sensations, their constant recurrency, and the contiguity of the coats. And there is a perfect agreement of the final cause with the efficient here, as in other cases. For any great degree of voluntary power over the muscular coat of the bowels would much disturb the digestion of the aliment, as those nervous persons experience, who are so unhappy as to be exceptions to the general rule, through the influence of associated circumstances.
Section III
THE SENSE OF SMELL.
Smell may be distinguished into two sorts: first, that exquisite sensation, which odoriferous bodies impress upon the nose by means of alternate inspiration. This is smell, in the peculiar and most proper sense of the word; and it resides chiefly, or perhaps entirely, in that part of the pituitary membrane, which invests the cells of the ossa spongiosa. Secondly, that sensation or flavour, which most kinds of aliment and medicines impress upon the whole pituitary membrane during mastication, and just after deglutition. And this last makes a principal part of the pleasures and pains which are usually referred to the taste. For when a person has a cold, i.e. when the pituitary membrane is obstructed and loaded with mucus, meats lose their agreeable flavours; and the same thing happens in a polypus narium.
Besides this, it is to be observed, that the pituitary membrane has an exquisite sensibility, which may be referred to the head of feeling. For active powders, i.e. sternutatories, seem to irritate the membrane of the nose in the same way, as they do a part of the skin deprived of the cuticle, only in a greater degree, and more immediately. And thus smells themselves may be referred to the head of feeling; since strong smells are often observed to occasion sneezing.
It may also be remarked, that as the organ of feeling passes insensibly into that of taste, so the organ of taste does into that of smell. And these three senses have a much greater resemblance to one another, than any of them has to the sight, or to the hearing; or than the sight and hearing have to each other. However, the organ of feeling is distinguished from that of taste by its being covered with the hard cuticle, and the organ of taste
