 In 1900, several botanists independently arrived at similar results in their hybridization experiments and at the same time took notice of Mendel’s original work and stated its significance in their respective publications (Olby 1966: Ch. 6). This brought the Mendelian approach and way of reasoning to the attention of those who worked with experimental crosses in contexts of either theoretical questions regarding heredity and evolution or applied problems of horticulture and scientific breeding (Bowler 1989a: Ch. 6). Much had changed in biology since Mendel’s days: first, the idea that the hereditary material is passed on independently of somatic development, codified in August Weismann’s (1834–1914) germ-line theory, was well established; second, several researchers had developed a cytological interpretation of hereditary phenomena; third, in the late nineteenth century various ideas on how to identify units transmitted through germ cells had emerged. Furthermore, on a broader social and economic scale, processes of industrialization and rationalization of food production, vaccines, and other applications had led to an increased demand for standardized biological materials (Müller-Wille &amp; Rheinberger 2012: Ch. 6). In this context, the entities and regularities identified by hybridization experiments were now taken to be the basis of heredity in general.