Hugo Marie de Vries

views updated

Hugo Marie de Vries


Dutch Botanist

Hugo Marie de Vries was a Dutch botanist whose work with plant species led him to rediscover Gregor Mendel's theories of heredity, and brought his concept of mutation into evolutionary theory.

De Vries was born in Haarlem, the Netherlands, on February 16, 1848. He became interested in botany, the study of plants, at an early age. In 1870, he received his Ph.D. from the University of Leiden, then continued his studies at the University of Heidelberg, where he was fortunate enough to work with noted German plant physiologist Julius von Sachs (1832-1897). He continued his research on the physiology of plant cells while serving as professor at the University of Amsterdam in 1878, a position he held until 1918.

By the late 1880s, controversy was mounting over the application of evolutionary theory to plant heredity. In 1886, while conducting experiments involving the hybridization, or cross-breeding, of plants, de Vries discovered wild varieties of the evening primrose (Oenothera lamarckiana) that differed from the cultivated species. This led him to a new method of investigating evolution—by experimentation, rather than observation alone.

De Vries found that unique variations appeared randomly within the cultivated primrose specimens, a phenomenon he labeled mutations. de Vries found that these mutations, or variations, could produce a new species within a single generation. Mutations which were favorable to the survival of the species would persist until replaced by other, even more beneficial variations. While our modern understanding of heredity and mutation have since diverted from De Vries's theories, his concepts of species variation was well received at the time, as it provided the first alternative to Darwin's theory of natural selection. Darwin's widely accepted supposition held that new species developed slowly, through tiny variations, whereas De Vries proposed that a new species could emerge more quickly.

De Vries re-discovered the research papers of Austrian monk Gregor Mendel (1822-1884), which outlined Mendel's evolutionary theory. De Vries brought Mendel's theories back into the scientific mainstream, giving his predecessor full credit. Two other botanists, Karl Correns (1864-1933) and Erich Tschermak von Seysenegg (1871-1962), simultaneously made the same discovery, but only de Vries held to his own theory of heredity. De Vries's theory strayed from that of Mendel when he proposed that independent units called pangenes carried hereditary traits. He summarized his research in his Die Mutationstheorie (The Mutation Theory) in 1901-1903.

De Vries's other work included a study of the role of osmosis in plant physiology. In 1877, he demonstrated the relationship between osmotic pressure and the molecular weight of substances in plant cells. His other writings included Intracellular Pangenesis (1889) and Plant Breeding (1907).

De Vries retired in 1918 from the University of Amsterdam, but continued his studies for several years. He died in Amsterdam in May 1935.