Our lack of knowledge concerning the precise localisation of these functional centres is paralleled by our ignorance as to the manner of their involvement. Noir has prudently observed that the manifestation of co-ordinated tics in cases of widespread cerebral disease, and the frequent occurrence of the most extensive and complex varieties in patients who have suffered from meningeal affections, suggest their cerebral origin. On these points, however, anatomo-pathological information is to seek, and for that matter the direct dependence of such an habitual movement as a co-ordinated tic upon one lesion is scarcely within the bounds of probability. Tic pertains to a psychical rather than to a motor sphere, and is to be regarded as a disease of the will. With this statement, and with the expression of our hope that subsequent work will aid in the elucidation of the question, we shall close the chapter of the tic's pathological anatomy. It may not prove superfluous, however, to indicate why and how the facts gleaned from pathology and supposed to be in harmony with the clinical picture of tic should be allocated to other morbid entities. In several cases considered to be tics of the face, cortical lesions have been discovered at the posterior end of the second frontal convolution, in the centre for voluntary and co-ordinated movements of the contra-lateral facial muscles. It has become classical to cite an example described as long ago as 1864 by Debrou[41] under the title "painless facial tic," but a glance at the observation suffices at once to negative its classification as a tic, and to justify the diagnosis of a spasm of a quite peculiar sort.