Food within that Cavity, and not only so, but press it in between the Dentes Molares on one side, as the Tongue does on the other, until they have sufficiently broken and divided it.
At the same time, whilst the Dentes Molares are breaking the Food, there flows into the Mouth a Salival Juice, which mixes with it, and not only serves to moisten it, and to render it more apt and easie to be divided, but seems to be the Ferment, by the Benefit of which the Food is dissolved and digested. And therefore it is intimately mixed with it, by the Teeth agitating or stirring them together in Mastication.
This Liquor, which we commonly call the Saliva, or Spittle, seems to be a Composition made of two several Juices, very different in their Nature: And therefore the several Parts of it are separated by their proper Glands, and Nature has planted no fewer than four Pair about the Mouth, which supply the Juices that make the Saliva; to wit, the Parotides, and the Glandulæ Nuckianæ, the
Glandulæ Maxillares internæ, and Sublinguales. Whereas if the Saliva were but one more simple Liquor, a less number of Glands might have been sufficient. At least there appears no Reason why one of every Pair should disembogue itself into the Mouth so very near to the Orifice, by which a Gland of some other Pair throws in its Juice; and they are not rather all planted at more equal distances from one another, so to flow in upon every part of the Aliment at the same time.
Not that I suppose, as there are four Pair of salivatory Glands, so there are four sorts of Juices supply'd from them, to make the Saliva; but, as I hinted before, that there are only two different Juices that constitute it. And these are not only sufficient, but more proper to excite and secure that Fermentation, which is necessary to Concoction. For we find that