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Pages of History of Animals

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History of Animals   

towards the backbone and the last vertebra of the neck.
The vessel, then, that extends to the lung, as the lung itself
is duplicate, divides at first into two; and then extends along by
every pipe and every perforation, greater along the greater ones,
lesser along the less, so continuously that it is impossible to
discern a single part wherein there is not perforation and vein; for
the extremities are indistinguishable from their minuteness, and in
point of fact the whole lung appears to be filled with blood.
The branches of the blood-vessels lie above the tubes that
extend from the windpipe. And that vessel which extends to the
vertebra of the neck and the backbone, stretches back again along
the backbone; as Homer represents in the lines:-

(Antilochus, as Thoon turned him round),
Transpierc'd his back with a dishonest wound;
The hollow vein that to the neck extends,
Along the chine, the eager javelin rends.

From this vessel there extend small blood-vessels at each rib
and each vertebra; and at the vertebra above the kidneys the vessel
bifurcates. And in the above way the parts branch off from the great
But up above all these, from that part which is connected with the
heart, the entire vein branches off in two directions. For its
branches extend to the sides and to the collarbones, and then pass on,
in men through the armpits to the arms, in quadrupeds to the forelegs,
in birds to the wings, and in fishes to the upper or pectoral fins.
(See diagram.) The trunks of these veins, where they first branch
off, are called the 'jugular' veins; and, where they branch off to
the neck the great vein run alongside the windpipe; and,
occasionally, if these veins are pressed externally, men, though not
actually choked, become insensible, shut their eyes, and fall flat on
the ground. Extending in the way described and keeping the windpipe
in betwixt them, they pass on until they reach the ears at the
junction of the lower jaw with the skull. Hence again they branch off
into four veins, of which one bends back and descends through the
neck and the shoulder, and meets the previous branching off of the
vein at the bend of the arm, while the rest of it terminates at the
hand and fingers. (See diagram.)
Each vein of the other pair stretches from the region of the ear
to the brain, and branches off in a number of fine and delicate
veins into the so-called meninx, or membrane, which surrounds the
brain. The brain itself in all animals is destitute of blood, and no
vein, great or small, holds its course therein. But of the remaining
veins that branch off from the last mentioned vein some envelop the
head, others close their courses in the organs of sense and at the
roots of the teeth in veins exceedingly fine and minute.

And in like manner the parts of the lesser one of the two chief
blood-vessels, designated the aorta, branch off, accompanying the
branches from the big vein; only that, in regard to the aorta, the
passages are less in size, and the branches very considerably less
than are those of the great vein. So much for the veins as observed in
the regions above the heart.
The part of the great vein that lies underneath the heart
extends, freely suspended, right through the midriff, and is united
both to the aorta and the backbone by slack membranous communications.
From it one vein, short and wide, extends through the liver, and
from it a number of minute veins branch off into the liver and
disappear. From the vein that passes through the liver two branches
separate off, of which one terminates in the diaphragm or so-called
midriff, and the other runs up again through the armpit into the right
arm and unites with the other veins at the inside of the bend of the

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