It is performed by means of a subtile spreading of nerves, peculiarly delicate; which continues through the membrane of the nose, the roof of the mouth, gullet, and the very stomach.
Taste is the next sensation, which nature has given us, not only as a distinguisher of proper food, but a sensation from which we receive many luxurious pleasures; and to the indulgence of this sensation, most evils and plagues to mankind, take their origin.
The tongue is the principal instrument of that peculiar quality; but if we examine somewhat closer into this affair, we shall find that the soul of pleasure and pain of that sensation, as well as that of smelling, has its seat in the stomach; for that which will taste pleasing and good at the first approach, will soon lose its relish when the stomach is gratified: and, if any thing tastes disagreeable, the stomach receives it with reluctance, and will ever incline to discharge it again.
The tongue is an instrument (if I may be allowed the term) very curiously constructed; it is moved by a variety of muscles, and serves not only for tasting, but also as a labourer, to shovel and to turn our meat between our grinders; so that nothing may escape being well masticated, and intermixed with that fine digesting balsam, the spittle, in order that it may be easily swallowed.
Besides this, it makes the most requisite instrument for the noble and excellent faculty of speaking; which forms one of the principal characteristics that distinguishes man from the brute creation.
The gullet or oesophagus, is the canal which conveys drink and food from the mouth to the stomach; this canal is a muscular, tendinous, and vascular tunic.
The commencement of it is in the mouth, and is called the pharynx; a curious structure, that receives the food, and by its contractive motion, and the help of the tongue, forces the aliment into the stomach.
The stomach is much like the bag of a Scotch bag-pipe; it lies immediately under the diaphragm or midriff, covered partly on the right side with the liver, and on the left side with the spleen. The left and superior part, is continued with the oesophagus; and the right and inferior part, or orifice, commences the intestines.
The first orifice is called the mouth of the stomach; and the second the pylorus, or porter: At the porter there is a curious valve which lets the aliment out by small parcels into the intestines, where it undergoes its various other changes.
The stomach has three teguments, a muscular, a tendinous, and nervous coat; this nervous coat has another slimy one, but this in reality, is a delicate lining, interwoven with nerves, and the ramifications of fine blood vessels.