The son of Edward Wilson Duffin, MD (qv); was educated at King's College, London, and at the Universities of Edinburgh and Berlin. He came under the influence of Virchow in Berlin, and thus acquired an interest in pathology which coloured all his later work as clinician and teacher. He was House Physician at King's College Hospital in 1858 under Drs George Budd, Todd, and George Johnson. He became Assistant Physician there at the same time as Edward Liveing and Symes Thompson, but did not become Physician to in-patients until 1874. During the latter part of this long service in the out-patient room he devoted one afternoon a week to the treatment of out-patients with skin diseases, and his teaching in this subject was much appreciated by the students. In 1876 he succeeded Lionel Beale as Professor of Pathological Anatomy, and in 1893 was elected Professor of the Principles and Practice of Medicine. He held this latter chair alone for a few years, till joined in its duties by Burney Yeo, who succeeded him when he became Professor of Clinical Medicine. He was for a long period an active member of the Committee of Management of King's College Hospital. On retiring from service on the hospital staff in 1898 he was made Consulting Physician and Emeritus Professor of Medicine. From 1894-1896 he was a member of the Council of the Royal College of Physicians, and from 1889-1892 was an Examiner in Medicine. He also examined in medicine at the University of Edinburgh. He somewhat prided himself on being one of the few physicians practising medicine who possessed the qualification of FRCS. He was examiner for various Assurance Companies, and attended pretty regularly the meetings of the Pathological Society and the Clinical Society. For many years he was Physician to the Church Missionary Society, and was himself a man of strong religious convictions on Missions. He lived and practised for long at 18 Devonshire Street, Portland Place, W, and died, after his retirement, at his residence, Wallington, Surrey, on February 10th, 1913. He never married, but devoted his life to the companionship and care of an invalid relative. He left net personalty of over £48,000. Portraits of him accompany his biographies in the *Lancet* and *British Medical Journal*. Publications: "Cellular Pathology." - Beale's *Archives*, ii. "Perforation of Peritoneum." - *Ibid*. "Stricture of the Sigmoid Flexure: Colotomy." - *Trans. Pathol. Soc.*, 1868, xix, 197. "Temperature in Syphilis." - *Trans. Clin. Soc*., 1870, iii, 170. "Early Diagnosis of Small-pox." - *Ibid.*, 1871, iv, 117. "Treatment of Hydatids of the Liver." - *Ibid.*, 1878, vi, 23. "The Abstraction of Blood, Clinically Considered." - *King's College Hosp. Rep.*, 1895 i, 31. "Perinephric Abscess." - *Med. Times and Gaz.*, 1870, ii, 362.