Clockwise from left: Agnes J. Quirk, Helen Morgenthau Fox, and Florence Hedges. Agnes J. Quirk (1884 - 1974) was an American bacteriologist, plant pathologist, and inventor. Hired by Erwin Frink Smith, senior plant pathologist of the Laboratory of Plant Pathology, USDA's Bureau of Plant Industry, Quirk became Smith's assistant in 1901 to 1927, and was head of the laboratory from 1928 to 1948. Quirk's research focused on the crown gall oxidation phenomena and culture mediums used in pathogenic analyses, working alongside Nellie A. Brown. She received a patent for the production of penicillin mold and jelly in 1952. Helen Morgenthau Fox (May 27, 1884 - January 13, 1974) was an American botanist and author of popular gardening books. Florence Hedges (August 24, 1878 - December 17, 1956) was an American plant pathologist and botanist with the USDA Bureau of Plant Industry. Much of her work involved investigations into bacteria-induced plant disease. No photographer credited, undated.