The third son of John Mayo (1761-1818), MD Oxon, born in Queen Anne Street, London, on April 3rd, 1796. He entered the Middlesex Hospital on May 17th, 1814, and was there a pupil of Sir Charles Bell until 1815, becoming a House Surgeon in 1818, by which time he had taken his MD degree at Leyden. In 1826 he purchased, with Cesar Hawkins, Sir Charles Bell's interest in the Hunterian or Great Windmill Street School of Medicine, and carried it on with the assistance of George Gisborne Babington (qv) until 1830. The school declined steadily in numbers, and Mayo endeavoured to sell it as a going concern to Dr J A Wilson and Samuel Lane (qv). The negotiations fell through, and Lane started a private school of medicine adjoining St George's Hospital in 1831. The relationship of the two schools remained friendly, and some of the pupils from Windmill Street were transferred to Lane's School with the remark that "they will not lose by the change, but will find the school at St George's a genuine artery of the old Windmill Street stock." Mayo was elected Surgeon to the Middlesex Hospital in 1827, and resigned his post in 1842. From 1828-1830, in succession to J H Green (qv), he was Professor of Comparative Anatomy at the Royal College of Surgeons, delivering fifteen lectures yearly. He was appointed Professor of Anatomy at King's College when the school was established in 1830, and became Professor of Physiology and Pathological Anatomy there in 1836. He applied unsuccessfully for a vacant professorship at University College, resigned his chair at King's College, and devoted himself from 1836 to the establishment of a medical school at the Middlesex Hospital. His health began to fail in 1843 owing to osteo-arthritis, and he became so crippled that he resigned his appointments and became physician to a hydropathic establishment, first at Boppart and afterwards at Bad Weilbach, where he died on May 15th, 1852. He married Jessica Matilda, daughter of Samuel James Arnold (1774-1852), the dramatist, by whom he had one son and two daughters. Mayo early became involved in the question of priority in the discovery of the function of the trigeminal and facial nerves which was claimed for Sir Charles Bell, the truth appearing to be that whilst Bell showed roughly that the facial nerve was motor and the fifth sensory, the demonstration was elaborated and proved by Mayo and Magendie. There is no doubt that Mayo was the true father of the Middlesex Hospital Medical School in 1836, although the appointment of Charles Bell as Surgeon in 1812 had greatly enhanced the reputation of the Hospital. In later life Mayo was somewhat of a mystic and became interested in mesmerism and its phenomena. The College Collection contains a mezzotint of Mayo at about 40 years of age, engraved by David Lucas from a painting by J Lonsdale; also a lithograph by T Bridgford representing him later in life. Publications:- *Anatomical and Physiological Commentaries*, Part 1, August, 1822. It contains an account of his experiments to prove the function of the portio dura. Part 2 was published in July, 1823. *Outlines of Human Physiology*, 8vo, London, 1827 ; 2nd ed, 1829. *Outlines of Human Pathology*, 8vo, London, 1836. Translated into German, Darmstadt, 1838-9. *The Cold Water Cure*, 1845. *Letters on Truths in Popular Superstitions*, 8vo, London, 1848 and 1851.