Medicine

M. Charcot directs attention to tlie importance of the distinction of cases of tremors into two classes or groups: the first comprehending those cases in which tremors occur only during an intentional or voluntary movement; the second including the cases in which the tremors are constant, or at least cease only during sleep. The latter group constitutes the paralysis agitans. In each group there are numerous species, presenting considerable differences. This distinction of the convulsive tremor (tremor coaclus) from the simple trembling due to weakness (tremor a debilitate), is mentioned by Galen, and was insisted on by the medical writers of last century; but, notwithstanding its importance, was, till recently, overlooked by modern authors. Gubler has shown that the spasmodic tremors are often due to alternate jerking contractions and relaxations of the muscles, by which movements are affected, or the