th more
or less violent involuntary movements, is characteristic of epilepsy.
Involuntary movements without loss of consciousness constitute the
disorder commonly known as _St. Vitus's Dance_. It is rare in early
childhood, becomes more common after the age of five, and attains its
greatest frequency between the ages of ten and fifteen, girls, owing to
their more impressionable nervous system, being affected by it more than
twice as often as boys.

It seldom comes on in a child previously in perfect health, and
strangely enough it occurs with special frequency in children who have
before suffered from rheumatism. Sudden shock or fright is often said to
have been its exciting cause; but even then the symptoms seldom come at
once, but are gradually developed in the course of two or three days. At
first, it is noticed that the child has certain odd fidgety movements,
usually of one arm, next of the leg of the same side, so that it
stumbles in walking, and then the muscles of the face become affected,
the child grimacing strangely, and next the limbs of the opposite side
become involved, and as things go on from bad to worse, the child
becomes unable to hold anything in its hand, to walk, or even to stand,
and even if on the ground still writhes about with the strangest
contortions of its body. If matters grow still worse, the child becomes
unable to put out its tongue, it swallows with difficulty, it loses not
only the power of distinct articulation but even the faculty of speech,
while the mind itself becomes weakened, the child seems half idiotic,
and even though the movements lessen in violence, power over the limbs
is lost for the time, and they seem almost paralysed. Happily cases so
severe are very rare, and it is rarer still for them to have a fatal
termination. Almost invariably recovery takes place by degrees, the
movements lessen, swallowing is performed with less difficulty, the
power of speech, returns, and the intellect regains its brightness: but
the child is left with a special liability to return of the affection,
though the first attack is usually the most severe.

Even at the best, however, the disorder is always tedious, as is shown
by the fact that its average duration is seventy days. It is very
natural, therefore, that parents should be anxious when they see that
their child has some awkward or ungainly habit, some odd trick or
gesture never noticed before, lest it should be the beginning of this
te