nd it was probably after they had been hunted to
death that he examined them. Now, it is generally admitted that
coagulation under such circumstances is imperfect and even uncommon. The
statement as to the richness in fibres of the blood of bulls and boars
has been confirmed by some modern investigations, which have shown that
the clot bears a proportion to the strength and ferocity of the animal.
The remarks, however, as to the relative rapidity of coagulation would
appear to be contradicted by later observations, for Thackrah came to
the conclusion that coagulation commenced sooner in small and weak
animals than in strong.

Of the _brain_ Aristotle makes the following among other assertions: "Of
all parts of the body there is none so cold as the brain.... Of all the
fluids of the body it is the one that has the least blood, for, in fact,
it has no blood at all in its proper substance.... That it has no
continuity with the organs of sense is plain from simple inspection, and
still more closely shown by the fact that when it is touched no
sensation is produced.... The brain tempers the heat and seething of the
heart.... In order that it may not itself be absolutely without heat,
blood-vessels from the aorta end in the membrane which surrounds the
brain.... Of all animals man has the largest brain in proportion to his
size: and it is larger in men than in women. This is because the region
of the heart and of the lung is hotter and richer in blood in man than
in any other animal; and in men than in women. This again explains why
man alone of animals stands erect. For the heat, overcoming any opposite
inclination, makes growth take its own line of direction, which is from
the centre of the body upwards.... Man again has more sutures in his
skull than any other animal, and the male more than the female. The
explanation is to be found in the greater size of the brain, which
demands free ventilation proportionate to its bulk.... There is no brain
in the hinder part of the head.... The brain in all animals that have
one is placed in the front part of the head ... because the heart, from
which sensation proceeds, is in the front part of the body."

Although it would perhaps be difficult to find anywhere as many errors
in as few words, yet it should be observed that Aristotle here shows
himself to have been aware of the existence of the membranes of the
brain--the _pia mater_ and the _dura mater_; and elsewhere[7] he says
more