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History of Animals   


the breast and into the liver and the kidney; and both terminate in
the fundament. The fourth pair extend from the front part of the
head and the eyes in underneath the neck and the collar-bones; from
thence they stretch on through the upper part of the upper arms to the
elbows and then through the fore-arms on to the wrists and the
jointings of the fingers, and also through the lower part of the
upper-arms to the armpits, and so on, keeping above the ribs, until
one of the pair reaches the spleen and the other reaches the liver;
and after this they both pass over the stomach and terminate at the
penis.'
The above quotations sum up pretty well the statements of all
previous writers. Furthermore, there are some writers on Natural
History who have not ventured to lay down the law in such precise
terms as regards the veins, but who all alike agree in assigning the
head and the brain as the starting-point of the veins. And in this
opinion they are mistaken.
The investigation of such a subject, as has been remarked, is one
fraught with difficulties; but, if any one be keenly interested in the
matter, his best plan will be to allow his animals to starve to
emaciation, then to strangle them on a sudden, and thereupon to
prosecute his investigations.
We now proceed to give particulars regarding the properties and
functions of the veins. There are two blood-vessels in the thorax by
the backbone, and lying to its inner side; and of these two the larger
one is situated to the front, and the lesser one is to the rear of it;
and the larger is situated rather to the right hand side of the
body, and the lesser one to the left; and by some this vein is
termed the 'aorta', from the fact that even in dead bodies part of
it is observed to be full of air. These blood-vessels have their
origins in the heart, for they traverse the other viscera, in whatever
direction they happen to run, without in any way losing their
distinctive characteristic as blood-vessels, whereas the heart is as
it were a part of them (and that too more in respect to the
frontward and larger one of the two), owing to the fact that these two
veins are above and below, with the heart lying midway.
The heart in all animals has cavities inside it. In the case of
the smaller animals even the largest of the chambers is scarcely
discernible; the second larger is scarcely discernible in animals of
medium size; but in the largest animals all three chambers are
distinctly seen. In the heart then (with its pointed end directed
frontwards, as has been observed) the largest of the three chambers is
on the right-hand side and highest up; the least one is on the
left-hand side; and the medium-sized one lies in betwixt the other
two; and the largest one of the three chambers is a great deal
larger than either of the two others. All three, however, are
connected with passages leading in the direction of the lung, but
all these communications are indistinctly discernible by reason of
their minuteness, except one.
The great blood-vessel, then, is attached to the biggest of the
three chambers, the one that lies uppermost and on the right-hand
side; it then extends right through the chamber, coming out as
blood-vessel again; just as though the cavity of the heart were a part
of the vessel, in which the blood broadens its channel as a river that
widens out in a lake. The aorta is attached to the middle chamber;
only, by the way, it is connected with it by much narrower pipe.
The great blood-vessel then passes through the heart (and runs
from the heart into the aorta). The great vessel looks as though
made of membrane or skin, while the aorta is narrower than it, and
is very sinewy; and as it stretches away to the head and to the
lower parts it becomes exceedingly narrow and sinewy.
First of all, then, upwards from the heart there stretches a
part of the great blood-vessel towards the lung and the attachment
of the aorta, a part consisting of a large undivided vessel. But there
split off from it two parts; one towards the lung and the other

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