SIR JOHN LEDINGHAM, emeritus professor of bacteriology in the University of London and a former director of the Lister Institute of Preventive Medicine, died in London on October 4 after a brief illness. John Charles Grant Ledingham—'a son of the manse'—was born in 1875, his father, the Rev. John Ledingham, being the minister of Boyndie, Banffshire. He was educated at Boyndie Public School, Banff Academy, and the University of Aberdeen, where he achieved many successes including the Simpson and Arnott Prizes and the Anderson Scholarship. He graduated with first-class honours in mathematics and physics, obtaining the B.Sc. degree with distinction. After a brilliant career in the Faculty of Medicine he obtained the M.B. degree with honours in 1902. Postgraduate study at the University of Leipzig and at the London Hospital followed, and in 1905 he joined the staff of the Lister Institute, being appointed assistant bacteriologist at Elstree and afterwards to the main institute at Chelsea. In 1909 he succeeded George Dean as chief bacteriologist, and on the retirement of Sir Charles Martin in 1930 he was appointed director of the Lister Institute.