Letter from Howard Walter Florey to H R Ing, Department of Pharmacology, Oxford Has received Ing's letter asking about the start of penicillin work - suggests that Ing read Chapter 15 of 'Antibiotics' - did not start work on the penicilllins because of sulphonamides but difficult to deny that the existence of these probably initiated his general thinking - once it was demonstrated that chemical substances could affect bacteria in the body, no reason to think similar substances might exist. 1 October 1963