Letter from Bernard D Davis, Department of Bacteriology and Immunology, Harvard Medical School, Boston to Howard Walter Florey Says he and his colleagues are completing a textbook on microbiology and need photographs - grateful if Florey could supply copies of Fleming's photograph of penicillin production on a plate and an example of antibiotic assay, such as in paper by Florey and Chain in Endeavour - enjoyed meeting Florey. 4 August 1965