85 O B S E R V A T I O N S ON THE
5. As the waile of the feveral organs is carried off by the veffels, either
circulating or abforbent, for we have riot yet heard of abforbent^ iierves,
though, indeed, hypothefes not lefs extravagant have, of late, been printed
on this fubjedl, why Ihould we doubt, that the ckculating fluids can
add a particle in the place of one that has been carried off, or that an arteiy
can fupply what has been abforbed by a lymphatic vein ? As it is
granted that the fecretion of all other kinds of matter in the bodies of animals
is performed by the branches of the arteries, is it not incredible, that
there ihould be an exception to the general rule in the fecretion. of the noulifhrnent
? Surely that power which can convert the. food into blood, and
can change the blood into bile and fcmen, is fufficient to convert it into
nourifliment.
6. I have endeavoured to ihow that the red colour produced by madder
in the bones, or in their callus, in a living animal, is owing to a fecretion
from the arteries.
I have further obferved, that callus and cicatrice are as readily produced
in the hind legs of a frog, after cutting, tranfverfely, its fpinal marrow or
fciatic nerve, as when the nei*ves ai'e entire. I will now add, that, in calli,
cicatrices, or accretions, there are numberlefs new-formed veffels filled, in
the living animal, with red blood, and which can readily be injeâed *. Nay,
I found, by the following experiment, proof of a fa£i: which it was difficult
to afcertain by the application of the microfcope, to wit, that fuch newformed
veffels, produced from the oppoiite fides of a wound, unite into
continued canals or anaftomofe. I made, firft, a longitudinal incifion
through the llcin, and mufcles, and peritoneum of the abdomen of a living
pig. I then fewed together accurately the fides of the wound, and, after
fome weeks, found that they were firmly reunited. I then killed the pig,
and made a longitudinal incifion into its abdomen, parallel with, and about
N E R V O U S S Y S T E M . 87
two inches diftant from the former incifion, and two tranfverfc incifions, interfering
the longitudinal incifions lower than the upper end, and higher
than the under end of the cicatrix. By this means 1 had furrounded an
oblong fquare portion of the containing parts of the abdomen by my incifions.
Yet when, after all, I threw an injeclion into the aorta, 1 found it
had filled a number of veffels in the oblong fquare portion *.
If then, in a callus, new earthy or offeous fibres, and new veffels, can be
formed by the original arteries, muft we not believe that the walle of this
earth, and of thofe veffels, can be ever after fupplied by the arteries which
formed them ? If fo, are we not to conclude that the wafte of other arteries,
and of other organs, is fupplied in the fame manner from the arte-^
ries ?
7. If the quantity of blood naturally circulating through a limb be diminiihed,
as by tying the trunk of the brachial artery in the operation for an
aneurifm, the arm lofes part of its ftrength and fize; but the lofs is lefs than,
at firil fight, might be expected, becaufe the anaftomofing canals foon come
to be greatly enlarged.
Upon the whole, I apprehend, there are few points in phyfiology fo
clear as,
1. That the arteries prepare and direitly fecrete the nourifliment in aU
our organs.
2. That the nerves do not contain nor condu£t the nourifliment, but,
by enabling the arteries to ad properly, contribute indiredly to nutrition.
C H A F-
• See Tab. XLVII.
I