bulbs open each by a little ably for the protection of the sensory cells which it contains. These cells are much elongated, and end each in a tiny bristle which projects with those of their companion cells from the little pore into the trench, and is here moistened by the juice of Ebner's gland and whatever sapid substance may be present. The impressions which these sensory cells receive from the bristles, say by the action of a bitter like "hops," is carried by the delicate nerve which starts from the opposite end of the cell out of the taste bulb directly to the brain. Within each taste bulb are other cells, which separate and support the sensitive cells, and are similar to analogous structures seen in the sensory epithelium of the eye, and nose, and ear.
While it is almost certain that these taste bulbs are organs of taste, it is not TASTE ole of dissolving in the equally certain that other parts are not involved. It may be remarked that substances capable juices of the mouth are alone tasted.
Marble, wood, flint, are devoid of taste, and so is pure starch; these are all of them quite insoluble in water. By the aid of various means we can convert the These examples will last-named substance into a very soluble "dextrine," yet this is tasteless. Another chemical product of the starch is a soluble substance termed "dextrose," which has a sweet taste and is commonly termed "grape sugar." equally produced on stimulating the whole of the gustatory area, and indeed each taste seems to have some special are capable of giving rise to this sensation.
Stare The various taste sensations are not equally produced on stimulating the bitter principles passes to the back of whole of the gustatory area, and indeed each taste seems to have some special If we take a piece of quassia or a hop the juice of the mouth laden with these the mouth that the taste is felt at all. Our knowledge of what really takes the juice of the mouth laden with these the mouth that the taste is felt at all. conscious of taste, and it is only when bitter principles passes to the back of Our knowledge of what really takes place when an external agency affects the senses, sets up a nerve motion which travels to the brain and there induces a sensation, is very limited. an English scientist to see if this law Mendeléef discovered what is termed the Periodic Law in chemistry, it occurred to holds good for taste and smell; this was found to be the case (see "Proceedings" of the Royal Society of Edinburgh, 1885- 1886; and "Brain," 1886). Newlands found that if we arrange the elements in a series, beginning with that one which has the lowest and passing to that which has the highest atomic weight, a periodic recurrence of function or property is found. Lang There is a general resemblance in physical properties between the 1st, 8th, 15th, etc., and between the 2d, 9th, 16th, etc. Those elements picked out of the series from their resemblance and periodic recurrence Mendeléef arranged in groups (see ATOMIC THEORY), and found that similar compounds of these elements have similar tastes. To take an example (group 1), the chlorides of lithium, sothat similar compounds of these elements all salt, while the sulphates of these elements are all saline bitters. It is evident that this group of elements, similar in their physical properties, can also proments are all saline bitters. It is evident that this group of elements, similar in their physical properties, can also protaste a physiological effect with some common physical quality.
TASTE Like smell, the sense of taste is placed at the entrance of the alimentary canal, and affords us knowledge of the nature of the food about to be eaten. We have so far adapted ourselves to our environments that, as a rule, those substances which please these senses are salutary foods, and the converse is equally true.
This is however, a rule with many exceptions.