General Anatomy, Applied to Physiology and Medicine, Vol. 2 (of 3)Bichat, Xavier
Science
General Anatomy, Applied to Physiology and Medicine, Vol. 2 (of 3)
Bichat, Xavier
Human anatomy; Human physiology
Many distinguished anatomists have thought that the veins absorb,
and in relation, to their use, they have joined these vessels to the
lymphatics. Haller, Meckel, and before them, Kaw Boerhaave, were of
this opinion. Such names deserve undoubtedly an examination of the
reasons advanced; let us now consider these reasons. 1st. The thoracic
duct has been seen obliterated, and absorption continuing to go on,
while life was preserved in the animal. But as they have not observed
whether the great right lymphatic and its accessories were obliterated,
nothing can be concluded from this fact. Besides the observations upon
this point do not appear to me to be well ascertained. They could
decide this question very easily, I think, by tying during digestion,
the thoracic duct at its entrance into the jugular; it could be
readily come at on the inferior part of the neck, where it could be
distinguished by its whiteness; no important part need be wounded.
This experiment would throw great light upon the general question of
absorptions. 2d. Fine injections, made through the mesenteric vein,
cover the peritoneum; hence it has been concluded that the absorbents
terminate in this vein. But as the venous extremities communicate
with the capillary system, and as this gives rise to the exhalants,
injections, by going through its numerous anastomoses, can easily be
spread in this way, which vitality shuts during life, but which the
flaccidity of the parts and the absence of sensibility open after
death. 3d. Compression of the superficial veins produces swelling of
the limbs; but as this compression is made at the same time upon the
absorbents, no inference respecting venous absorption can be drawn from
it. 4th. Kaw Boerhaave having introduced water into the intestinal
canal, it was afterwards found in the mesenteric veins; but this
experiment has been many times repeated since without giving the same
result. 5th. Add to these considerations the numerous experiments of
Dr. Hunter, to prove that venous absorption does not take place on the
surface of the intestines, and you will see that this absorption will
appear very uncertain, in these first respects.
But if you look at the question in other respects, you will be unable
to deny that certain facts present probabilities in favour of this
absorption. 1st. It is almost certain, that the venous extremities
take up by the way of absorption, the blood effused in the corpus
cavernosum. 2d. We do not see absorbents in the placenta, and yet the
umbilical vein takes up all the fluids of this body. 3d. Meckel having
injected a lymphatic vessel that went to a gland, the injected mercury
passed into a neighbouring vein.
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