Letter from Richard P Harris, Royal Automobile Club, London to Howard Walter Florey Has read about penicillin - works on water supplies - at a supply on the Gold Coast, improved bacteriological results were reported - describes growth of algae mixed with a fungus on the sedimentation tanks - attempted to isolate active substance - small yield - will send cultures if Florey wishes - would like references about isolation and identification of mould products. Manuscript note: answered 11 November 1942 - none available. 10 November 1942