Extensibility of texture exists in the absorbent system. 1st. The
thoracic duct is distended in an evident manner by injection, before
the rupture of its peculiar membrane takes place. 2d. I have said that
the absorbents examined around the serous membranes in a living animal,
principally in the liver, often exhibit little bladders or considerable
dilatations. Are these dilatations varices? is there an analogous
character in this respect, between the absorbents and the veins? I
know not; whatever they are, they can be very considerable in a long
absorbent vessel. 3d. When we tie the thoracic duct, not only that
swells, but the lymphatic vessels of the abdomen also dilate, and this
ligature is the most convenient means of observing the lacteals. This
extension has undoubtedly limits; carried too far, it would probably
produce in a natural state the rupture of the vessels, as happens
from injections. We have not yet any data founded upon observation
or experiment, respecting this rupture, though some authors have
endeavoured to explain by it the formation of most dropsies.
Contractility of texture is evident in the absorbent system. 1st. When
the thoracic duct is distended even in a recent dead body, and the
fluid is discharged by puncture, it immediately contracts. 2d. All the
absorbents contract also as soon as there is no more fluid in their
cavity. This phenomenon is remarkable during the absorption of chyle;
when that is finished, these vessels evidently disappear by the effect
of this contraction. 3d. The absorbent glands, swelled at the moment
chyle is passing through them, afterwards lose much of their size by
this contractile power.