t, which presides over the
insertion of the thoracic duct, into the subclavian vein; many have
believed this also to perform the office of a valve, both to admit the
chyle into the vein, and to preclude the blood from entering the duct; but
in my opinion it is scarcely sufficient for this purpose." Haller, Elem.
Phys. t. vii. p. 226.

2. The mouths of the lymphatics seem to admit water to pass through them
after death, the inverted way, easier than the natural one; since an
inverted bladder readily lets out the water with which it is filled; whence
it may be inferred, that there is no obstacle at the mouths of these
vessels to prevent the regurgitation of their contained fluids.

I was induced to repeat this experiment, and having accurately tied the
ureters and neck of a fresh ox's bladder, I made an opening at the fundus
of it; and then, having turned it inside outwards, filled it half full with
water, and was surprised to see it empty itself so hastily. I thought the
experiment more apposite to my purpose by suspending the bladder with its
neck downwards, as the lymphatics are chiefly spread upon this part of it,
as shewn by Dr. Watson, Philos. Trans. v. 59. p. 392.

3. In some diseases, as in the diabetes and scrophula, it is probable the
valves themselves are diseased, and are thence incapable of preventing the
return of the fluids they should support. Thus the valves of the aorta
itself have frequently been found schirrous, according to the dissections
of Mons. Lieutaud, and have given rise to an interrupted pulse, and
laborious palpitations, by suffering a return of part of the blood into the
heart. Nor are any parts of the body so liable to schirrosity as the
lymphatic glands and vessels, insomuch that their schirrosities have
acquired a distinct name, and been termed scrophula.

4. There are valves in other parts of the body, analogous to those of the
absorbent system, and which are liable, when diseased, to regurgitate their
contents: thus the upper and lower orifices of the stomach are closed by
valves, which, when too great quantities of warm water have been drank with
a design to promote vomiting, have sometimes resisted the utmost efforts of
the abdominal muscles, and diaphragm: yet, at other times, the upper valve,
or cardia, easily permits the evacuation of the contents of the stomach;
whilst the inferior valve, or pylorus, permits the bile, and other contents
of the duodenum, to regurgitate into the s