Letter from Howard Walter Florey to K C Turpin, Secretary of the Faculties, University Registry, Oxford J L Gowans started work on thesis on mode of action of antibacterial substances in vivo - Gowans made good progress but had to give up work for 10 months because of illness - he returned to work on 16 May 1950 - Gowans should not over exert himself for a year or two - thesis involved experiments lasting 24 hours - does not want Gowans to continue such experiments - asks if Medicine Board would allow Gowans to submit the thesis in two parts, the first part on work done before his illness and the second on the investigation of the properties of nisin and other antibiotics - comments on this second subject. 22 September 1950