tomach.

5. The valve of the colon is well adapted to prevent the retrograde motion
of the excrements; yet, as this valve is possessed of a living power, in
the iliac passion, either from spasm, or other unnatural exertions, it
keeps itself open, and either suffers or promotes the retrograde movements
of the contents of the intestines below; as in ruminating animals the mouth
of the first stomach seems to be so constructed, as to facilitate or assist
the regurgitation of the food; the rings of the oesophagus afterwards
contracting themselves in inverted order. De Haeu, by means of a syringe,
forced so much water into the rectum intestinum of a dog, that he vomited
it in a full stream from his mouth; and in the iliac passion above
mentioned, excrements and clyster are often evacuated by the mouth. See
Section XXV. 15.

6. The puncta lacrymalia, with the lacrymal sack and nasal duct, compose a
complete gland, and much resemble the intestinal canal: the puncta
lacrymalia are absorbent mouths, that take up the tears from the eye, when
they have done their office there, and convey them into the nostrils; but
when the nasal duct is obstructed, and the lacrymal sack distended with its
fluid, on pressure with the finger the mouths of this gland (puncta
lacrymalia) will readily disgorge the fluid, they had previously absorbed,
back into the eye.

7. As the capillary vessels receive blood from the arteries, and separating
the mucus, or perspirable matter from it, convey the remainder back by the
veins; these capillary vessels are a set of glands, in every respect
similar to the secretory vessels of the liver, or other large congeries of
glands. The beginnings of these capillary vessels have frequent anastomoses
into each other, in which circumstance they are resembled by the lacteals;
and like the mouths or beginnings of other glands, they are a set of
absorbent vessels, which drink up the blood which is brought to them by the
arteries, as the chyle is drank up by the lacteals: for the circulation of
the blood through the capillaries is proved to be independent of arterial
impulse; since in the blush of shame, and in partial inflammations, their
action is increased, without any increase of the motion of the heart.

8. Yet not only the mouths, or beginnings of these anastomosing capillaries
are frequently seen by microscopes, to regurgitate some particles of blood,
during the struggles of the animal; but retrograde motion of the