Now that was a very
remarkable and striking discovery.
But it is not given to any man to be altogether right (that is a
reflection which it is very desirable for every man who has had the
good luck to be nearly right once, always to bear in mind); and
Erasistratus, while he made this capital and important discovery, made a
very capital and important error in another direction, although it was
a very natural error. If, in any animal which is recently killed, you
open one of those pulsating trunks which I referred to a short time
ago, you will find, as a general rule, that it either contains no blood
at all or next to none; but that, on the contrary, it is full of air.
Very naturally, therefore, Erasistratus came to the conclusion that
this was the normal and natural state of the arteries, and that they
contained air. We are apt to think this a very gross blunder; but, to
anybody who is acquainted with the facts of the case, it is, at first
sight, an exceedingly natural conclusion. Not only so, but Erasistratus
might have very justly imagined that he had seen his way to the meaning
of the connection of the left side of the heart with the lungs; for we
find that what we now call the pulmonary vein is connected with the
lungs, and branches out in them (Fig.
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