Apart from his studies in objective localisation, Trousseau, as we have seen, recognised that the tic subject was mentally abnormal, but the credit of demonstrating the pathogenic significance of the psychical factor is Charcot's. Tic, he declared,[3] was physical only in appearance; under another aspect it was a mental disease, a sort of hereditary aberration. Advance along the lines thus laid down has been the work more especially of Magnan and his pupils, of Gilles de la Tourette, Letulle, and Guinon. A meritorious contribution to the elucidation of the question is the thesis of Julien Noir, written under the inspiration of Bourneville and published in 1893. The still more recent labours of Brissaud, Pitres, and Grasset in France, and of others elsewhere, have added materially to our knowledge. Confining ourselves for the present to the discussion of the latest interpretations put on the word tic, we may be allowed the remark that if the influence of Magnan's teaching has been instrumental in making our idea of tic conform more to the results of observation, nevertheless his view is not without its dangers. In the opinion of Magnan and his pupils, Saury and Legrain[4] in particular, the tics do not form a morbid entity; they are nought else than episodic syndromes of what Morel called "hereditary insanity," that is to say, of what is usually designated nowadays "mental degeneration." Now, if by degeneration be meant a more or less pronounced hereditary psychopathic or neuropathic tendency which betrays itself by actual physical or psychical stigmata, then tic patients are unquestionably degenerates. If degeneration unveils itself in multifarious psychical or physical anomalies, the subjects of the tic are undoubtedly degenerates. If a degenerate may suffer from one or other variety of aboulia, or phobia, or obsession, the man with tic is a degenerate too. Thus understood, the epithet may be applied to all individuals affected with tic. In fact, they _must_ be degenerates, if the word is to be employed in its most comprehensive sense. But the explanation is insufficient, inasmuch as the converse does not hold good; all degenerates do not tic. We may be safe in maintaining, then, that tic is only one of the manifold expressions of mental degeneration, but we are not much enlightened thereby. Obsessions and manias similarly are indications of mental deterioration, yet the fact conveys very scanty information as to their real nature. Physical anomalies--ectrodactyly, for instance--betoken physical degeneration, no doubt; but are inquiries to cease with this categorical assertion? Such certainly was not the idea of those observers whose is the praise for having demonstrated the common parentage of the heterogeneous manifestations of degeneration. Synthesis cannot exclude the work of analysis, and in practice there is scarcely a case to which this doctrine is not pertinent.