From a general point of view, the deductions are entirely reasonable. There is a suggestive analogy between these conditions and the muscular dystrophies in the persistence with which their multiplicity seems to defy the efforts of classification. The analytic stage witnessed the rapid evolution of such clinical types as the facial, the facio-scapulo-humeral, the juvenile, the pseudo-hypertrophic, not to mention others that bear the name of their observer; but it has been succeeded by the synthetic stage, whose function it is to incorporate all the former myopathies in the comprehensive group of "muscular dystrophy." Yet here, again, peril lurks in too hasty a generalisation. To give the disease a name is not equivalent to pronouncing a diagnosis. The denominations "myoclonus," "muscular dystrophy," "degenerate," are alike inconvenient. Their scope is at once too inclusive and too exclusive. They may be indispensable; they are assuredly not sufficient. The possibilities of misapprehension do not end here. The manifestation of each and every tic--be it a flicker of the eyelid, a turn of the head, a cry, a cough--is through the medium of a muscular contraction. On the very nature of this contraction opinion is divided. To its distinctive features of abruptness and momentariness is due the epithet "convulsive" habitually assigned it, but the qualification is not secure. Since the time of Willis the word convulsion has been employed in a double sense, to signify _clonic_ muscular contractions (the "convulsion" of popular parlance) and _tonic_ muscular contractions (a meaning attached to the term only by the scientist). For our part, we can raise no valid objection to the specification of tics as convulsive, provided always that the existence of clonic convulsive tics and of tonic convulsive tics be recognised. As a matter of fact, clinical observation supplies instances of both sorts. Nevertheless, attention has been confined by a majority of authors to the consideration of the former variety only, so much so that a whole order of facts which in derivation, essence, and external characteristics ought to be identified with the tics has been passed over in silence. Even on the assumption that the proposal to recognise the two classes cannot be entertained, at the least it is advisable to predetermine the import of the word convulsion, and to speak of _clonic_ convulsive tics. This is the formula of Ferrand and Widal in their article "Convulsion" in the _Encyclopædic Dictionary of the Medical Sciences_. Similarly, Troisier[6] says that the convulsive tic properly so called is characterised by clonic movements, in which opinion Erb and most German observers concur. Tonic tic appears to have been forgotten, and we have thought it our duty to resuscitate it. Cruchet has quite recently approached the subject in a critical fashion: