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History of Animals   

lung. It is attached also to the great vein and to what is
designated the 'aorta'. When the windpipe is charged with air, the air
passes on to the hollow parts of the lung. These parts have divisions,
composed of gristle, which meet at an acute angle; from the
divisions run passages through the entire lung, giving off smaller and
smaller ramifications. The heart also is attached to the windpipe,
by connexions of fat, gristle, and sinew; and at the point of juncture
there is a hollow. When the windpipe is charged with air, the entrance
of the air into the heart, though imperceptible in some animals, is
perceptible enough in the larger ones. Such are the properties of
the windpipe, and it takes in and throws out air only, and takes in
nothing else either dry or liquid, or else it causes you pain until
you shall have coughed up whatever may have gone down.
The oesophagus communicates at the top with the mouth, close to
the windpipe, and is attached to the backbone and the windpipe by
membranous ligaments, and at last finds its way through the midriff
into the belly. It is composed of flesh-like substance, and is elastic
both lengthways and breadthways.
The stomach of man resembles that of a dog; for it is not much
bigger than the bowel, but is somewhat like a bowel of more than usual
width; then comes the bowel, single, convoluted, moderately wide.
The lower part of the gut is like that of a pig; for it is broad,
and the part from it to the buttocks is thick and short. The caul,
or great omentum, is attached to the middle of the stomach, and
consists of a fatty membrane, as is the case with all other animals
whose stomachs are single and which have teeth in both jaws.
The mesentery is over the bowels; this also is membranous and
broad, and turns to fat. It is attached to the great vein and the
aorta, and there run through it a number of veins closely packed
together, extending towards the region of the bowels, beginning
above and ending below.
So much for the properties of the oesophagus, the windpipe, and
the stomach.

The heart has three cavities, and is situated above the lung at
the division of the windpipe, and is provided with a fatty and thick
membrane where it fastens on to the great vein and the aorta. It
lies with its tapering portion upon the aorta, and this portion is
similarly situated in relation to the chest in all animals that have a
chest. In all animals alike, in those that have a chest and in those
that have none, the apex of the heart points forwards, although this
fact might possibly escape notice by a change of position under
dissection. The rounded end of the heart is at the top. The apex is to
a great extent fleshy and close in texture, and in the cavities of the
heart are sinews. As a rule the heart is situated in the middle of the
chest in animals that have a chest, and in man it is situated a little
to the left-hand side, leaning a little way from the division of the
breasts towards the left breast in the upper part of the chest.
The heart is not large, and in its general shape it is not
elongated; in fact, it is somewhat round in form: only, be it
remembered, it is sharp-pointed at the bottom. It has three
cavities, as has been said: the right-hand one the largest of the
three, the left-hand one the least, and the middle one intermediate in
size. All these cavities, even the two small ones, are connected by
passages with the lung, and this fact is rendered quite plain in one
of the cavities. And below, at the point of attachment, in the largest
cavity there is a connexion with the great vein (near which the
mesentery lies); and in the middle one there is a connexion with the
Canals lead from the heart into the lung, and branch off just
as the windpipe does, running all over the lung parallel with the
passages from the windpipe. The canals from the heart are uppermost;
and there is no common passage, but the passages through their

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