Wilhelm Johannsen
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{{Infobox_Scientist
|name = Wilhelm Ludvig Johannsen
|image = Wilhelm Johannsen 1857-1927.jpg
|birth_date = {{birth date|1857|02|03}}
|birth_place = [[Elsinore]], [[Denmark]]
|nationality = {{DEN}}
|death_date = {{death date and age|1927|11|11|1857|02|03}}
|death_place = [[Copenhagen]], [[Denmark]]
|field = [[Genetics]]<br>[[Plant physiology]]
|work_institution = [[University of Copenhagen]]
|alma_mater = [[University of Copenhagen]]
|doctoral_advisor =
|doctoral_students =
|known_for = proving the constancy of the [[genome]]<br>defining [[gene]], [[genotype]] and [[phenotype]]
|prizes =
|footnotes =
}}
'''Wilhelm Johannsen''' ([[February 3]], [[1857]] - [[November 11]], [[1927]]) was a [[Denmark|Danish]] [[botanist]], plant physiologist and [[geneticist]]. He was born in Copenhagen. Very young, he was apprenticed to a [[pharmacist]] in 1872 and worked in [[Denmark]] and [[Germany]], passing his pharmacist's exam in 1879. In 1881, he became assistant in the chemistry department at the [[Carlsberg Laboratory]] under the chemist [[Johan Kjeldahl]]. Johannsen studied the [[metabolism]] of [[dormancy]] and [[germination]] in [[seed]]s, [[tuber]]s and [[bud]]s. He showed that [[dormancy]] could be broken by various [[anesthetic]] compounds, such as [[diethyl ether]] and [[chloroform]].
In 1892, he was appointed lecturer at [[University of Copenhagen Faculty of Life Sciences|Royal Veterinary and Agricultural University]] and later became professor of [[botany]] and [[plant physiology]]. He taught plant physiology<ref>[[Eugenius Warming|Warming, Eug.]] & W. Johannsen (1895) Den almindelige Botanik (General Botany): En Lærebog, nærmest til Brug for Studerende og Lærere. 3rd edn, [[Copenhagen|Kjøbenhavn]]. 4th edn by Warming and Johannsen 1900-01). German edn 1907-09: Lehrbuch der allgemeinen Botanik (from the 4th edn, by E. P. Meinecke). Berlin, Borntraeger. 667 pp.</ref>. His most well-known research concerned so-called ''pure lines'' of the self-fertile [[common bean]]. He was able to show that even in [[population]]s [[homozygote|homozygous]] for all traits, i.e. without genetic variation, seed size followed a [[normal distribution]]. This was attributable to resource provision to the mother plant and to the position of seeds in [[pod]]s and of pods on the plant. This led him to coin the terms ''[[phenotype]]'' and ''[[genotype]]''. His findings led him to oppose contemporary [[Darwinism|Darwinists]], most notably [[Francis Galton]] and [[Karl Pearson]], who held the occurrence of [[normal distribution|normal distributed]] trait variation in [[population]]s as proof of gradual genetic variation on which selection could act<ref>[http://dx.doi.org/10.1111/j.1600-0498.1979.tb00589.x Roll-Hansen, Nils (1979) The Genotype Theory of Wilhelm Johannsen and its Relation to Plant Breeding and the Study of Evolution. Centaurus 22 (3): 201–235]</ref>. Only with the [[modern evolutionary synthesis]], it was established that variation need tobe [[heritable]] to act as the raw material for [[selection]].
The terms ''[[phenotype]]'' and ''[[genotype]]'' were created by Wilhelm Johannsen and first used in his paper ''Om arvelighed i samfund og i rene linier''<ref>Johannsen, W. (1903) Om arvelighed i samfund og i rene linier. Oversigt over det [[Kongelige Danske Videnskabernes Selskab]]s Forhandlinger, vol. 3: 247-270.</ref> and in his book ''Arvelighedslærens Elementer''<ref>Johannsen, W.L. (1905) Arvelighedslærens elementer (The Elements of Heredity). Copenhagen.</ref>. This book was rewritten, enlarged and translated to German as ''Elemente der exakten Erblichkeitslehre''<ref>Johannsen, W. (1909) Elemente der exakten Erblichkeitslehre. Gustav Fischer, Jena.</ref>. It was in this book Johannsen introduced the term ''[[gene]]''. This term was coined in opposition to the then common ''pangene'' that stemmed from [[Charles Darwin|Darwin's]] theory of [[pangenesis]]. The book became one of the founding texts of genetics.
Also in 1905, Johannsen was appointed professor of [[plant physiology]] at the [[University of Copenhagen ]], becoming vicechancelor in 1917. In December 1910, Johannsen was invited to give an address before the [[American Society of Naturalists]]. This talk was printed in the [[American Naturalist]]<ref>[http://links.jstor.org/sici?sici=0003-0147%28191103%2945%3A531%3C129%3ATGCOH%3E2.0.CO%3B2-M Johannsen, W. (1911) The Genotype Conception of Heredity. American Naturalist 45 (531): 129-159.]</ref>. In 1911, he was invited to give a series of four lectures at [[Columbia University]]<ref>[http://links.jstor.org/sici?sici=0036-8075%2819111013%293%3A34%3A876%3C484%3APJCL%3E2.0.CO%3B2-3 Anon. (1911) Professor Johannsen's Columbia Lectures. Science N.S. 34 (876): 484.]</ref>
==Miscellaneous==
Corresponding member of the [[Academy of Natural Sciences|Academy of Natural Sciences of Philadelphia]] (elected 1915).
==References==
{{Reflist}}
*Anker, Jean (1932) Wilhelm Johannsen, pp. 177-180 in: Meisen, V. Prominent Danish Scientists through the Ages. University Library of Copenhagen 450th Anniversary. Levin & Munksgaard, Copenhagen.
*[http://links.jstor.org/sici?sici=0306-3127%28198311%2913%3A4%3C481%3ATDOSGA%3E2.0.CO%3B2-2 Roll-Hansen, Nils (1983) The Death of Spontaneous Generation and the Birth of the Gene: Two Case Studies of Relativism. Social Studies of Science 13 (4): 481-519.]
*[http://links.jstor.org/sici?sici=0306-3127%28199111%2921%3A4%3C649%3AOTROJP%3E2.0.CO%3B2-0 Kim, Kyung-Man (1991) On the Reception of Johannsen's Pure Line Theory: Toward a Sociology of Scientific Validity. Social Studies of Science 21 (4): 649-679.]
==External links==
*[http://www.wjc.ku.dk/ Wilhelm Johannsen Centre for Functional Genome Research]
*[http://www.wjc.ku.dk/wilhelm/index.php?subpage=gallery Image gallery]
*[http://www.wjc.ku.dk/library/video/original.avi 6 min silent mowie showing Johannsen in action as teacher and scientist]
{{DEFAULTSORT:Johannsen, Wilhelm}}
[[Category:1857 births|Johannsen, Wilhelm]]
[[Category:1927 deaths|Johannsen, Wilhelm]]
[[Category:Danish botanists|Johannsen, Wilhelm]]
[[Category:Botanists|Johannsen, Wilhelm Ludvig]] <!--no author abbrev, so please leave in this cat-->
[[Category:Geneticists|Johannsen, Wilhelm Ludvig]]
[[Category:Agriculture educators]]
[[Category:Danish science writers]]
[[Category:University of Copenhagen alumni]]
[[Category:University of Copenhagen faculty]]
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