which we may call, with a certain latitude of expression, Habit
Spasms. By a habit spasm is meant the constant repetition of an action
which was originally designed to produce some one definite result, but
which has become involuntary, habitual, and separated from its
original meaning. The nervous cough forms a good example of a habit
spasm. A cough may lose its purpose and persist only as a bad habit,
especially in moments of nervousness, as in talking to strangers, in
entering a room, or at the moment of saying "How do you do" or
"Good-bye." Twitching the mouth, swallowing, elongating the upper lip,
biting the lips, wrinkling the forehead so strongly that the whole
scalp may be put into movement, and blepharospasm are all common
tricks of little children which may become habitual and uncontrolled.
In worse cases there may be constant jerking movements of the head,
nodding movements, or even bowing salaam-like movements. In mild
cases we may note hardly more than a restless movement of mouth or
forehead, or constant plucking or writhing of the fingers whenever the
child's attention is aroused, when he is spoken to, or when he himself
speaks. In nervous children these movements, which should properly be
confined to moments of real emotional stress, become habitual, and are
displayed apart from the excitement of particular emotions. Whatever
their intensity, habitual and involuntary movements of this nature
should not be overlooked, and should be regarded as evidence of mental
unrest. They do not commonly appear during the first or second years
of the child's life. They are more frequent after the age of five, but
they may begin to be marked as early as the third year. With refusal
of food and refusal of sleep they form the three common neuroses of
early childhood.

Two of the three qualities which we have mentioned as characteristic
of the child's mind are concerned in the causation of habit spasm. In