|
কোরেনস এবং [[এরিখ ফন স্চারম্যাক]] উভয়কেই এখন মেন্ডেলের সূত্র পুনরায় আবিষ্কারের জন্য কৃতীত্ব দেওয়া হয়। কারেনস ছিলেন [[Carl Wilhelm von Nägeli | নাগেলি]] এর শিক্ষার্থী। মেন্ডেল তাঁর সাথে মটর গাছ সম্পর্কে তাঁর কাজের কথা লিখেছিলেন। কিন্তু তাঁরা এর তাৎপর্য বুঝতে পারেন নি এবং কাকতালীয়ভাবে স্চারম্যাকের দাদু ছাত্রাবস্থায় ভিয়েনায় মেন্ডেলকে উদ্ভিদবিদ্যায় শিক্ষাদান করে ছিলেন।
==মিউটেশন তত্ত্ব==
In his own time, De Vries was best known for his [[mutation theory]]. In 1886, he had discovered new forms among a display of the [[oenothera|evening primrose]] (''Oenothera lamarckiana'') growing wild in an abandoned potato field near Hilversum, having escaped a nearby garden.<ref>de Vries, Hugo. ''Die Mutationstheorie. Versuche und Beobachtungen über die Entstehung von Arten im Pflanzenreich'', Leipzig, Veit & Comp., 1901-03.</ref> Taking seeds from these, he found that they produced many new varieties in his experimental gardens; he introduced the term '''mutations''' for these suddenly appearing variations. In his two-volume publication ''The Mutation Theory'' (1900–1903) he postulated that evolution, especially the origin of species, might occur more frequently with such large-scale changes than via Darwinian gradualism, basically suggesting a form of [[Saltation (biology)|saltationism]]. De Vries's theory was one of the chief contenders for the explanation of how evolution worked, leading, for example, [[Thomas Hunt Morgan]] to study mutations in the fruit fly, until the [[modern synthesis (20th century)|modern evolutionary synthesis]] became the dominant model in the 1930s. During the early decades of the twentieth century, de Vries' theory was enormously influential and continued to fascinate non-biologists long after the scientific community had abandoned it.<ref>{{cite journal |title=Mutant Utopias: Evening Primroses and Imagined Futures in Early Twentieth-Century America |journal=Isis |date=September 2013 |last=Endersby |first=Jim |volume=104 |issue=3 |pages=471–503 |doi=10.1086/673270 |pmid=24341261 |s2cid=12125667 |url=http://sro.sussex.ac.uk/57891/1/Mutant%20Utopias%20%282013%29.pdf }}</ref> The large-scale primrose variations turned out to be the result of various chromosomal abnormalities, including [[ring chromosomes]], [[Hermann_Joseph_Muller|balanced lethals]] and chromosome duplications ([[polyploidy]]), while the term mutation now generally is restricted to discrete changes in the DNA sequence. However, the popular understanding of "mutation" as a sudden leap to a new species has remained a staple theme of science fiction, e.g. the [[X-Men movies]] (and the comic books that preceded them).<ref>{{cite encyclopedia |url=http://www.sf-encyclopedia.com/entry/mutants |title=Mutants |last1=Stableford |first1=Brian M. |last2=Langford |first2=David |encyclopedia=The Encyclopedia of Science Fiction |date=2018-08-12 |accessdate=2018-09-08 }}</ref>
Finally, in a published lecture of 1903 (''Befruchtung und Bastardierung'', Veit, Leipzig), De Vries was also the first to suggest the occurrence of recombinations between [[homologous chromosome]]s, now known as [[chromosomal crossover]]s, within a year after chromosomes were implicated in Mendelian inheritance by [[Walter Sutton]].<ref>{{Cite journal
| last1 = Crow | first1 = E. W.
| last2 = Crow | first2 = J. F.
| title = 100 years ago: Walter Sutton and the chromosome theory of heredity
| journal = Genetics
| volume = 160
| issue = 1
| pages = 1–4
| year = 2002
| pmid = 11805039
| pmc = 1461948
}}</ref>
==তথ্যসূত্র==
|
