Localized cortical irritative phenomena occupy a most respected place in the attention of neurologists. Rightfully so, for it was from the study of such cases that cortical localization began and the way was paved for the present knowledge of cerebral cortical physiology. So that today, in patients who present symptoms of an irritative nature of the motor or sensory areas of the brain, correct localization is as certain as scientific diagnosis permits. The exact type of lesion is not so easily surmised as the location, which problem prompted this study of some 130 cases presenting localizing epileptiform attacks. The literature is replete with reports of groups and single cases of jacksonian epilepsy as a result of injury to the cerebrum. There are also reported numbers of cases with localized motor or sensory attacks occurring in intracranial neoplasms. The location of these tumors has been both cortical and subcortical. Numbers of