the College of Physicians. About 1762 he returned to London and soon obtained an extensive practice as an accoucheur. He was physician to the Princess Dowager of Wales, fellow of the Royal Societies of London and Göttingen, and a vice-president of the British Lying-in Hospital, of which he had been one of the founders. On 20 June 1792 he had the honorary degree of D.C.L. conferred upon him at Oxford (Foster, Alumni Oxon. 1715-1886, iii. 827). He died at Greenwich in February 1802 (Gent. Mag. vol. lxxii. pt. i. p. 281). His son, Charles Peter Layard (1748-1808), successively prebendary of Bangor, prebendary of Worcester (1793), and dean of Bristol (1800), was grandfather of Sir Austen Henry Layard.
Layard contributed some papers to the 'Philosophical Transactions,' and published: 1. 'An Essay on the Nature, Causes, and Cure of the Contagious Distemper among the Horned Cattle in these Kingdoms,' 8vo, London, 1757. 2. 'An Essay on the Bite of a Mad Dog,' 8vo, London, 1762. 3. 'An Account of the Somersham Water in the County of Huntingdon,' 8vo, London, 1767. 4. 'Pharmacopœia in usum Gravidarum Puerperarum,' &c., 8vo, London, 1776.
[Munk's Coll. of Phys. 1878, ii. 181-2.]
LAYCOCK, THOMAS (1812–1876), mental physiologist, born at Wetherby in the West Kiding of Yorkshire in 1812, was educated at the Wesleyan academy, Woodhouse Grove, and at University College, London. He studied anatomy and physiology under Lisfranc and Velpeau at Paris during 1834, became M.R.C.S. in 1835, contributed in 1837 a valuable paper on 'The Acid and Alkaline Reactions of the Saliva' to the 'London Medical Gazette.' and graduated M.D. at Gottingen, 'summa cum laude.' in 1839. Laycock had already begun to specialise upon the relations existing between the nervous system and various psychological phenomena. His leisure he devoted to the perusal of the Cambridge platonists, especially Ralph Cudworth [q. v.] In 1840 appeared his first separate work, 'A Treatise on the Nervous Diseases of Women, comprising an Inquiry into the Nature, Causes, and Treatment of Spinal and Hysterical Disorders.' Like his later works it is highly concentrated, and embodies the results ofmuch profound observation. It procured for the author the acquaintance of sir John Forbes, editor of the 'British and Foreign Medical and Chirurgical Review.' to which Laycock became henceforward a constant contributor. In the following year, in a series of letters in the 'Dublin Medical Gazette.' he sketched a complete plan of political medicine, now known as state medicine, which was generally regarded as authoritative.
Laycock was the first to formulate, in a paper before the British Association at York in 1844, the theory of the reflex action of the brain, which has since been developed by Carpenter and others. In the same year he was elected secretary of the British Association. In 1846 he was appointed lecturer on clinical medicine at the York School of Medicine. Here in 1851 he translated and edited for the Sydenham Society J. A. Unger's 'Principles of Physiology.' and 'A Dissertation on the Functions of the Nervous System.' by the great Austrian physiologist, G. Prochaska. Towards the close of 1855 he was, after a severe contest, elected professor of the practice of physic in Edinburgh University, as successor to Dr. W. Pulteney Alison [q. v.] He is the only Englishman who has occupied that chair. At Edinburgh in 1859 he published his important work, 'Mind and Brain, or the Correlations of Consciousness and Organisation, with their Applications to Philosophy, Physiology, Mental Pathology, and the Practice of Medicine.' 2 vols. 8vo; 2nd edit. 1869. Here Laycock first systematically advanced the hypothesis that there are vascular regions of the brain corresponding to certain functional localisations, which has since been confirmed by the researches of Hubner and Duret. It prepared the way for the study of unconscious cerebration, to which Laycock henceforth chiefly devoted himself. His last papers on the subject appeared in the 'Journal of Mental Science' for January and April 1876. He died at his house, 13 Walker Street, Edinburgh, on 21 Sept. 1876. He was elected a F.R.S. Edinburgh in 1861. Altogether absorbed in his researches, Laycock was in manner dry, cold, and frequently abstracted. His faculty for original observation was greater than nis powers of reasoning, and he was unable to embody his results in an attractive form. But he was the first to apply the theory of evolution to the development of the nervous centres in the animal kingdom and in man.
Laycock was author of some three hundred articles in medical journals. He published, besides the books already noticed: 1. 'Lectures on the Principles and Methods of Medical Observation and Research.' Edinburgh, 1856, 8vo; 2nd edit., with copious nosologies and indexes of fevers, &c., Edinburgh, 1884, 8vo. 2. 'The Social and Political Relations of Drunkenness.' Two Lectures, Edinburgh, 1857, 8vo. Reprinted in the same year at Hobart Town, Tasmania.