The term polyclonus has been employed by Murri to designate a succession of clonic contractions of the limbs, due to the existence of punctiform hæmorrhages or areas of softening scattered throughout the rolandic cortex. The character of the motor reaction in these cases, however, bears no resemblance either to tic or to chorea, although the fact of the relation between diffuse cortical lesions and convulsive movements is calculated to enhance the difficulties of diagnosis. Vincenzo Patella[48] has recently called attention to a case of polyclonus in which the disappearance of the symptoms during sleep suggested their purely functional origin, but histological examination of the rolandic grey matter at a subsequent period revealed the presence of numerous foci of degeneration. We are as yet, however, far from grasping the real meaning of such symptoms, which, moreover, from the clinical standpoint, cannot always be assimilated to those of the tics. Conclusive anatomical information is therefore still being awaited. The functional nature of the movements we have had under discussion is unfortunately an obstacle in the way of our early knowledge of their pathology. As long as we remain ignorant of the actual cause of the neuroses and psychoses, so long will the pathological anatomy of tic continue a sealed book. All that has been written on this topic hitherto really concerns spasm and other convulsive affections secondary to irritation of nerve centres or conductors. If we may venture to express an opinion, it is that we should not be surprised if post-mortem examination rest constantly negative. As a matter of fact, we do not favour the view that the phenomena depend on an acquired lesion; rather are we inclined to believe that they represent some congenital anomaly, some arrest or defect in the development of cortical association paths or subcortical anastomoses, minute teratological malformations that our medical knowledge is still unhappily powerless to appreciate. CHAPTER VII STUDY OF THE MOTOR REACTION The general characters of the motor reaction constituting the objective manifestation of tic form the subject of previous analysis in the chapter on pathological physiology. It is our present intention to approach them from the semiological point of view. To give a description of the motor disturbance of universal applicability is evidently to attempt the impossible. The modifications of functional acts are legion, and in the case of tic anomalies of muscular contraction vary not merely with the individual, but in the individual. Each tics after his own fashion; and no two tics are ever exactly interchangeable. As Trousseau was wont to say, "the disease in a sense forms part of the constitution of the person affected." THE TYPE OF MOTOR REACTION--CLONIC TIC AND TONIC TIC