De Vries, Hugo (Marie) (1848-1935)

Dutch botanist who conducted important research on osmosis in plant cells and was a pioneer in the study of plant evolution. His work led to the rediscovery of Austrian biologist Gregor Mendel's laws and the discovery of spontaneously occurring mutations. De Vries was born in Haarlem and studied medicine at Heidelberg and Leiden. He spent most of his academic career at the University of Amsterdam, and was professor of botany there 1881-1918. Using a plant called Oenothera lamarckiana, he began a programme of plant-breeding experiments 1892. In 1900, he formulated the same laws of heredity that - unknown to de Vries - Mendel had discovered 1866. De Vries further found that occasionally an entirely new variety of Oenothera appeared and that this variety reappeared in subsequent generations. De Vries called these new varieties mutations. He assumed that, in the course of evolution, those mutations that were favourable for the survival of the individual persisted unchanged until other, more favourable mutations occurred. He summarized this work in Die Mutationstheorie/The Mutation Theory 1901-03.