unite the terminations of the arteries and veins; and separate both the
mucus, which lubricates the cellular membrane, and the perspirable matter,
which preserves the skin moist and flexible. And thirdly, the whole
absorbent system, consisting of the lacteals, which open their mouths into
the stomach and intestines, and of the lymphatics, which open their mouths
on the external surface of the body, and on the internal linings of all the
cells of the cellular membrane, and other cavities of the body.

These lacteal and lymphatic vessels are furnished with numerous valves to
prevent the return of the fluids, which they absorb, and terminate in
glands, called lymphatic glands, and may hence be considered as long necks
or mouths belonging to these glands. To these they convey the chyle and
mucus, with a part of the perspirable matter, and atmospheric moisture; all
which, after having passed through these glands, and having suffered some
change in them, are carried forward into the blood, and supply perpetual
nourishment to the system, or replace its hourly waste.

8. The stomach and intestinal canal have a constant vermicular motion,
which carries forwards their contents, after the lacteals have drank up the
chyle from them; and which is excited into action by the stimulus of the
aliment we swallow, but which becomes occasionally inverted or retrograde,
as in vomiting, and in the iliac passion.

II. 1. The word _sensorium_ in the following pages is designed to express
not only the medullary part of the brain, spinal marrow, nerves, organs of
sense, and of the muscles; but also at the same time that living principle,
or spirit of animation, which resides throughout the body, without being
cognizable to our senses, except by its effects. The changes which
occasionally take place in the sensorium, as during the exertions of
volition, or the sensations of pleasure or pain, are termed _sensorial