notion now-a-days; but if anybody will look at the facts he will see
that it is a very probable supposition. There is a great vein (hepatic
vein--Fig. 1) which rises out of the liver, and that vein goes straight
into the 'vena cava' (Fig. 1) which passes to the heart, being there
joined by the other veins of the body. The liver itself is fed by a
very large vein (portal vein--Fig. 1), which comes from the alimentary
canal. The way the ancients looked at this matter was, that the food,
after being received into the alimentary canal, was then taken up by the
branches of this great vein, which are called the 'vena portae', just
as the roots of a plant suck up nourishment from the soil in which it
lives; that then it was carried to the liver, there to be what was
called "concocted," which was their phrase for its conversion into
substances more fitted for nutrition than previously existed in it.
They then supposed that the next thing to be done was to distribute
this fluid through the body; and Galen like his predecessors, imagined
that the "concocted" blood, having entered the great 'vena cava', was
distributed by its ramifications all over the body. So that, in his
view (Fig. 2), the course of the blood was from the intestine to the
liver, and from the liver into the great 'vena cava', including what we
now call the right auricle of the heart, whence it was distributed by
the branches of the veins. But the whole of the blood was not thus
disposed of. Part of the blood, it was supposed, went through what we
now call the pulmonary arteries (Fig. 1), and, branching out there, gave
exit to certain "fuliginous" products, and at the same time took in
from the air a something which Galen calls the 'pneuma'. He does not
know anything about what we call oxygen; but it is astonishing how very
easy it would be to turn his language into the equivalent of modern
chemical theory. The old philosopher had so just a suspicion of the
real state of affairs that you could make use of his language in many
cases, if you substituted the word "oxygen," which we now-a-days use,