During the Second World War Arber found it difficult to maintain her small laboratory, due to health problems and supplies were becoming more difficult to obtain. Further, she did not believe it was "fair to her neighbours" to have flammable laboratory materials in her home while there was a danger of wartime bombing. This led to her decision to stop performing laboratory work and to concentrate more on philosophical and historical issues. Arber published work on historical botanists, including a comparison between Nehemiah Grew and Marcello Malpighi in 1942, John Ray in 1943 and Sir Joseph Banks in 1945.Flannery, M 'The Many Sides of Agnes Arber'
