" This we know from experience in a severe head-
ache. We perceive the pain to be increased by in-
tense study or thinking, and that mental application
determines more blood to the head. So true is it that
mental excitement produces an increased flow of blood
to the head, that surgeons are very careful to pre-
serve a quiet state of mind in those whose heads are
wounded. Sir Astley Cooper, speaking of such inju-
ries, says that if any mental power remains all excite-
ment of the brain should be avoided, and relates the
following case : ' A young gentleman was brought to
me from the north of England who had lost a portion
of his skull just above the eyebrow. On examining
the head I distinctly saw the pulsations of the brain,
which were regular and slow, but at this time he was
agitated by some opposition to his wishes, and di-
rectly the pulsations of the brain were increased, and
became more violent, and more blood rushed to the
brain. Ifj therefore, you omit to keep the mind free

* Mental Exertion in relation to Health. English edition,
London: 1864, p. 20. The American editions, of which there
were several, have long been out of print.
96 CEREBRAL HYPEREMIA.
