und us, when applied to our palates, excite into action
the muscles of deglutition; and the material is swallowed into the stomach.
Here the new aliment becomes mixed with certain animal fluids, and
undergoes a chemical process, termed digestion; which however chemistry has
not yet learnt to imitate out of the bodies of living animals or
vegetables. This process seems very similar to the saccharine process in
the lobes of farinaceous seeds, as of barley, when it begins to germinate;
except that, along with the sugar, oil and mucilage are also produced;
which form the chyle of animals, which is very similar to their milk.

The reason, I imagine, why this chyle-making, or saccharine process, has
not yet been imitated by chemical operations, is owing to the materials
being in such a situation in respect to warmth, moisture, and motion; that
they will immediately change into the vinous or acetous fermentation;
except the new sugar be absorbed by the numerous lacteal or lymphatic
vessels, as soon as it is produced; which is not easy to imitate in the
laboratory.

These lacteal vessels have mouths, which are irritated into action by the
stimulus of the fluid, which surrounds them; and by animal selection, or
appetency, they absorb such part of the fluid as is agreeable to their
palate; those parts, for instance, which are already converted into chyle,
before they have time to undergo another change by a vinous or acetous
fermentation. This animal absorption of fluid is almost visible to the
naked eye in the action of the puncta lacrymalia; which imbibe the tears
from the eye, and discharge them again into the nostrils.

III. The arteries constitute another reservoir of a changeful fluid; from
which, after its recent oxygenation in the lungs, a further animal
selection of various fluids is absorbed by the numerous glands; these
select their respective fluids from the blood, which is perpetually
undergoing a chemical change; but the selection by these glands, like that
of the lacteals, which open their mouths into the digesting aliment in the
stomach, is from animal appetency, not from chemical affinity; secretion
cannot therefore be imitated in the laboratory, as it consists in a
selection of part of a fluid during the chemical change of that fluid.

The mouths of the lacteals, and lymphatics, and the ultimate terminations
of the glands, are finer than can easily be conceived; yet it is probable,
that the pores, or interstic