Taste seems to have two chief uses:
1. It invites us by pleasure to repair the losses which result from the use of life.
2. It assists us to select from among the substances offered by nature, those which are alimentary.
In this choice taste is powerfully aided by the sense of smell, as we will see hereafter; as a general principle, it may be laid down that nutritious substances are repulsive neither to the taste nor to the smell.
It is difficult to say in exactly what the faculty of taste consists. It is more complicated than it appears.
The tongue certainly plays a prominent part in the mechanism of degustation—for, being endued with great muscular power, it enfolds, turns, presses and swallows food.
Also, by means of the more or less numerous pores which cover it, it becomes impregnated with the sapid and soluble portions of the bodies which it is placed in contact with. Yet all this does not suffice, for many adjacent parts unite in completing the sensation —viz: jaws, palate, and especially the nasal tube, to which physiologists have perhaps not paid attention enough.
The jaws furnish saliva, as necessary to mastication as to the formation of the digestible mass. They, like the palate, are gifted with a portion of the appreciative faculties; I do not know that, in certain cases, the nose does not participate, and if but for the odor which is felt in the back of the mouth, the sensation of taste would not be obtuse and imperfect.
Persons who have no tongue or who have lost it, yet preserve the sensation of taste. All the books mention the first case; the second was explained to me by an unfortunate man, whose tongue had been cut out by the Algerines for having, with several of his companions, formed a plot to escape from captivity.
I met this man at Amsterdam, where he was a kind of broker. He was a person of education, and by writing was perfectly able to make himself understood.