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History of Animals   

investigation is not equally attainable; for in the latter of these
creatures the passages get clogged, like water-channels choked with
slush; and the others have a few minute fibres to serve instead of
veins. But in all cases the big vein is plainly discernible, even in
creatures of insignificant size.

The sinews of animals have the following properties. For these
also the point of origin is the heart; for the heart has sinews within
itself in the largest of its three chambers, and the aorta is a
sinew-like vein; in fact, at its extremity it is actually a sinew, for
it is there no longer hollow, and is stretched like the sinews where
they terminate at the jointings of the bones. Be it remembered,
however, that the sinews do not proceed in unbroken sequence from
one point of origin, as do the blood-vessels.
For the veins have the shape of the entire body, like a sketch
of a mannikin; in such a way that the whole frame seems to be filled
up with little veins in attenuated subjects-for the space occupied
by flesh in fat individuals is filled with little veins in thin
ones-whereas the sinews are distributed about the joints and the
flexures of the bones. Now, if the sinews were derived in unbroken
sequence from a common point of departure, this continuity would be
discernible in attenuated specimens.
In the ham, or the part of the frame brought into full play in the
effort of leaping, is an important system of sinews; and another
sinew, a double one, is that called 'the tendon', and others are those
brought into play when a great effort of physical strength is
required; that is to say, the epitonos or back-stay and the
shoulder-sinews. Other sinews, devoid of specific designation, are
situated in the region of the flexures of the bones; for all the bones
that are attached to one another are bound together by sinews, and a
great quantity of sinews are placed in the neighbourhood of all the
bones. Only, by the way, in the head there is no sinew; but the head
is held together by the sutures of the bones.
Sinew is fissile lengthwise, but crosswise it is not easily
broken, but admits of a considerable amount of hard tension. In
connexion with sinews a liquid mucus is developed, white and
glutinous, and the organ, in fact, is sustained by it and appears to
be substantially composed of it. Now, vein may be submitted to the
actual cautery, but sinew, when submitted to such action, shrivels
up altogether; and, if sinews be cut asunder, the severed parts will
not again cohere. A feeling of numbness is incidental only to parts of
the frame where sinew is situated.
There is a very extensive system of sinews connected severally
with the feet, the hands, the ribs, the shoulder-blades, the neck, and
the arms.
All animals supplied with blood are furnished with sinews; but
in the case of animals that have no flexures to their limbs, but
are, in fact, destitute of either feet or hands, the sinews are fine
and inconspicuous; and so, as might have been anticipated, the
sinews in the fish are chiefly discernible in connexion with the fin.

The ines (or fibrous connective tissue) are a something
intermediate between sinew and vein. Some of them are supplied with
fluid, the lymph; and they pass from sinew to vein and from vein to
sinew. There is another kind of ines or fibre that is found in
blood, but not in the blood of all animals alike. If this fibre be
left in the blood, the blood will coagulate; if it be removed or
extracted, the blood is found to be incapable of coagulation. While,
however, this fibrous matter is found in the blood of the great
majority of animals, it is not found in all. For instance, we fail
to find it in the blood of the deer, the roe, the antelope, and some
other animals; and, owing to this deficiency of the fibrous tissue,

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