The younger son of Major Cotes, RA. He was educated at St Paul's School and at Gonville and Caius College, Cambridge, being appointed, before graduation in medicine and surgery, Assistant Demonstrator of Anatomy in the University Medical School. Returning to St George's Hospital, where he had already done work during one year, he filled several minor posts and became House Surgeon in 1884, Anaesthetist in 1887, Surgical Registrar in 1889, and Demonstrator of Anatomy in 1891. It was at this time that he began to exhibit his remarkable abilities as a teacher, and six generations of students at St George's Hospital can testify to the practical value of his demonstrations in surgery. In 1888 he was appointed Surgeon to the Great Northern Hospital and to the Well Street Branch of the Seamen's Hospital, and was elected Surgeon to Out-patients at the Lock Hospital in 1889. Here he had opportunities for observing venereal disease so extensive that he wrote a dogmatic paper on a "New Treatment of Gonorrhoea," in which he advocated drastic treatment in the early stages. This was only one of several original contributions to surgery. In 1890 he developed symptoms of phthisis and resigned some of his hospital posts, but he was still Demonstrator of Anatomy, with large clinical classes in surgery, heavy work at the Lock Hospital, and a rapidly growing private practice. He took a trip to Australia in 1891 and returned with his trouble apparently arrested, but he broke down completely in the autumn of 1892. He intended to live out of England with his young wife for the sake of his health, but died at Bournemouth on May 4th, 1893, without being able to realize his wish. His London address was latterly 42 Davies Street, Berkeley Square.