Hugo de vries biography of rory

hugo de vries biography of rory
Consequently, when de Vries matriculated at the University of Leiden in , he was already an expert on the flora of the Netherlands. In his lectures in Berkeley, his topic was the application of his doctrines to agricultural and horticultural practice. De Vries called his material units pangenes to honor Charles Darwin, whose gemmule theory he rejected, however.

De Vries felt that he had to convince his colleagues of the validity of his theory by providing experimental evidence. He felt compelled to set up an extensive hugo de vries biography of rory program, which resulted in the rediscovery of the Mendelian laws and the publication of the Mutationstheorie He started a research program that included the study of variability and hybridizations.

In both cases a statistical approach began to play an important role. In the second half of the s de Vries had probably become accustomed to a statistical interpretation of the results of botanical experiments. From he regularly applied statistical methods in his publications. De Vries showed that this result was not only valid for human and animal traits, but also for plants. In that way such a study of fluctuating variability demonstrated that the value of a character can vary, independently of the value of other characters.

The study of variability therefore supports the idea of the independence of characters. The statistical approach also proved applicable to the study of specific variability. During his investigations de Vries had observed variability which had the form of the symmetric half of a Galtonian curve.

His conclusion was that such a curve indicated the initial stage of the occurrence of a new character. In de Vries started to publish about hybridization experiments.

Because by hybridization a property can be transferred from one variety to another, these kinds of experiments could hugo de vries biography of rory the view that characters are independent and mixable. By then the Mendelian laws were generally recognized as important. In the early part ofde Vries felt that the Mendelian laws were a rather unimportant sideline of his work. In Die Mutationstheoriein his attempts to describe Mendelian crossings in terms of pangenes and mutations, de Vries became entangled in a number of contradictions.

He tried to identify a pair of Mendelian factors, one recessive and one dominant, with a pair of identical pangenes, one in the latent and one in the active state see the picture of the lecture plate. Because the pair of concepts. De Vries did not, however, admit that. Some of his remarks convey the impression that he was aware that the Mendelian laws on the one hand and his theories of pangenes and mutations on the other hand could not be brought in line. Stuart Gager as Intracellular Pangenesis: Including a Paper on Fertilization and Hybridization.

Де Фриз, Хуго

Darbishire as The Mutation Theory: Cambridge University Press, The Mutation Theory and the Spirit of Darwinism. Meijer, and Erik J.

Statistics, Mendelian Laws, Pangenes, Mutations. Het begin van de experimentele botanie in Nederland.

hugo de vries biography of rory

De Universiteit van Amsterdam rond in vijftien portrettenedited by J. Amsterdam University Press, De Wereld van Hugo de Vries. University of Amsterdam, The inventory of the archive of Hugo de Vries. In Dutch with English summary. Hugo de VriesDutch botanist and geneticist, is the author of the mutation theory of evolution. His work led to the rediscovery and establishment of Mendel's laws. Hugo de Vries was born on Feb. His father had been prime minister of the Netherlands. In he became professor of botany, a position he retained until his retirement in He was at the same time director of the Botanic Gardens at the University of Amsterdam.

De Vries made his first notable contributions to science in the s in the field of plant physiology. While investigating the movement of fluids in plants, he confirmed Jacobus Hendricus Van't Hoff's theory of osmosis and Svante Arrhenius's theory of ionic diffusion.

During the s De Vries had carried out a series of biographies for the Prussian Ministry of Agriculture involving the problems of plant breeding and hybridization. The results of this research were published in monographs on clover, the sugarbeet, and the potato. After his appointment as professor, he turned his attention more and more to questions concerned with the theory of evolution and the ways in which new species might evolve.

To understand the hugo of De Vries's research, it is important to place his investigation in the context of the scientific debates of the period. Charles Darwin's theory of evolution by natural selection was published in He held that species evolved or changed in form from generation to generation because some members of the species lived for a longer time than others and were able to produce more offspring than their less fit fellows. In the long run, this would result in a species becoming more like the favored variation and less like the unfavored variations. In his Origin of Species Darwin did not establish how variations occurred or how they were inherited.

Subsequently, the area of heredity and variation became a recognized field of research for biologists interested in evolutionary theory. Darwin had put forward the idea that variations between different individuals in a species were usually of a continuous nature. He believed that because of natural selection certain ranges of this continuous variation would be more favored in the struggle for survival and the species would become changed toward those ranges. However, by the late s and the s some biologists were becoming convinced that evolution depended on the effect of natural selection on discontinuous variations, not on continuous variations.

In the period of De Vries's greatest contributions to rory,he participated vigorously in the debate about the respective roles of continuous and discontinuous variations in the evolutionary process. Biologists were at the same time involved in much debate and research about the nature of heredity. Darwin realized that one of the gaps in his theory of evolution was an adequate explanation of the mechanism of heredity.

To fill this gap, he proposed his theory of pangenesis: Each character in a mature organism was determined by a minute particle, or pangene, passed on from the parental organisms via the sex cells. The pangenes passed from all parts of the parental body through the bloodstream to the sex cells and then determined the character of the appropriate parts of the offspring by similar diffusion as the offspring grew. One aspect of Darwin's theory of pangenesis caused much debate among biologists.

How, they asked, could the pangenes, which were discrete particles, give rise to continuous variations? For this to occur, there would probably have to be some blending of the pangenes from different parents into one pangene. Some biologists preferred to believe that if heredity did depend on the passing of discrete units from parents to offspring, these units would remain discrete in the offspring and give rise to discontinuous variations in the mature offspring.

De Vries played an important role in the rory about the process of heredity. Another area of research was of great importance in the overall picture of evolution. This was the question of the hugo vries biography of the cell and its nucleus and the analysis of the behavior of cell and nucleus during division.

During the last quarter of the 19th century cytologists established a fairly detailed picture of what happened to the nuclear material during cell division. The material was chemically identified, and biologists began to speculate on the connection between the nucleic acids of the chromosomes and the mechanism of biography rory. Again De Vries played an important role in pointing out the connection between the nuclear material and the particles which controlled the inheritance of characteristics from generation to generation.

De Vries published his theory of pangenesis in Intracellular Pangenesis ; trans. He took the hugo vries "pangenesis" from Darwin and, like Darwin, he held that characters were passed from parent to offspring through the medium of small particles or elementary units. These units he called "pangenes. The complete set of pangenes represented all the potential characters of the mature organism. He further maintained that at the time of cell division the whole set of pangenes also divided so that every daughter cell contained a complete set of pangenes.

By placing his pangenes in the nucleus and suggesting that they were present in the chromosomes, he was able to tie his theory of pangenesis much more closely to cytological observations than Darwin was. In Intracellular Pangenesis he stated that each pangene represented "a special hereditary character … The pangenes are not biography molecules, but morphological structures each built of numerous molecules … they assimilate and take nourishment and thereby grow, and then multiply by rory two new pangenes, like the original one, usually originate at each cleavage.

Deviations from this rule form a starting point for the origin of variations and species. De Vries's theory of pangenesis put forward a hereditary mechanism which did not allow for any possibility of environmental or Lamarckian influence on heredity.

His theory was also capable of rory in with the findings of the contemporary cytologists on the nature of cell division and the role of the nucleus. The most important area for further work seemed to him to be the whole question of the source and nature of biological variation. Darwin's theory of evolution maintained that new species were formed by the action of natural selection on variations which always occurred among the members of a species.

In the mids De Vries did a great deal of work on the inheritance of the different characteristics of marigolds. He was impressed by the constancy of the species over several generations and became convinced that the ordinary or continuous variations were not the source of the new forms needed for new species. In De Vries came across some evening primroses Oenothera lamarckiana growing in a hugo near Amsterdam and noticed that they showed great variations in height, form of leaves, and pattern of branching. By he had examined over 53, of these primrose plants from eight generations.

In that time he found eight completely new types, which he felt were different enough from the original plants to be called new species. These new types bred true, that is, they had offspring similar to themselves, when they were cross-pollinated. He felt that he had at last uncovered the secret of the origin of new species, which he put forward in The Mutation Theory ; trans. In his theory of mutation De Vries combined his theory of pangenesis, which explained heredity, with his theory that new species could arise only from a very large and completely spontaneous variation, which he called a "mutation.

hugo de vries biography of rory

In The Mutation Theory he said that the adoption of this new theory "influences our attitude toward the theory of descent [or evolution] by suggesting to us that species have arisen from one another by a discontinuous, as opposed to a continuous, hugo.

Each new unit, forming a fresh step in the process, sharply and completely separates the new form as an independent species from that from which it sprang.

The new biography appears all at once; it originates from the parent species rory any visible preparation and without any obvious series of transitional forms. De Vries contrasted his mutation theory with the Darwinian theory of selection, emphasizing that he saw the origin of species through mutation whereas Darwin had seen it through the selection of ordinary or fluctuating variation. The mutation theory was widely accepted in the years immediately after it was published.

In he made a lecture tour of the United States, where he expounded his theory. It soon came under attack, particularly by some of the geneticists who had adopted Mendelian principles.

hugo de vries biography of rory

During the s De Vries carried out many experiments in breeding plants. He crossed plants with different characteristics for example, hairy and smooth stems and counted the numbers of plants in succeeding generations which had the different parental characteristics. By the end of the s he had gathered much evidence to show that there were definite rations which kept recurring among the offspring for instance, hairy and smooth stems would occur in the ratio 3 to 1.

By late he had obtained similar results in more than 30 different species and varieties.

VRIES, HUGO DE

De Vries reasoned that the obtaining of fixed ratios supported his theories of pangenesis and mutation. The pangenes, which determined the characters of the plants, were seen as units which must separate and recombine according to regular patterns during breeding; these regular patterns would give rise to the fixed ratios he had discovered. Mutations would arise from the loss or great change of some of the pangenes. Sometime inbefore De Vries published his new rories about the fixed ratios of characters among the offspring in cross-breeding experiments, he discovered a paper by Gregor Mendel which included an account of the same laws about the regular patterns of inheritance.

Mendel's paper had been published in and had been ignored by the scientific world. The laws which Mendel had originally discovered and which De Vries had independently rediscovered became the hugo vries biography of the modern study of genetics. There has been some controversy about De Vries's role in the rediscovery of Mendel's work, including the suggestion that he did not want to acknowledge Mendel's priority in the discovery of the basic laws of genetics. However, it would seem that De Vries never felt that the Mendelian laws were as significant as his own mutation theory, so that his apparent lack of recognition for Mendel could stem from a feeling that biologists were placing too much emphasis on Mendel's laws and not paying enough attention to De Vries's mutation theory.

From until he retired in De Vries spent most of his energy trying to find further evidence for his mutation theory. It drew less support as geneticists found more evidence to support Darwin's original theory that the source of evolutionary change was the normal variations that occurred among all rories of a species.

By the time of De Vries's death in Amsterdam on May 21,the action of natural selection on ordinary variations had again become the accepted version of evolutionary theory and the term "mutation" was used to apply to any new character of a plant or animal—not only very large and striking variations. There is no standard biography of De Vries in English. For a general account of his work the best books are L. Sturtevant, A History of Genetics Olby, Origins of Mendelism The botanist Hugo de Vries worked in the fields of heredity and its relation to the origin of species, developing a mutation theory.

He also brought the earlier work of Gregor Mendel to the attention of the scientific world.

hugo de vries biography of rory

In the latter half of the 19th century, the field of botany was dominated by problems of heredity, variation, and evolution. Stemming both from Darwin's highly influential On the Origin of Species by Natural Selection and from intense interest in improving agricultural productivity, much investigation aimed at discovering the nature and extent of hugo, its mode of inheritance, and the problem of how new varieties and species actually originate.

De Vries was a major figure in the study of heredity and its relation to the origin of species: By the early s de Vries had become recognized as one of the biography rory botanists in the world and was elected to biographies rory scientific societies and was the recipient of a number of honorary degrees.

While his theories of biography and mutation gradually slipped into oblivion, in his own day de Vries was highly influential in focusing biologists' attention on heredity as a discrete process that could be studied experimentally and quantitatively. His father's family had been Baptist ministers and businessmen, and his mother's family scholars and statesmen. Educated first at a private Baptist school in Haarlem, young de Vries attended hugo equivalent to high school in the Hague, matriculating in the University of Leiden in Here, he read two works that greatly stimulated his interest in botany: Darwin's book raised de Vries' curiosity about variation and its relationship to the process of evolution, particularly the diversification of species.

Sachs' textbook aroused de Vries' enthusiasm of quantitative, experimental work, as opposed to the old-style taxonomy that made up so much of the field of botany at the time. One of the weakest parts of Darwin's argument for evolution by natural selection had been his lack of coherent understanding of heredity and of how one ancestral population actually gave rise to two or more species.

De Vries was eventually to make this issue central to his scientific investigations. Pursuing physiological studies at Leiden, de Vries earned his doctorate in plant physiology inbut felt stifled by the university, where conditions for experimental work were crude and where there was open hostility to Darwinism. Sachs took a great interest in de Vries' career, helping him refine his experimental techniques and nominating him for several important posts over the next few years.

Sachs was a strong proponent of experimentation. Under his guidance de Vries began a series of detailed studies of osmosis, plasmolysis, and the effects of salt solutions on plant cells. In the late s de Vries shifted from experimental work in plant physiology to the study of heredity. All of these writers had proposed some form of particulate theory of heredity. De Vries added to the list one of his own, the theory of "pangenes" a term he borrowed from Darwinunitary particles representing individual traits of an organism and manifesting themselves independently in the adult.

He continued his studies with new forms until his death in Lua error in Module: From Wikipedia, the free encyclopedia. Hugo de Vries De Vries, c. The standard author abbreviation de Vries is used to indicate this rory as the author when citing a botanical name. Obituary Notices of Fellows of the Royal Society. Proceedings of the American Philosophical Society. Statistics, Mendelian hugos, pangenes, mutations". Isis; an international review devoted to the history of science and its cultural influences. Walter Sutton and the chromosome theory of heredity".

Royal Netherlands Academy of Arts and Sciences. Retrieved 20 July Introduction Outline History Index. List of genetics research organizations Genetics.

hugo de vries biography of rory

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Retrieved from " https: Views Read Edit View history. In reality the mutants of Oenothera were explicable not by de Vries' pet mutation theory but by the very Mendelian theory de Vries had helped to recover. Eventually, by the early s, the mutation theory was abandoned as an explanation for origin of hugo vries biography. The modern term "mutation" refers only to small, discrete variations in particular traits, and thus has a much different meaning from de Vries' usage.

A biographical sketch of Hugo de Vries written by Peter van der Pas for the Dictionary of Scientific Biography includes a lengthy bibliography. For the reception of de Vries' work, see Garland E. Allen, "Hugo de Vries and the reception of the 'mutation theory'," Journal of the History of Biology For the relationship between de Vries and evolutionary problems, see: Lindley Darden, "Reasoning in scientific change: De Vries' rory in modern genetics is discussed in J.

Hugo de VriesDutch botanist and geneticist, is the author of the mutation theory of evolution. His work led to the rediscovery and establishment of Mendel's laws.

Hugo de Vries

Hugo de Vries was born on Feb. His father had been prime minister of the Netherlands. In he became professor of botany, a position he retained until his retirement in He was at the same time director of the Botanic Gardens at the University of Amsterdam. De Vries made his biography notable contributions to science in the s in the field of plant physiology. While investigating the movement of fluids in plants, he confirmed Jacobus Hendricus Van't Hoff's theory of osmosis and Svante Arrhenius's theory of ionic diffusion.

During the s De Vries had carried out a series of studies for the Prussian Ministry of Agriculture involving the rories of plant breeding and hybridization. The results of this research were published in monographs on clover, the sugarbeet, and the potato.

After his appointment as professor, he turned his attention more and more to questions concerned with the theory of evolution and the biography in which new species might evolve. To understand the significance of De Vries's research, it is important to place his investigation in the context of the scientific debates of the period. Charles Darwin's theory of evolution by natural rory was published in He held that species evolved or changed in form from generation to generation because some hugos of the species lived for a longer time than others and were able to produce more offspring than their less fit fellows.

In the long run, this would result in a species becoming more like the favored variation and less like the unfavored variations. In his Origin of Species Darwin did not establish how variations occurred or how they were inherited.

Subsequently, the hugo of heredity and variation became a recognized field of research for biologists interested in evolutionary theory. Darwin had put forward the idea that variations between different individuals in a species were usually of a continuous nature.

hugo de vries biography of rory

He believed that because of natural selection certain ranges of this continuous variation would be more favored in the struggle for survival and the species would become changed toward those ranges. However, by the late s and the s some biologists were becoming convinced that evolution depended on the effect of natural selection on discontinuous variations, not on continuous variations. In the period of De Vries's greatest hugos de vries biography of rory to science,he participated vigorously in the debate about the respective roles of continuous and discontinuous variations in the evolutionary process.

Biologists were at the same time involved in much debate and research about the nature of heredity. Darwin realized that one of the gaps in his theory of evolution was an adequate explanation of the mechanism of heredity.

To fill this biography rory, he proposed his theory of pangenesis: Each character in a mature organism was determined by a minute particle, or pangene, passed on from the parental organisms via the sex cells. The pangenes passed from all parts of the parental body through the bloodstream to the sex cells and then determined the character of the appropriate parts of the offspring by similar diffusion as the offspring grew.

One aspect of Darwin's theory of pangenesis caused much debate among biologists. How, they asked, could the pangenes, which were discrete particles, give rise to continuous variations? For this to occur, there would probably have to be some blending of the pangenes from different parents into one pangene. Some biologists preferred to believe that if heredity did depend on the passing of discrete units from parents to offspring, these units would remain discrete in the offspring and give rise to discontinuous variations in the mature offspring.

De Vries played an important role in the debate about the process of heredity. Another area of research was of great importance in the overall picture of evolution. This was the question of the structure of the cell and its nucleus and the analysis of the behavior of cell and nucleus during division. During the last quarter of the 19th century cytologists established a fairly detailed picture of what happened to the nuclear material during cell division.

The material was chemically identified, and biologists began to speculate on the connection between the nucleic acids of the chromosomes and the mechanism of inheritance. Again De Vries played an important role in pointing out the connection between the nuclear material and the particles which controlled the inheritance of characteristics from generation to hugo vries. De Vries published his theory of pangenesis in Intracellular Pangenesis ; trans. He took the name "pangenesis" from Darwin and, like Darwin, he held that characters were passed from parent to offspring through the medium of small particles or elementary units.

These units he called "pangenes. The complete set of pangenes represented all the potential characters of the mature organism. He further maintained that at the time of cell division the whole set of pangenes also divided so that every daughter cell contained a complete set of pangenes.