Referee's report by Francis John Worsley Roughton, on a paper 'The growth, growth energy, and ageing of the chicken’s heart' by Peter Brian Medawar Sectional committee: Physiology Recommended for publication in Proceedings. It is a useful contribution to a difficult subject. Some modifications should be made. [Published in Proceedings of the Royal Society B, 1940]. Endorsed on verso as received 13 July 1940. July 1940