Letter from Howard Walter Florey to J C Woodruff, Merck and Co Incorporated, Rahway, New Jersey Sympathises with Merck's difficulties in making penicillin - hopes they are now getting results - delighted that Heatley was of use - says Heatley would probably be willing to return in a year or so - Heatley is to work on naturally occuring bacterial substances. 22 July 1942