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.

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.

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 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.

The third pair

extends from the temples, through the neck,
in underneath the shoulder-blades, into the lung; those from right
to left going in underneath the breast and on to the spleen and the
kidney; those from left to right running from the lung in underneath
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.'

Such are

the accounts given by Syennesis and Diogenes. Polybus
writes to the following effect:-

'There are four pairs of veins. The first extends from the back of
the head, through the neck on the outside, past the backbone on either
side, until it reaches the loins and passes on to the legs, after
which it goes on through the shins to the outer side of the ankles and
on to the feet. And it is on this account that surgeons, for pains
in the back and loin, bleed in the ham and in the outer side of the
ankle. Another pair of veins runs from the head, past ears, through
the neck; which veins are termed the jugular veins. This pair goes
on inside along the backbone, past the muscles of the loins, on to the
testicles, and onwards to the thighs, and through the inside of the
hams and through the shins down to the inside of the ankles and to the
feet; and for this reason, surgeons, for pains in the muscles of the
loins and in the testicles, bleed on the hams and the inner side of
the ankles.

'There is also another pair running on each side through the
spinal marrow to the testicles, thin and delicate. There is,
further, a pair running a little underneath the cuticle through the
flesh to the kidneys, and these with men terminate at the testicle,
and with women at the womb. These veins are termed the spermatic
veins. The veins that leave the stomach are comparatively broad just
as they leave; but they become gradually thinner, until they change
over from right to left and from left to right.

'Blood is thickest when it is imbibed by the fleshy parts; when
it is transmitted to the organs above-mentioned, it becomes thin,
warm, and frothy.'

and from either

one of the two there extend veins in
underneath the shoulder blade and towards the hands; and these
appear alongside the veins splenitis and hepatitis as another pair
of veins smaller in size. When there is a pain near the surface of the
body, the physician lances these two latter veins; but when the pain
is within and in the region of the stomach he lances the veins
splenitis and hepatitis. And from these, other veins depart to run
below the breasts.

'The veins that run through the throat to the head can be
discerned and traced in the neck as large ones; and from each one of
the two, where it terminates, there branch off a number of veins to
the head; some from the right side towards the left, and some from the
left side towards the right; and the two veins terminate near to
each of the two ears. There is another pair of veins in the neck
running along the big vein on either side, slightly less in size
than the pair just spoken of, and with these the greater part of the
veins in the head are connected. This other pair runs through the
throat inside;

Each of the pair

splits at its extremity; the one
branches in the direction of the thumb and the other in the
direction of the palm; and from these run off a number of minute veins
branching off to the fingers and to all parts of the hand. Other
veins, more minute, extend from the main veins; from that on the right
towards the liver, from that on the left towards the spleen and the
kidneys. The veins that run to the legs split at the juncture of the
legs with the trunk and extend right down the thigh. The largest of
these goes down the thigh at the back of it, and can be discerned
and traced as a big one; the second one runs inside the thigh, not
quite as big as the one just mentioned. After this they pass on
along the knee to the shin and the foot (as the upper veins were
described as passing towards the hands), and arrive at the sole of the
foot, and from thence continue to the toes. Moreover, many delicate
veins separate off from the great veins towards the stomach and
towards the ribs.

'The veins in man are as follows:-There are two veins
pre-eminent in magnitude. These extend through the belly along the
backbone, one to right, one to left; either one to the leg on its
own side, and upwards to the head, past the collar bones, through
the throat. From these, veins extend all over the body, from that on
the right hand to the right side and from that on the left hand to the
left side; the most important ones, two in number, to the heart in the
region of the backbone; other two a little higher up through the chest
in underneath the armpit, each to the hand on its side: of these
two, one being termed the vein splenitis, and the other the vein
hepatitis.

'The big veins run thus:-from the navel across the loins, along
the back, past the lung, in under the breasts; one from right to left,
and the other from left to right; that from the left, through the
liver to the kidney and the testicle, that from the right, to the
spleen and kidney and testicle, and from thence to the penis.'
Diogenes of Apollonia writes thus:-

The parts,

then, in animals that are not homogeneous with
themselves and uniform in their texture, both parts external and parts
internal, have the properties above assigned to them.

2

In sanguineous animals the homogeneous or uniform part most
universally found is the blood, and its habitat the vein; next in
degree of universality, their analogues, lymph and fibre, and, that
which chiefly constitutes the frame of animals, flesh and whatsoever
in the several parts is analogous to flesh; then bone, and parts
that are analogous to bone, as fish-bone and gristle; and then, again,
skin, membrane, sinew, hair, nails, and whatever corresponds to these;
and, furthermore, fat, suet, and the excretions: and the excretions
are dung, phlegm, yellow bile, and black bile.

Now, as the nature of blood and the nature of the veins have
all the appearance of being primitive, we must discuss their
properties first of all, and all the more as some previous writers
have treated them very unsatisfactorily. And the cause of the
ignorance thus manifested is the extreme difficulty experienced in the
way of observation. For in the dead bodies of animals the nature of
the chief veins is undiscoverable, owing to the fact that they
collapse at once when the blood leaves them; for the blood pours out
of them in a stream, like liquid out of a vessel, since there is no
blood separately situated by itself, except a little in the heart, but
it is all lodged in the veins. In living animals it is impossible to
inspect these parts, for of their very nature they are situated inside
the body and out of sight. For this reason anatomists who have carried
on their investigations on dead bodies in the dissecting room have
failed to discover the chief roots of the veins, while those who
have narrowly inspected bodies of living men reduced to extreme
attenuation have arrived at conclusions regarding the origin of the
veins from the manifestations visible externally. Of these
investigators, Syennesis, the physician of Cyprus, writes as follows:-

Further, there is the following diversity observable in wombs as
compared with one another: namely that the females of horned
nonambidental animals are furnished with cotyledons in the womb when
they are pregnant, and such is the case, among ambidentals, with the
hare, the mouse, and the bat; whereas all other animals that are
ambidental, viviparous, and furnished with feet, have the womb quite
smooth, and in their case the attachment of the embryo is to the
womb itself and not to any cotyledon inside it.

However, the

differences in respect to the wombs of these fishes as compared with
others of their own species or with fishes in general, would be more
satisfactorily studied in their various forms in specimens under
dissection.

The members of the serpent genus also present divergencies either
when compared with the above-mentioned creatures or with one
another. Serpents as a rule are oviparous, the viper being the only
viviparous member of the genus. The viper is, previously to external
parturition, oviparous internally; and owing to this perculiarity
the properties of the womb in the viper are similar to those of the
womb in the selachians. The womb of the serpent is long, in keeping
with the body, and starting below from a single duct extends
continuously on both sides of the spine, so as to give the
impression of thus being a separate duct on each side of the spine,
until it reaches the midriff, where the eggs are engendered in a
row; and these eggs are laid not one by one, but all strung
together. (And all animals that are viviparous both internally and
externally have the womb situated above the stomach, and all the
ovipara underneath, near to the loin. Animals that are viviparous
externally and internally oviparous present an intermediate
arrangement; for the underneath portion of the womb, in which the eggs
are, is placed near to the loin, but the part about the orifice is
above the gut.)

The properties

of the womb are similar in oviparous quadrupeds, as
the tortoise, the lizard, the frog and the like; for the tube below is
single and fleshy, and the cleft portion with the eggs is at the top
close to the midriff. With animals devoid of feet that are
internally oviparous and viviparous externally, as is the case with
the dogfish and the other so-called Selachians (and by this title we
designate such creatures destitute of feet and furnished with gills as
are viviparous), with these animals the womb is bifurcate, and
beginning down below it extends as far as the midriff, as in the
case of birds. There is also a narrow part between the two horns
running up as far as the midriff, and the eggs are engendered here and
above at the origin of the midriff; afterwards they pass into the
wider space and turn from eggs into young animals.

The womb of birds has the lower and tubular portion fleshy and
firm, and the part close to the midriff membranous and exceedingly
thin and fine: so thin and fine that the eggs might seem to be outside
the womb altogether. In the larger birds the membrane is more
distinctly visible, and, if inflated through the tube, lifts and
swells out; in the smaller birds all these parts are more indistinct.