up, the acuteness of their smell is far inferior to that of quadrupeds.
If it be said, that this action is not automatic in brutes, but an instinct, which they bring into the world with them; I answer, that the nearness of the muscles affected, viz. those which dilate the nose, larynx, and lungs, to the seat of the impression, makes it probable, that the motion depends upon the sensation, as in other instances mentioned in these papers, some of which are allowed by all.
It may be, that something of the same kind takes place in young children, as soon as their smell begins to be sufficiently acute. But it is so mixed with, and modelled by, voluntary motions, as to be separately indiscernible.
The second motion, or the contraction of the fauces, and upper part of the œsophagus, from the grateful flavours which ascend up into the nostrils behind the uvula, is part of the action of deglutition; but it could not properly be mentioned in the last Section, because it arises from a sensation referred to this.
Ungrateful flavours have often a contrary effect, and extend their influence so far as to preclude the passage through the gullet, and even throw back the ungrateful liquid or morsel with violence. And we may observe, that in many other cases also, when the pleasure passes into pain, the automatic motion thereon depending passes into one of an opposite nature; just as in algebra, when an affirmative quantity in the data is changed into a negative one, a like change is to be made sometimes, and yet not always, in the conclusion.
It deserves notice here, that pinching the nose prevents the perception of these flavours, as it seems, by checking the vibrations, which would run along the pituitary membrane. When the flavours are very pungent, they fix in the tip of the nose; or, if this be hindered by pinching the nose, they fly to the uvula, which is the nearest extreme part to this.
In like manner, pinching the nose, or pressing the lachrymal bag, whose membrane is continuous to the pituitary one, checks the sensation that gives rise to sneezing. And when looking at a strong light excites this action, or acrid vapours make the eyes water, we may conjecture, that vibrations pass through the lachrymal duct from the eye to the nose in the first case, and from the nose to the eye in the last. The watering of the eyes from drinking hastily, especially pungent liquors, from plucking a hair out of the nostrils, and from sternutatories, admit of a like explication.
And these instances may help to explain the sensations in the fauces, uvula, and tip of the nose, also the flowing of tears from the eyes, which attend grief. I conjecture that the stomach is particularly affected in grief; and that it sends up vibrations along the common membrane, to the fauces, uvula, tip of the
