Was a student at St Bartholomew’s Hospital, where he won many honours and prizes, including the Lawrence Scholarship and Gold Medal. He held for some years the post of House Surgeon at Tunbridge Wells Infirmary. In 1848 he became the Resident Apothecary at Westminster Hospital, combining in an elementary and general way the duties now performed by a Dispenser, House Physician, and Resident Medical Officer. The physician then attended only once or twice a week unless specially summoned, and those who were acutely ill came under the care of the apothecary, who visited the wards and prescribed. Hence, there was sometimes trouble with the physicians. Barlow’s attention was attracted to the movements occurring in patients dying from cholera, yellow fever, etc. – namely, the opening and closure of the lower jaw, continuing rhythmically for two hours, as in animals after decapitation, co-ordinated muscular movements displacing a limb, or tremulous movements and spasmodic twitches of muscles of the abdominal wall and the sartorius – rigor mortis supervening but slowly. He also noted a similar muscular movement in a case dying of apoplexy, continuing for three-quarters of an hour – all subjects of medico-legal interest. His essays on “Volition” extended Hunter’s observation, and followed upon Marshall Hall’s demonstration of the spinal reflexes; moreover he anticipated in some degree conditional reflexes. He further noted, as has often been done since, the muscular movements occurring during artificial respiration, and the increased excitability of muscles if touched. Indeed, his essays are a mine of vague clinical observations anticipating subsequent advances in the physiology and pathology of the nervous system. Whether from friction between him and the physicians at Westminster Hospital, or from overwork, he had only just passed the FRCS examination on June 22nd when he exhibited signs of mental excitement. This passed on to an acute intracranial affection, from which he died on June 24th, 1853, at his father’s house at Writtle, near Chelmsford. He was unmarried. Publications:- *Essay on the Relation of Volition to the Physiology and Pathology of the Spinal Cord*, 1848. *Essay on Volition as an Exciter and Modifier of the Respiratory Movements*, 1849. *On the Muscular Contractions Occasionally Observed After Death from Cholera*, 2 parts, 1849-50, and Supplement, 1860. *Observations on the Condition of the Body after Death from Cholera*, 1850. *Case of Softening of the Brain, with General Observations on Fatty Degeneration*, 1853. *On the Atrophy of Paralysis*, 1853.