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History of Animals   

arm; and it is in consequence of this local connexion that, when the
surgeon opens this vein in the forearm, the patient is relieved of
certain pains in the liver; and from the left-hand side of it there
extends a short but thick vein to the spleen and the little veins
branching off it disappear in that organ. Another part branches off
from the left-hand side of the great vein, and ascends, by a course
similar to the course recently described, into the left arm; only that
the ascending vein in the one case is the vein that traverses the
liver, while in this case it is distinct from the vein that runs
into the spleen. Again, other veins branch off from the big vein;
one to the omentum, and another to the pancreas, from which vein run a
number of veins through the mesentery. All these veins coalesce in a
single large vein, along the entire gut and stomach to the oesophagus;
about these parts there is a great ramification of branch veins.
As far as the kidneys, each of the two remaining undivided, the
aorta and the big vein extend; and here they get more closely attached
to the backbone, and branch off, each of the two, into a A shape,
and the big vein gets to the rear of the aorta. But the chief
attachment of the aorta to the backbone takes place in the region of
the heart; and the attachment is effected by means of minute and
sinewy vessels. The aorta, just as it draws off from the heart, is a
tube of considerable volume, but, as it advances in its course, it
gets narrower and more sinewy. And from the aorta there extend veins
to the mesentery just like the veins that extend thither from the
big vein, only that the branches in the case of the aorta are
considerably less in magnitude; they are, indeed, narrow and
fibrillar, and they end in delicate hollow fibre-like veinlets.
There is no vessel that runs from the aorta into the liver or
the spleen.
From each of the two great blood-vessels there extend branches
to each of the two flanks, and both branches fasten on to the bone.
Vessels also extend to the kidneys from the big vein and the aorta;
only that they do not open into the cavity of the organ, but their
ramifications penetrate into its substance. From the aorta run two
other ducts to the bladder, firm and continuous; and there are other
ducts from the hollow of the kidneys, in no way communicating with the
big vein. From the centre of each of the two kidneys springs a
hollow sinewy vein, running along the backbone right through the
loins; by and by each of the two veins first disappears in its own
flank, and soon afterwards reappears stretching in the direction of
the flank. The extremities of these attach to the bladder, and also in
the male to the penis and in the female to the womb. From the big vein
no vein extends to the womb, but the organ is connected with the aorta
by veins numerous and closely packed.
Furthermore, from the aorta and the great vein at the points of
divarication there branch off other veins. Some of these run to the
groins-large hollow veins-and then pass on down through the legs and
terminate in the feet and toes. And, again, another set run through
the groins and the thighs cross-garter fashion, from right to left and
from left to right, and unite in the hams with the other veins.
In the above description we have thrown light upon the course of
the veins and their points of departure.
In all sanguineous animals the case stands as here set forth in
regard to the points of departure and the courses of the chief
veins. But the description does not hold equally good for the entire
vein-system in all these animals. For, in point of fact, the organs
are not identically situated in them all; and, what is more, some
animals are furnished with organs of which other animals are
destitute. At the same time, while the description so far holds
good, the proof of its accuracy is not equally easy in all cases,
but is easiest in the case of animals of considerable magnitude and
supplied abundantly with blood. For in little animals and those
scantily supplied with blood, either from natural and inherent
causes or from a prevalence of fat in the body, thorough accuracy in

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