During the past few years many investigations have been made, especially by means of Nissl's stain, to determine the changes induced in nerve-cells by various poisons and toxins. The methods of research have been various. Of the great list of toxic agents employed, lead, arsenic, silver nitrate, phosphorus, malonnitril, strychnin, and the toxins of tetanus, rabies and diphtheria may be mentioned as the most important. The most prominent variation from the normal structure in all these cases is chromatolysis, i. e., the solution of the chromophile bodies described by Nissl. The significance of this most wide-spread change is still a disputed question. According to Lugaro1, alterations in the chromatic part of the nerve-cell represent a reaction of the nerve-cell to a disturbing force, and are reparable, a view which is supported by the investigations of Nissl, Nicholas2, Goldscheider and Flatau3 and others, who have produced chromatolysis experimentally, and