Gratiolet admits[914] that when a man has to struggle with another to
his utmost, or has to support a great weight, or to keep for a long
time the same forced attitude, it is necessary for him first to make a
deep inspiration, and then to cease breathing; but he thinks that Sir
C. Bell s explanation is erroneous. He maintains that arrested
respiration retards the circulation of the blood, of which I believe
there is no doubt, and he adduces some curious evidence from the
structure of the lower animals, showing, on the one hand, that a
retarded circulation is necessary for prolonged muscular exertion, and,
on the other hand, that a rapid circulation is necessary for rapid
movements. According to this view, when we commence any great exertion,
we close our mouths and stop breathing, in order to retard the
circulation of the blood. Gratiolet sums up the subject by saying,
C est la la vraie theorie de l effort continu; but how far this
theory is admitted by other physiologists I do not know.
Dr. Piderit accounts[915] for the firm closure of the mouth during
strong muscular exertion, on the principle that the influence of the
will spreads to other muscles besides those necessarily brought into
action in making any particular exertion; and it is natural that the
muscles of respiration and of the mouth, from being so habitually used,
should be especially liable to be thus acted on. It appears to me that
there probably is some truth in this view, for we are apt to press the
teeth hard together during violent exertion, and this is not requisite
to prevent expiration, whilst the muscles of the chest are strongly
contracted.
Lastly, when a man has to perform some delicate and difficult
operation, not requiring the exertion of any strength, he nevertheless
generally closes his mouth and ceases for a time to breathe; but he
acts thus in order that the movements of his chest may not disturb,
those of his arms. A person, for instance, whilst threading a needle,
may be seen to compress his lips and either to stop breathing, or to
breathe as quietly as possible. So it was, as formerly stated, with a
young and sick chimpanzee, whilst it amused itself by killing flies
with its knuckles, as they buzzed about on the window-panes. To perform
an action, however trifling, if difficult, implies some amount of
previous determination.
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