The motor reaction may be either _clonic_ or _tonic_ in type. Clonic tics are distinguished by more or less abrupt contractions, separated by longer or shorter intervals of relaxation or repose. The duration of a clonic tic convulsion may be exceedingly brief, though perhaps not so brief as the instantaneous "electric" twitches of a spasm, which have the extreme rapidity of pure reflex phenomena. Exception ought to be made for the face, no doubt, seeing that the suddenness of the movements in facial tic is precisely what complicates the diagnosis between it and facial spasm, as we shall see. In the limbs, the variations appear to stand in close relation to the nature of the primary factor, the mental condition of the patient, and the mode of reaction peculiar to him. The quickness with which the reaction occurs increases in proportion to the length of time the tic has existed, although once it has become habitual, any further change is rather in the direction of additional complexity. Sometimes a relative deliberateness of execution raises suspicions as to the accuracy of the diagnosis. In the case of a child with several tics, one affecting the mouth in particular, Guinon was struck by the slowness of the muscular contractions. To begin with (he says), the mouth was opened gradually, but as soon at the limit of separation of the maxillæ was reached, it was immediately closed, without remaining even for a moment in the extended position, as one would have expected had there been a tonic contraction of the infrahyoid muscles. Cases of this kind, however, are not really instances of the tonic variety. One of us has had the opportunity of observing a young woman afflicted with a curious combination of motor disorders, akin no less to the clonic form of tic than to the gesticulations of chorea and the undulatory movements of athetosis. Their resemblance to the clinical type described by Brissaud under the name of _variable chorea_ is noteworthy, a distinguishing feature, however, being the sluggishness of the muscular contractions, which may well be a reflex of the patient's mental inertness. Mademoiselle R., a young woman twenty-six years old, is a small and delicate creature with slender limbs and tapering fingers. She is extremely myopic, but her general health is excellent, and there is nothing to suggest that she is suffering from organic disease of the nervous system. Apart from the fact that her parents are rather "nervous," the family history is negative.