ugular vein; except
indeed that those collected from the right side of the head and neck, and
from the right arm, are carried into the right subclavian vein: and
sometimes even the lymphatics from the right side of the lungs are inserted
into the right subclavian vein; whilst those of the left side of the head
open but just into the summit of the thoracic duct.

5. In the absorbent system there are many anastomoses of the vessels, which
seem of great consequence to the preservation of health. These anastomoses
are discovered by dissection to be very frequent between the intestinal and
urinary lymphatics, as mentioned by Mr. Hewson, (Phil. Trans. v. 58.)

6. Nor do all the intestinal absorbents seem to terminate in the thoracic
duct, as appears from some curious experiments of D. Munro, who gave madder
to some animals, having previously put a ligature on the thoracic duct, and
found their bones, and the serum of their blood, coloured red.

II. _The Valves of the Absorbent System may suffer their Fluids to
regurgitate in some Diseases._

1. The many valves, which occur in the progress of the lymphatic and
lacteal vessels, would seem insuperable obstacles to the regurgitation of
their contents. But as these valves are placed in vessels, which are indued
with life, and are themselves indued with life also; and are very irritable
into those natural motions, which absorb, or propel the fluids they
contain; it is possible, in some diseases, where these valves or vessels
are stimulated into unnatural exertions, or are become paralytic, that
during the diastole of the part of the vessel to which the valve is
attached, the valve may not so completely close, as to prevent the relapse
of the lymph or chyle. This is rendered more probable, by the experiments
of injecting mercury, or water, or suet, or by blowing air down these
vessels: all which pass the valves very easily, contrary to the natural
course of their fluids, when the vessels are thus a little forcibly
dilated, as mentioned by Dr. Haller, Elem. Physiol. t. iii. s. 4.

"The valves of the thoracic duct are few, some assert they are not more
than twelve, and that they do not very accurately perform their office, as
they do not close the whole area of the duct, and thence may permit chyle
to repass them downwards. In living animals, however, though not always,
yet more frequently than in the dead, they prevent the chyle from
returning. The principal of these valves is tha