=St. Vitus's Dance.=--A state of unconsciousness, accompanied with 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.