Born in June, 1830, at Clifton, his father being a member of an old Scotch family, his mother of a family many of whom belonged to the medical profession. He was educated at Bishop’s College, Bristol, and entered St Bartholomew’s Hospital in 1849. He was in due order Dresser, Clinical Clerk, House Surgeon, Registrar, Assistant Surgeon, and Surgeon in 1871; in the Medical School he was Demonstrator of Morbid Anatomy and of Anatomy, Lecturer on Comparative Anatomy, and in 1873 Lecturer on Surgery. In 1873 he was Professor of Anatomy at the Royal College of Surgeons. Among other posts he was Examiner in Anatomy and in Surgery at the University of London, also President of the Clinical Society. The papers communicated to the Royal Society show that, though practical surgery was the main object of his professional life, he never gave up the love of anatomy which he acquired in his student days. The subjects which he chose for investigation may indicate the difficulties on which he was prepared to work, and he justified himself by success. His paper in the *Philosophical Transactions* on “The Formation and Growth of the Bones of the Human Face” was praised by Sir James Paget, and, added to his other merits, ensured his election to the Fellowship of the Royal Society in 1871. Of the paper on the “Axial Arches” the same good judge writes: “It was very important, but only treated of one or two stages; if he had gone on with the research it would have been a work of great price. The same may be said of what he did in the study of ‘The Formation and Early Growth of the Brain of Man’. This was the subject of his Lectures as Professor of Anatomy at the College in 1873.” Concerning his surgery when major surgery was limited to excisions and amputations, trephining and lithotomy, Lister’s methods had no general acceptance. There was no abdominal surgery but for hernia, and that was limited to relief by incision of the constriction. “His operations were dexterous and neat, and all preparations for them were trim, in due place and time…. All was scrupulously watched over by himself; he seemed never tired of taking care for the cleanliness and comfort of his patients.” In his essay on the “Anatomy of the Parts concerned in Femoral Rupture” (London, 1863) the notes concerning the descriptions of each structure by the earlier anatomist are longer than the text itself. “In dividing these structures for the relief of strangulated intestine, the incisions should be as small as possible” (p. 50). Then there was no question of suture, so that the result of herniotomy was an enlarged aperture. In his address delivered to the students at St Bartholomew’s Hospital on October 3rd, 1864 (published under this title in London in the same year), he specially emphasized the study of pathological anatomy, but the microscope is not mentioned. In his essay “On the Present System of Medical Education in England” (London, 1864) he observed: “It is my opinion that little, if any, change in the existing regulations is at present desirable”, and the final paragraph began with, “This I would add. At St Bartholomew’s we have always held back from the introduction of what may be termed extra courses of lectures, and we may, I think, congratulate ourselves on having done so. Skin diseases, ear diseases, and so forth, can be learnt for all practical purposes without the aid of special instructors.” Callender’s last publication was his address at the opening of the Section of Surgery at the Bath Meeting of the British Medical Association. The subject was “The Avoidance of Pain”, in which he mentioned a great variety of causes and their relief, but neither sepsis nor antisepsis, nor Lister’s procedure. Neither the words nor any implication of such methods finds mention except the use of carbolic oil. The preface to his remarks was, however, printed in italics: “An operation or an accident wound can be so treated that the patient from the first to last shall be free from pain; and in the treatment of many other troubles a great deal of pain may be avoided by forethought and care on the part of the surgeon.” The first part of the sentence implied the free use of opium. In person Callender was a tall, powerfully built man with a remarkably low forehead. He was extremely fond of horses, and on more than one occasion drove a coach and four into the Hospital Square. He had become the subject of Bright’s disease, and in September, 1878, went on a voyage to the United States, where he became worse. He died on October 20th at sea on the return voyage. He practised in Queen Anne Street, was married, and had a son and two daughters. He was buried at Kensal Green Cemetery. Publications: “The Formation and Early Growth of the Bones of the Human Face.” – *Phil. Trans.*, 1870, clix, 163. “Removal of a Needle from the Heart; Recovery of the Patient,” London, 1873; reprinted from *Med.-Chir. Trans*. “Anatomy of the Thyroid Gland.” – Abstract, *Proc. Roy. Soc.*, 1867-8, xvi, 24, 183. “The Formation of some of the Subaxial Arches of Man.” – *Ibid.*, 1870-1, xix, 380. Several articles – “Pyæmia,” “Injuries and Diseases of Veins” – in Holmes’s *System of Surgery*, 2nd ed., London, 1870. “The Avoidance of Pain.” – *Brit. Med. Jour.*, 1878, ii, 213. “Lectures on Clinical Precision,” London, 1876.