be looked upon by different people from different points of view. Galen
looked upon these facts from a very different point of view from that
which we ourselves occupy; but, so far as the facts are concerned, they
were the same for him as for us. Well then, the first thing that Galen
did was to make out experimentally that, during life, the arteries are
not full of air, but that they are full of blood. And he describes a
great variety of experiments which he made upon living animals with the
view of proving this point, which he did prove effectually and for all
time; and that you will observe was the only way of settling the matter.
Furthermore, he demonstrated that the cavities of the left side of the
heart--what we now call the left auricle and the left ventricle--are,
like the arteries, full of blood during life, and that that blood was of
the scarlet kind--arterialised, or as he called it "pneumatised," blood.
It was known before, that the pulmonary artery, the right ventricle,
and the veins, contain the darker kind of blood, which was thence called
venous. Having proved that the whole of the left side of the heart,
during life, is full of scarlet arterial blood, Galen's next point
was to inquire into the mode of communication between the arteries
and veins. It was known before his time that both arteries and veins
branched out. Galen maintained, though he could not prove the fact, that
the ultimate branches of the arteries and veins communicated together
somehow or other, by what he called 'anastomoses', and that these
'anastomoses' existed not only in the body in general but also in the
lungs. In the next place, Galen maintained that all the veins of
the body arise from the liver; that they draw the blood thence and
distribute it over the body. People laugh at that 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--Figure 1) which rises
out of the liver, and that vein goes straight into the 'vena cava'
(Figure 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--Figure 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
plan