(b. London, England, 3 May 1796; d. Bad Weilbach, Germany, 15 May 1852)
Herbert was the third son of John Mayo; his father and his eldest brother, Thomas, were prominent physicians in London. He was a pupil of Charles Bell at the Windmill Street Anatomy School (1812–1815) and graduated M.D. at Leiden in 1818. He was admitted a member of the Royal College of Surgeons by examination in 1819 and elected among the first fellows in 1843. He practiced surgery and taught anatomy in London from 1819 to 1843, becoming senior surgeon to the Middlesex Hospital, where he founded the Medical School in 1836; he also wrote many successful textbooks.
Charles Bell had circulated privately in 1811 his Idea of a New Anatomy of the Brain, which showed that the anterior roots of the nerves atone have motor functions; ten years later, in 1821 Bell contributed to the Philosophical Transactions a paper “On the Nerves; Giving an Account of Some Experiments on Their Structure and Functions, Which Lead to a New Arrangement of the System.” Bell here put forward the concept of the motor function of the anterior and the sensory function of the posterior roots, but as Claude Bernard later wrote, “drowned in philosophical considerations so obscure or diffuse that it is difficult to find places where his opinions are succinctly stated.”
Mayo announced his independent discoveries of the physiology of the nerves in his Anatomical and Physiological Commentaries; the first part (August 1822) included a paper which described “Experiments to Determine the Influence of the Portio Dura of the Seventh and the Facial Branches of the Fifth Pair of Nerves” part two (July 1823) opened with a paper “On the Cerebral Nerves With Reference to Sensation and Voluntary Motion,” and it concluded with “Remarks Upon the Spinal Chord and the Nervous System Generally,” Mayo attributed sensibility to the fifth nerve and motor power to the seventh nerve, and he showed that a circumscribed segment of the nervous system sufficed to produce muscular action. He wrote that “An influence may be propagated from the sentient nerves of a part to their correspondent nerves of motion through the intervention of that part alone of the nervous system to which they are mutually attached” the term “reflex” was applied to this phenomenon by Marshall Hall in 1833. Neither Bell nor Mayo seems to have known at this time that François Magendie had achieved similar results in research which was reported in Paris (1821–1823). Bell protested his claim to priority against both Mayo and Magendie.
Mayo supplemented the fifteen plates in his Commentaries by an atlas of six larger plates (each plate was printed in an outline and a shaded version) entitled A Series of Engravings Intended to Illustrate the Structure of the Brain and Spinal Chord (1827). The brief text is pure descriptive anatomy, except for a paragraph (p. iii) in which Mayo stated,
The filaments of which the nerves consist have the office of conductors. We may therefore infer that die white threads which enter so largely into the composition of the spinal marrow, the medulla oblongata, and the brain, likewise serve as media for conveying impressions. The justice of this conclusion in the instance of the spinal marrow has been proved by experiments made on animals.
He added that his observations would prove useful for pathologists in explaining “interruption or impairment of functions.”
Although he made no further original discoveries, Mayo retained his interest in neurology. In his Outlines of Human Physiology (3rd ed., 1833, p. 219) he gave “an extension of the original law respecting the place of origin of the nerves.” He published a pamphlet on the Powers of the Roots of the Nerves in 1837 in reply to R. D. Grainger’s Observations on the Structure and Function of the Spinal Cord; Mayo described this as a restatement of his views after conversations with Grainger. In an appendix he discussed recent demonstrations of hypnotism, “magnetic sleep.” by Baron Dupotet and concluded that “persons susceptible of it may be thrown into a kind of trance by the influence of imagination excited through the senses.” He also anticipated a possible value for anesthetizing a patient before “a surgical operation of little severity.” In the main pamphlet Mayo also stated: “Nerves, it was discovered by the independent researches of Sir C. Bell, M. Magendie, and myself (each having contributed his separate share to the result) are of two kinds only, one sentient, the other voluntary.” He did not discuss Bell’s claims, but recorded (p. 8) the highest regard for Magendie’s results and integrity, and he mentioned (p. 20) that “Dr Marshall Hall, who invented the term ’reflex action,’ has followed out the idea with great diligence, showing fresh instances parallel to my own, which I reduced to one theory in 1823.”
Mayo’s final work on the subject was his monograph The Nervous System (1842). This was begun as a physiological introduction for a reissue of the 1827 Engravings, but in the event the illustrations were not reprinted. Mayo wrote that his new “survey of the nervous system and the reflections to which it gave rise did not elicit much that is new, yet display what has been discovered with new distinctness and force.”
Mayo retired to Germany in 1843 for hydropathic treatment as a victim of “rheumatic gout,” and while there he wrote on The Cold Water Cure and on Mesmerism. He died in Germany at the age of fifty-six, survived by his wife, a son, and two daughters.
I. Original Works. His writings on neurology are Anatomical and Physiological Commentaries, pt. 1 (August 1822), pt. 2 (July 1823); A Series of Engravings Intended to Illustrate the Structure of the Brain and Spinal Chord in Man (1827); Powers of the Roots of the Nerves in Health and Disease, Likewise On Magnetic Sleep (1837); and The Nervous System and Its Functions (1842).
Textbooks which Mayo wrote include A Course of Dissections for Students (1825); Outlines of Human Physiology (1827, 1829, 1833, 1837); Observations on Injuries and Diseases of the Rectum (1833; Washington, 1834); Outlines of Human Pathology (1836; Philadelphia, 1839; 1841), trans. into German (1838–1839); The Philosophy of Living (1837, 1838, 1851); Management of the Organs of Digestion in Health and Disease (1837, 1840); A Treatise on Siphilis (1840), trans. into German (1841); The Cold Water Cure (1845); and Letters on the Truths in Popular Superstitions With an Account of Mesmerism (Frankfurt, 1849), 2nd and 3rd eds. (Edinburgh, 1851).
II. Secondary Literature. Biographical memoirs of Mayo are in the Dictionary of National Biography, XXXVII (1894); D’A. Power, ed., Plarr’s Lives of the Fellows of the Royal College of Surgeons (1930); and John F. Fulton, Selected Readings in the History of Physiology, 2nd ed., Leonard G. Wilson, ed. (1966), 285–286.