VRIES, HUGO (MARIE) DE

born , Feb. 16, 1848, Haarlem, Neth. died May 21, 1935, near Amsterdam Dutch botanist and geneticist who introduced the experimental study of organic evolution. His rediscovery in 1900 (simultaneously with the botanists Carl Correns and Erich Tschermak von Seysenegg) of Gregor Mendel's principles of heredity and his theory of biological mutation, though considerably different from a modern understanding of the phenomenon, resolved ambiguous concepts concerning the nature of variation of species that, until then, had precluded the universal acceptance and active investigation of Charles Darwin's system of organic evolution. Educated at the universities of Leiden, Heidelberg, and Wrzburg, de Vries became a professor at the University of Amsterdam in 1878, serving there until 1918. In 1886 de Vries noticed wild varieties of the evening primrose (Oenothera lamarckiana) that differed markedly from the cultivated species. This suggested to de Vries that evolution might be studied by a new, experimental method rather than by the old method of observation and inference. He discovered in his cultivation of the evening primrose new forms or varieties appearing randomly among the host of ordinary specimens. He gave the name mutations to these phenomena, which he showed to arise suddenly, as distinct from Darwin's variation of species through natural selection. De Vries believed these varieties to be an example of an evolution that could be studied experimentally and conceived of evolution as a series of abrupt changes radical enough to bring new species into existence in a single leap. De Vries' research into the nature of mutations, summarized in his Die Mutationstheorie (1901-03; The Mutation Theory), led him to begin a program of plant breeding in 1892, and eight years later he drew up the same laws of heredity that Mendel had. While surveying literature on the subject, de Vries discovered the Austrian monk's paper of 1866 on the breeding of garden peas, and he was careful to attribute the original discovery of the laws of heredity to Mendel in his subsequent publications. De Vries also contributed to knowledge of the role played in plant physiology by osmosis, and in 1877 he demonstrated a relation between osmotic pressure and the molecular weight of substances in plant cells. Among de Vries' other works are Intracellular Pangenesis (1889) and Plant Breeding (1907).