Artenstein, Andrew W.: The discovery of viruses: advancing science and medicine by challenging dogma. (International Journal of Infectious Diseases, Volume 16, Issue 7, July 2012, pages: e470-e473). DOI:10.1016/j.ijid.2012.03.005. Andrew W. Artenstein: "By 1895 Beijerinck had returned to academia after leaving the Agricultural School for a 10-year stint in industrial microbiology in Delft, the South Holland birthplace of van Leeuwenhoek, one of the founding fathers of microbiology. During his first years at the Technical University of Delft, Beijerinck resumed the research on tobacco mosaic disease that he had started while working with Mayer. Even then, he had appreciated that the affliction was microbial in nature, although he felt that the actual agents had yet to be discovered. Beijerinck's investigations at Delft proved fruitful; he not only confirmed the infectivity of the contagium vivum fluidum—soluble living germ—despite filtration, but he importantly demonstrated that unlike bacteria, the culprit of tobacco disease of plants was incapable of independent growth, requiring the presence of living, dividing host cells in order to replicate."
