Positive Characters.—Tendency to strictly hemiplegic or bilaterally hemiplegic grouping of symptoms; frequency of contracture or of a spastic state of the paretic muscles; increase of reflexes in the affected extremities; spasmodic manifestations in remote muscular groups, but not in areas of nerve-distribution (forms of Jacksonian epilepsy); the presence of paralytic and anæsthetic symptoms in the range of distribution of cranial nerves; frequency of neuro-retinitis or atrophy of the optic nerves; occurrence of lateral hemianopsia; production of symptom-groups known as varieties of crossed paralysis; frequency of head symptoms, as headache, vertigo, apoplectic and epileptic seizures; mental symptoms of various sorts, dementia, coma, etc. Negative Characters.—Absence of truly paraplegiform distribution of symptoms, even when they are bilateral; of cincture feelings; of pain or other paræsthesiæ and anæsthesia in the distribution of nerve-trunks; of muscular atrophy and De R. in paralyzed parts. Rarely do we observe visceral paralysis and bed-sores. Pathological localizations in the encephalon may conveniently be grouped under two heads—viz. systematic and focal lesions. A. SYSTEMATIC LESIONS OF THE ENCEPHALON.—The recent advances of embryology, anatomy, physiology, and pathological anatomy have conclusively established the existence, and fairly well defined the limits, of a sensory (æsthesodic) and of a motor (kinesodic) tract in the brain; and certain lesions of these tracts produce such precise symptom-groups that their diagnosis during the patient's life is often possible, and that, too, with great exactness.