Born at 50 Camberwell Road, SE, on 25 April 1882, the eldest son of J Walter Perrin, a City merchant, and Harriet S Savage, his wife. He was educated at Wilson School under Mr McDowell, at Richmond Hill School under Mr Whitbread, and at the City of London School under Mr A T Pollard. On 1 October 1901 he was admitted with a Tancred scholarship to Gonville and Caius College, Cambridge. He graduated BA in 1904, after gaining a first class in Part 1 of the Natural Sciences Tripos and a first class in zoology in Part 2. He had by this time come under the influence of Adam Sedgwick of Trinity College, who was starting a school of protozoology at Cambridge. Perrin was given the Shuttleworth research scholarship and the Thruston prize by Caius College and was sent to Austria, where he went to the zoological station at Rovigno, Istria, and worked in the laboratory of Prowazek during the autumn of 1904 and the first half of the year 1905. On his return to England he was awarded the Walsingham medal and £20 given by the University of Cambridge for papers published as a result of his work on protozoology with Prowazek, and was given the post of University demonstrator of zoology under Sedgwick. He remained in Cambridge trying unsuccessfully for a Fellowship at Caius College and maintaining himself by coaching until 1907, when he realized that zoology would not maintain him and turned to medicine. He entered the London Hospital as a student, gained an entrance scholarship and two years later the Jonathan Hutchinson prize for an essay on intussusception, was awarded the medical and surgical scholarships, and was admitted MRCS and LRCP in 1912. He took the Mastership of Surgery at Cambridge in 1914, but never graduated MB. At the London Hospital he filled the posts of house surgeon, house physician, and surgical registrar, was elected assistant surgeon in 1921, and became surgeon in 1928. He also acted in the medical school of the hospital as demonstrator of anatomy when William Wright was head of the department. During the war Perrin acted first as officer in charge of the Belgian Field Hospital at Fumes; he was gazetted temporary lieutenant, RAMC on 12 March 1918 and temporary captain a year later, on appointment as a surgical specialist at various casualty clearing stations in France. On demobilization he returned to his ordinary civil duties. He married Dorothy Edith Rafferty on 9 December 1916; she survived him with two sons and a daughter. He died after a short illness on 8 December 1935 at 16 Upper Wimpole Street, aged 53. Perrin, had his means allowed of it or had he gained a properly remunerated teaching post, would have been as good a protozoologist as he afterwards became a surgeon. He was excellent at research and a trained teacher of students. As a surgeon he devoted himself more especially to the diseases of the rectum, and was president of the subsection of proctology at the Royal Society of Medicine in 1932-33. His last appointment was as surgeon to the Royal Masonic Hospital. Publications: A preliminary communication of the life history of Trypanosoma balbianii. *Proc Roy Soc* 1905, B 75, 368. Researches upon the life history of Trypanosoma balbianii. *Arch Protistenk* 1906, 7, 131. Preliminary communication on the life history of Pleistophora periplanetae. *Proc Camb Phil Soc* 1906, 13, 204. Observations on the structure and life history of Pleistophora periplanetae. *Quart J micr Sci* 1905-06, 49, 615. Note on the possible transmission of sarcocystis by the blowfly. *Spolia Zeylan* 1907, 4, 58. Intussusception, a monograph based on 400 cases, with E C Lindsay. *Brit J Surg* 1921-22,9, 46-71. The ambulatory treatment of piles. *Lancet*, 1929, 1, 569.