A not infrequent accessory symptom--viz. elevation of the corresponding shoulder--may have a similar origin in peripheral excitation connected with the patient's clothing. To escape the annoyance of a high and narrow collar, or, on the other hand, to experience an agreeable sensation by rubbing the skin, it is a very simple and a very easy matter to lean the head on the shoulder, and to raise the latter at the same time. The automatic reproduction of this gesture eventually ends in the formation of a tic which removal of the collar entirely fails to suppress. The first therapeutic indication, nevertheless, is to interdict the wearing of the unsuitable collar, and to recommend the adoption of others softer and more ample. Whatever be the opinion one holds on the mechanism of tic, the influence of peripheral stimuli is, according to Pierre Marie,[77] very considerable, and it is his invariable practice, in the case of youthful subjects, to impress on the parents the desirability of paying special attention to their children's clothing, and of discarding any article that is either stiff or heavy. In one of our cases, a girl A., suffering from a nodding and rotatory tic of the head, examination of the cervical region revealed the existence of a line of cicatrices along the margin of the sternomastoid, the vestiges of a previous operation for a severe tuberculous adenitis. Some nerve filaments entering the sternomastoid and trapezius had no doubt been cut, since these muscles presented a minor degree of atrophy, and the irritation arising therefrom, as well at that due to dragging on the adhesions between the cicatrices and the underlying tissues, had been the starting-point of a motor reaction primarily convulsive and involuntary, but eventually habitual and automatic, and therefore, with the subsidence of the excitation, a tic. In another case[78] a month's systematic treatment served to curtail to a noteworthy extent spasmodic head movements resembling those one makes to get rid of a fly. From another point of view, some of the tics of this class are merely the exaggeration of certain functions destined for the expression of the ideas of affirmation and negation. The nod of the head with which little G. used to punctuate his "yes's" was logical enough, but he soon began its repetition irrespective of his topic of conversation, and even when saying "no"--a veritable tic of affirmation. Numbers of people are in the habit of emphasising their words with those to-and-fro movements of the head that we call gestures of approval. Now, if the gesture be strictly appropriate to the thought present in the mind, it cannot be identified with the tics. On the other hand, its execution may be inopportune, in which case, provided the form remain normal, it is merely a stereotyped act, and must exhibit the additional features of abruptness and exaggeration ere it rank as a tic.