(_c_) Lesion of the brachial centre (2) and of its associated fasciculus is made known by spasm or paralysis, or by both in succession, in the hand and arm. In many cases (tumor especially) the first symptom is clonic convulsive movements of two or more fingers, extending to other parts of the arm. Such brachial monospasm or monoplegia is usually accompanied or followed by incomplete hemiplegia. (_d_) Lesion of the crural centre (3) in the paracentral lobule and of its associated fasciculus of white substance is indicated by priority and predominance of convulsive and paralytic phenomena in the foot and leg: a crural monospasm or monoplegia exists with or without incomplete hemiplegia. The positive diagnosis of these separate localizations is most feasible in cases of tumors or of cranial injury where the initial lesion is limited in extent and where the morbid process is for a time localized. As a rule, localized spasm (Jacksonian epilepsy) without loss of consciousness is the first symptom, followed after a time by localized paralysis (always in the same muscular groups); and later still the symptom-group becomes obscured by the supervention of other symptoms indicating extension of disease to other parts of the kinesodic system, or even to the æsthesodic system. (_e_) Lesion of the insula and adjacent white substance laterad of the nucleus lenticularis (5) may be suspected from the rapid or sudden development of symptoms imitating those of acute bulbar paralysis, but {89} without bilateral paresis of the body and anæsthesia. Aphasia is very apt to coexist with the bulbar symptoms if the lesions involve the left insula, whose frontal folds are continuous with the speech-centre. Common hemiplegia with contracture, but without anæsthesia, represents a gross lesion of the kinesodic system, involving several cortical centres or the motor part of the internal capsule: (1) A widely-spread lesion of the cortex of the brain, softening of the motor zone (centres 1, 2, 3, 4) from embolism or thrombosis of the middle cerebral artery. (2) Hemorrhage from vessels of the nucleus caudatus and nucleus lentiformis compressing or destroying the motor segment of the internal capsule at various levels. More rarely there is a form of softening or gliomatous growth involving the same parts. Any of these lesions may be so localized as to destroy only one fasciculus of the capsule, giving rise to monoplegia. The limits of the so-called sensory and motor centres or cortical areas, and the possible localization of lesions in them, will be better understood by the help of the accompanying diagrams (Figs. 10 and 11, p. 90) of the lateral and mesal aspects of the hemisphere.