Raymond Rettew (on right) with Dr. Desmond Biel, holding sterile culture with seed spores of Penicillin Notatum, circa 1945.

Credit: Courtesy of the Chester County Historical Society, Westchester, Pa.

By the fall of 1943, Raymond Rettew's Walnut Street Laboratory in West Chester PA, utilizing Rettew's surface culture technique, was producing much of the penicillin made in the United States.