Born in Dublin, the son of Dr William Barker. Studied medicine at the Medical School of the College of Surgeons, Dublin, and later at the University of Bonn, where he acquired a written and spoken knowledge of German as well as of French, which was of primary importance to him. Indeed, his first distinction came through his translation of the *Histologie und Histochemie des Menschen* by Professor Heinrich Frey, of Zurich. The work, first published in 1859, was illustrated by many woodcuts by Kölliker, much in advance of anything published before, and had been recommended to Barker by his teacher, Professor Max Schultze. The translation was published in 1874 and Barker’s preface is in a style characteristic of his subsequent writing. He was then living in Hume Street, Dublin, and was Surgeon to the City of Dublin Hospital, Demonstrator of Anatomy at the College of Surgeons, and Visiting Surgeon to the Convalescent Home at Stillorgan. Barker’s appointment at the age of 25 to the post of Assistant Surgeon at University College Hospital, London, in 1875, was out of the ordinary in that he had not passed the FRCS England, nor, indeed, did he qualify FRCSI, until the following year, 1876. Moreover, he received the FRCS England, in 1880 ad eundem. These occurrences have not repeated themselves. None the less, time, as it passed, showed Barker to be a leader of surgery in his day, fortified by his acquaintance with German surgery during its particularly flourishing period. University College Hospital was then the centre of Listerian surgery in London, from which Barker, following German surgeons (*see under* Bergmann, E von) began to deviate by using salicylic wool, perchloride of mercury, and adopting the so-called aseptic methods. The following is a selection in order of date from among Barker’s great surgical achievements during forty years: In 1880 he removed the kidney for a malignant tumour through an abdominal incision in a woman aged 21; the tumour had been noticed for eight months. The patient died of pulmonary embolism on the second day, after which it was found that the operation had been well performed, but there were secondary growths in the lungs the size of nuts. Barker referred in detail to Simon’s recently published monograph, including the record of twenty-eight cases, half of which had recovered and half had died. In clinical lectures in 1885 and 1889, he described further renal operations. In 1883 he rewrote articles in the third edition of the *System of Surgery* by Holmes and Hulke, on “Diseases of Joints”, “Diseases of the Spine”, and “Diseases of the Tongue”. In this last article there is a full account, with histological drawings, of leukoplakia, already recognized as a precursor of epithelioma. In 1886 he described four cases of removal of deep-seated tumours of the neck, which a few years before would have been held to be incurable. One case was probably an instance of an accessory thyroid, the others enlarged and tuberculous lymphatic glands. Also in 1886 he was the first to perform gastroenterostomy in London, and that successfully, for cancer of the pylorus in a woman aged 57, using the anterior method, the jejunum being turned over towards the right from its commencement. The patient survived for just over a year. In 1898 he noted that he had adopted von Hacker’s posterior gastrojejunostomy. In 1887 he published *A Short Manual of Surgical Operations*, illustrated by his own drawings, a capital résumé of the subject at that date. He was called upon at the hospital to examine and treat cases of ear disease before the institution of a special department, and this gave him opportunities for extending surgical measures beyond the opening of abscesses over the mastoid process after fluctuation had been detected. He had noted and explained anatomically the extension of suppuration from the middle ear to the temporomandibular joint. In four cases he trephined the mastoid antrum and drained the middle ear, so that in one case optic neuritis disappeared. In a case under Sir William R Gowers he first cleared out the disease from the middle ear and antrum, then trephined and drained a temporosphenoidal abscess. This appears to be the first case in which a cerebral abscess, due to tympanic suppuration, had been correctly diagnosed, localized, and then evacuated by operation, with complete success. Barker published a similar case in 1888, and his experience in this branch of surgery formed the subject of his Hunterian Lectures in 1889 on “Intracranial Inflammations Starting in the Temporal Bone”. To Barker is due the chief credit for establishing in this country the early diagnosis and immediate operation upon cases of intussusception. Previously there had been delay in making a definite diagnosis, and attempts at reduction by distending with water the bowel below the intussusception were generally disastrous failures. Barker saw the patient, a boy aged 4, twelve hours after the onset of the symptoms. He first distended the bowel with water until the tumour became imperceptible; five hours later he operated, reduced the intussusception, and the boy recovered. The table of cases showed how unsuccessful had been laparotomy done late in the case. He also operated successfully on the other variety of intussusception, that caused by a new growth in the rectum. Further reports on intussusception were published in 1894, 1897, and 1903 – the last in German. On the subject of active surgical interference with tuberculous disease of the hip- and knee-joint at an early stage Barker was led into error by following German authorities. In evidence of this, note the list at the end of his third Hunterian Lecture in 1888. He was quite right in substituting the term ‘tuberculous’ in place of the indefinite ‘strumous’ used, e.g., by Howard Marsh (qv) in his *Diseases of Joints*, 1886; but the getting rid of a disease which, however it had got there, had become completely localized in the joint, by removing the interior of the joint at a surgical operation, was an erroneous assumption. Howard Marsh stated the experience gained at the Alexandra Hospital for Hip Disease in favour of prolonged rest under good conditions, together with any surgical measures as restricted as possible. There followed increased support of Marsh’s contention, and great advances have occurred in combination with fresh air and sunlight. In 1887 Barker described thirty-five cases in which he had undertaken the radical cure of hernia, just at the time when that operation was coming into general use. He introduced improvement, including the removal of the neck of the hernial sac at its junction with the peritoneum. By 1898 he had operated upon 200 cases with three deaths. He had modified his earlier procedure to that of Bassini’s “as the best operation of any yet devised”. He used hard twisted Chinese silk, boiled in 5 per cent of carbolic acid; in 21 of the 200 there were reports that silk knots had worked out. In 1892, and again in 1896, he described his method of applying a ‘subcutaneous suture’ to bring together a recent fracture of the patella. His second report confirmed his primary experience, but in other hands and even in the earliest cases it proved difficult to get the fractured surfaces into apposition with none of the aponeurosis intervening. Hence with increasing certainty as to asepsis, the open operation continued the standard method. He published in 1895 two cases illustrating obliteration of psoas abscesses after one washing out, scraping, and closure without drainage. His flushing spoon was adopted as most useful and convenient, the actual scraping of the inside of a psoas abscess being practically omitted. The closure without drainage had the advantage over that of Lister’s success in draining, that there was no chance of secondary infection through the drainage tube. Barker gave great attention to detail in the designing of instruments and apparatus, and in carrying out exact asepsis, as well as in the use of local anaesthesia. In 1898 he published the description of the ‘sewing machine needle’ for the introduction of sutures whether intestinal or cutaneous. A reel of silk, after sterilization by boiling, was fixed on the handle of the instrument, so that the reel could be turned to pay out or wind up the thread by the thumb. The needle was held at right angles to the handle, threaded from the reel. It could thus be used for passing interrupted sutures, by cutting the thread beyond the needle. Strictly speaking it lacked the sewing-machine shuttle carrying the under thread and moving at the same time as the needle armed with the upper thread. Barker passed the needle well through, drew it back a little to form a loop, and then with his left thumb and finger passed the free end of the thread through the loop – to make a continuous looped stitch. Practice with both hands was necessary, and also practise in regulating the tightness of the stitch. In describing his sewing-machine needed he noted silk as the thread, but in 1902 he adopted linen sewing-machine thread for ligatures and sutures. In 1899 Barker gave a “Clinical Lecture and Demonstration on Local Analgesia” “which has of late been practised in many parts of the world”, using 1-1000 eucain ß in normal saline solution. He continued in subsequent years to make reports of improvements in technique. In 1907 he published a full description of spinal analgesia in 100 cases by injecting stovaine. In the following year a further series exhibited improvement by the addition of 5 per cent glucose to increase the density and limit the spread of the fluid. The Obituary Notice in the *British Journal of Surgery* said: “The profession in this country is deeply indebted to him for the share which he took in promoting the subject, and for recording his work with sufficient detail to enable others to practise the method with a great measure of success”. Of all the Clinical Lectures which Barker published none was better, and bears re-reading with greater advantage, than that delivered in 1906, entitled, “The Hands of Surgeons and Assistants in Operations”. The title does not cover all the ground. He commenced: “We have now arrived at an era in which we may claim to know a great deal about septic processes”, and he proceeded to summarize half a dozen possible avenues of infection where operations are undertaken: access from the patient’s own body; access from without, from his skin, from the atmosphere, from the instruments employed in making the wound and in its treatment, ligatures, swabs and dressings, and in addition to the “Hands of Surgeons and Assistants, their Clothes and Breath”. No surgeon spent more of his time and his attention over the technique of the surgeon. In the Address on Surgery at the Belfast Meeting of the British Medical Association in 1909, he reviewed in particular the advances made in intestinal surgery in which he had taken such a great part, including a definition of the protective power of the peritoneum, the faculty possessed by the intestinal coats in health of preventing migration of micro-organisms and the loss of this faculty as a consequence of disease and accident, the wider choice of anaesthetics, the success in removing malignant disease of the colon. In 1914, in apparently his last communication, he returned to the subject of leukoplakia which he had described so ably forty-one years before in the Holmes and Hulke *Surgery*. A charming and witty conversationalist, Barker was not a lively speaker. As a teacher he was at his best when discussing and explaining some subject in which at the time he was particularly interested. When lecturing he was apt to deal in allusions and to get above the level of his hearers. He examined at the Universities of London and Manchester, but he seemed to find it difficult to maintain rigorously his attention upon an exacting task. He had acted as Consulting Surgeon to the Queen Alexandra Hospital, Millbank, and to the Obsborn Convalescent Home for Officers. At the outbreak of the War he served as Colonel AMS, at Netley, next at Malta, and then at Salonika. He died there of pneumonia on April 8th, 1916. He practised at 144 Harley Street. A portrait appears in the *British Journal of Surgery*. By his marriage in 1880 to Emilie Blanche, daughter of Mr Julius Delmege, of Rathkeale, Co Limerick, he had issue two sons and four daughters. In the midst of all his work he had great anxiety even during the last days of his life. The younger son died of acute ear disease. The elder, after entering the Army, developed signs of chronic bilateral pulmonary tuberculosis, for which he was invalided. He rejoined six weeks before the outbreak of War, was wounded and taken prisoner. During this time the tuberculosis again became active. On his release after his father’s death the disease was held in check until an attack of bronchopneumonia proved fatal. Publications:- *The Histology and Histo-chemistry of Man*, by Heinrich Frey, translated from the 4th German edition by A E J Baker, 1874. “Nephrectomy by Abdominal Section” – *Med.-Chir. Trans.*, 1880, lxiii, 181; also “Clinical Lectures Illustrating cases of Renal Surgery.” – Lancet, 1885, i, 93, 141; 1889, i, 418, 466. Holmes and Hulke, *System of Surgery*, 3rd ed, 1883, ii. “On the Removal of Deepseated Tumours of the Neck.” – *Lancet*, 1886, i, 194. “A Case of Gastro-enterostomy for Cancer of the Pylorus and Stomach.” – *Brit. Med. Jour.*, 1886, i, 292, 618; also *The Surgical Affections of the Stomach and their Treatment*, 1898. *A Short Manual of Surgical Operations*, 1887. Erichsen and Beck, *Science and Art of Surgery*, 8th ed. 1884, ii, 600. Gowers and Barker, *Brit. Med. Jour.*, 1886, ii, 1154; 1888, i, 777. “Hunterian Lectures on Intracranial Inflammation Starting in the Temporal Bone, their Complications and Treatment.” – *Illust. Med. News*, London, 1889, iv, 10, 35, 63, 82, 108. “A Case of Intussusception of the Caecum, Treated by Abdominal Section with Success.” –*Lancet*, 1888, ii, 201, 262. “A Case of Intussusception of the Upper End of the Rectum due to Obstruction by a New Growth. Excision with Suture. Recovery.” – *Med.-Chir. Trans.*, 1887, lxx, 335. “Cases of Acute Intussusception in Children.” – *Brit. Med. Jour*., 1894 , i, 345. “Fifteen Consecutive Cases of Acute Intussusception with Appendix of all Cases at University College Hospital.” – *Trans. Clin. Soc. Lond*., 1897-8, xxxi, 58. “Zur Casuistik des Darm-Invagination.” – *Arch. f. klin. Chir*., 1903, lxxi, 147. “Three Lectures on Tubercular Joint Disease and its Treatment by Operation.” – *Lancet*, 1888, i, 1202, 1259, 1322. “Diseases of Joints” in Treves’ *System of Surgery*, 1896. “Operation for the Cure of Non-strangulated Hernia.” – *Brit. Med. Jour.*, 1887, ii, 1203; 1890, i, 840; 1898, ii, 712. “Permanent Subcutaneous Suture of the Patella for Recent Fracture.” – *Brit. Med. Jour.*, 1892, i, 425; 1896, i, 963. “Two Cases Illustrating Obliteration of Psoas Abscesses after one Washing out and Scraping and Closure without Drainage.” – *Trans. Clin. Soc.*, 1895, xxviii, 301. “Sewing Machine Needle.” – *Brit. Med. Jour.*, 1898, ii, 148. “A Short Note on the Use of Linen Sewing Machine Thread for Ligatures and Sutures.” –*Lancet*, 1902, i, 1465. “Clinical Lecture and Demonstration on Local Analgesia.” – *Lancet*, 1899, i, 282; 1900, i, 156; 1903, ii, 203. “A Report on Clinical Experiences with Spinal Analgesia.” – *Brit. Med. Jour.*, 1907, i, 665; 1908, i, 244. “Clinical Lecture on the Hands of Surgeons and Assistants at Operations.” – *Lancet*, 1906, i, 345. “Progress in Intestinal Surgery.” – Address on Surgery at the Belfast Meeting of the British Medical Association. – *Brit. Med. Jour*., 1909, ii, 263. “Leukoplakia.” – *Practitioner*, 1914, xciii, 176.