According to Hugo de Vries, the mechanism of evolution is saltation.
Hugo de Vries (1901) proposed the mutation theory of evolution and stated that evolution is a jerky process in which new species are evolved due to discontinuous sudden variations or saltation. These are the single step large mutations occurring in the population.
de Vries believed that evolution was a result of larger mutations opposed to Darwin's minor heritable variations or phenotypic variations. As mentioned, these mutations are achieved in a single step rather than multiple.