HENRY PERCY MARKS, a member of the scientific staff of the Medical Research Council at the National Institute for Medical Research, died on September 13 after a short illness. After serving in the Navy in the War of 1914–18, Marks joined the Medical Research Council as an attached worker at Hampstead in 1922, and was appointed a member of the staff in 1927. His work at Hampstead was mainly concerned with insulin and carbohydrate metabolism although, in collaboration with others at the Institute, he also carried out interesting work on the mechanism of action of calciferol. More recently, Marks had become interested in the influence of the pituitary gland on carbohydrate metabolism and had published a number of papers on this aspect of the subject. For the two years immediately preceding his death he had been assisting in research work of national importance in connexion with the War, and had undertaken the arduous duties involved with the enthusiasm of a man many years younger. His untimely death will be mourned by his many colleagues and friends at Hampstead and elsewhere.