Flemming was unaware of Gregor Mendel's (1822–1884) work on heredity, so he did not make the connection between his observations and genetic inheritance. Two decades would pass before the significance of Flemming's work was truly realized with the rediscovery of Mendel's rules. His discovery of mitosis and chromosomes is considered one of the 100 most important scientific discoveries of all times, and one of the 10 most important discoveries in cell biology.