tendency to various purposeless movements, and to the utterance of
various sounds. We see this in our young children, in their loud
laughter, clapping of hands, and jumping for joy; in the bounding and
barking of a dog when going out to walk with his master; and in the
frisking of a horse when turned out into an open field. Joy quickens
the circulation, and this stimulates the brain, which again reacts on
the whole body. The above purposeless movements and increased
heart-action may be attributed in chief part to the excited state of
the sensorium,[310] and to the consequent undirected overflow, as Mr.
Herbert Spencer insists, of nerve-force. It deserves notice, that it is
chiefly the anticipation of a pleasure, and not its actual enjoyment,
which leads to purposeless and extravagant movements of the body, and
to the utterance of various sounds. We see this in our children when
they expect any great pleasure or treat; and dogs, which have been
bounding about at the sight of a plate of food, when they get it do not
show their delight by any outward sign, not even by wagging their
tails. Now with animals of all kinds, the acquirement of almost all
their pleasures, with the exception of those of warmth and rest, are
associated, and have long been associated with active movements, as in
the hunting or search for food, and in their courtship. Moreover, the
mere exertion of the muscles after long rest or confinement is in
itself a pleasure, as we ourselves feel, and as we see in the play of
young animals. Therefore on this latter principle alone we might
perhaps expect, that vivid pleasure would be apt to show itself
conversely in muscular movements.
With all or almost all animals, even with birds, Terror causes the body
to tremble. The skin becomes pale, sweat breaks out, and the hair
bristles. The secretions of the alimentary canal and of the kidneys are
increased, and they are involuntarily voided, owing to the relaxation
of the sphincter muscles, as is known to be the case with man, and as I
have seen with cattle, dogs, cats, and monkeys. The breathing is
hurried. The heart beats quickly, wildly, and violently; but whether it
pumps the blood more efficiently through the body may be doubted, for
the surface seems bloodless and the strength of the muscles soon fails.
In a frightened horse I have felt through the saddle the beating of the
heart so plainly that I could have counted the beats. The mental
faculties are much disturbed. Utter prostration soon follows, and even
fainting. A terrified canary-bird has been seen not only to tremble and
to turn white about the base of the bill, but to faint;[311] and I once
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