Mutation
theory that evolution progresses by quick changes rather than gradual transformations. The idea long suggested was first brought out in fullness by Professor de Vries of Amsterdam in 1901. His experiments showed that mutation, not natural selection, led to the development of new characters and new species. He showed it probable that mutation really brought into being something new, without intermediate processes and transitions. The mutant remained settled as a new species. Almost simultaneously a Russian investigator showed that the cultivated varieties of plants had come suddenly into being through mutation, without the slow and imperceptible development previously thought necessary, and the theory is now generally accepted by scientists.