liver blood,
the renal veins (r.v.), from the kidneys, the ilaeo-lumbar, from the
abdominal wall, and the external (e.il.v.) and internal ilias (i.il.v.);
with the exception of the renal veins none of these run side by side
with arteries. The superior cavae (r. and l.v.c.s.) are formed by the
union of internal (i.j.) and external jugular (e.j.) veins with a
subclavian (s.cl.v.) from the fore limb. The term pre-caval vein is
sometimes used for superior cava. The attention, of the student is called
to the small azygos vein (az.) running into the right vena cava superior,
and forming the only asymmetrical (not-balancing) feature of the veins
in front of the heart; it brings blood back from the ribs of the thorax
wall, and is of interest mainly because it answers to an enormous
main vessel, the right post-cardinal sinus, in fishes. There are
spermatic arteries and veins (s.v. and a.) to the genital organs. All
these vessels should be patiently dissected out by the student, and
drawn.

Section 47. Between the final branches of the arteries and the first
fine factors of the veins, and joining them, come the systemic
capillaries. These smallest and ultimate ramifications of the
circulation penetrate every living part of the animal, so that if we
could isolate the vascular system we should have the complete form
of the rabbit in a closely-meshed network. It is in the capillaries that
the exchange of gases occurs and that nutritive material passes out
to the tissues and katastases in from them; they are the essential
factor in the circulatory system of the mammal-- veins, arteries, and
heart simply exist to remove and replace their contents. The details of
the branching of the pulmonary artery and the pulmonary veins need
not detain us now.

Section 48. Summarising the course of the circulation, starting from
the right ventricle, we have-- pulmonary artery, pulmonary capillaries,
pulmonary vein, left auricle, left ventricle, aorta, arteries, and systemic
capillaries. After this, from all parts except the spleen and alimentary
canal, the blood returns to systemic veins, superior or inferior cavae,
right auricle, and right ventricle. The blood from the stomach spleen,
and intestines however, passes via {through} the portal vein to the liver
capillaries and then through the hepatic vein to inferior cava, and so
on. Material leaves the blood to be excreted in lungs, kidneys, by the
skin (as perspiration), and elsewhere. New m