A little girl, Th., ten years of age, takes four or five perfectly normal paces when she starts to walk, then bends down quickly to the right, flexing her knee to an acute angle and inclining her trunk forward with the deflection of her pelvis, just as a child whose genuflexion in front of an altar has become mechanical by repetition. The performance is sometimes so altogether sudden that Th. actually falls on to her right side. One striking feature of the case is that if she makes a tour of the room in order to be observed at leisure, the inclination never fails to occur at exactly the same point in the circuit--namely, when she is opposite the observer. It is useless formally to interdict her from this routine, for before one has time to notice any irregularity in the gait her knee suddenly flexes at the bidding of an invincible impulse, and a moment later, without any deviation from her path, she has resumed her rhythmical step round the apartment. This movement is not her only one, however. While she lies in bed she can, by flexing her thigh on her pelvis, crack her joints loud enough to be heard, and when she has been up a little while the same action is exhibited. The absence of these cracking sounds during ordinary walking, and their occurrence in the act of genuflexion, very properly explain, as Oddo thinks, the origin of the tic. It seems that the articulations at hip and knee on the right side were affected as the result of successive attacks of scarlatina and diphtheria two years ago, which necessitated a prolonged sojourn in bed, and were accompanied with severe pain. It is interesting to note that the tic made its appearance only after the latter had considerably subsided. Raymond and Janet[106] have reported the case of a young woman who fell on her knees every few paces, rising again with facility and taking a few more steps, to come down on her knees once more with a loud noise. She never did herself any harm, however, and for that matter the accident never occurred on a staircase or in a unsuitable or dangerous spot. Leaping tics are met with also. Sometimes when walking, but more usually when standing quietly, according to Guinon, the patients make little jumps or leaps in their place, looking rather as if they were dancing than really springing into the air. Some actually bound along, others run for a yard or two. Still more bizarre and complex tics have been described, in particular by Gilles de la Tourette. One patient used to commence to run, then kneel suddenly, then rise with equal abruptness. Another was in the habit of stooping down, as if to pick something off the ground, and smartly rising again.