The tic of this paper, be it understood, is not tic douloureux or trifacial neuralgia, but painless and purely motor tic, sometimes called "convulsive tic," but generally just "tic." There being no really good English term for the disorder, the French word has been almost universally adopted. "Habit spasm" is perhaps the best that we have, but the trouble is more than a habit, less than a spasm, or rather not a spasm at all. Tic belongs to the hyperkinesias; that is, it is a disorder of movement pathologic in its excess or exuberance. It is a motor obsession, an imperative impulsion voicing itself in movement. Although chorea has little in common with tic except excess of movement, the latter is not infrequently mistaken for the former. This fact is the only justification for the following trite remarks.
The movements of chorea are involuntary and not amenable to control by