Description: Segment 1 The symptoms of Ataxia in a young girl are seen. Intertitle: 'This is a rare chronic disease hereditary and familial, with onset usually early in life and progressing to complete disability'. Intertitle (partly obscured): 'The posterior columns, the anterior and posterior spino-cerebellar tracts. The pyramidal tracts below the medulla'. Diagram of cross section of the spine. Intertitle: 'The typical symptoms are unsteadiness of gait, ataxia of arms, and jerky indistinct speech. This girl is ten years old'. Shots of girl walking in room, showing unsteadiness and some difficulty drinking from a glass of water. Intertitle: 'Nystagmus is just detectable'. Shot of a girl having her eyesight examined, slight saccadic movement. Shot of a girl touching her nose and the doctors hand, with a small amount of difficulty. Intertile: 'The ataxia and the incoordination are due to lesions of the spino-cerebellar tracts'. Shots of the girl moving her limbs in uncoordinated fashion. Intertitle: 'Exaggerated knee jerks are due to pyramidal tract lesions. Ankle jerks are absent. This is probably due to damage of the short fibres of the reflex arc which passes through the posterior columns'. Shots of the girl having her reflexes tested. The more advanced symptoms in the girl s older brother are seen. Intertitle: 'The girl's brother is now 25 years old, symptoms first appeared at the age of six.' Shots of a young man walking with an abnormal gait showing much difficulty in drinking glass of water a close shot of his eyes shows saccadic movement. He displays difficulty in undertaking finger nose coordination and in shaking hands rhythmically. Intertitle: 'In this more advanced case pes cavus and hammer toes may be observed'. Close shot of the subject s foot, shots of reflexes being tested. Intertitle: 'These cases showed little evidence of posterior column degeneration'. Time start: 00:00:00:00 Time end: 00:05:43:24 Length:00:05:43:24.