Mykola Hryhorovych Kholodny ( ukr, Микола Григорович Холодний ; 22 June 1882 – 4 May 1953) was an influential microbiologist who worked at the

University of Kyiv Kyiv University or Shevchenko University or officially the Taras Shevchenko National University of Kyiv ( uk, Київський національний університет імені Тараса Шевченка), colloquially known as KNU ...

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

in the

USSR The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...

during the 1930s. He is known for the

Cholodny–Went model In botany, the Cholodny–Went model, proposed in 1927, is an early model describing tropism in emerging shoots of monocotyledons, including the tendencies for the shoot to grow towards the light ( phototropism) and the roots to grow downward ( ...

, which he developed independently with

Frits Warmolt Went Frits Warmolt Went (May 18, 1903 – May 1, 1990) was a Dutch biologist whose 1928 experiment demonstrated the existence of auxin in plants. Went's father was the prominent Dutch botanist F.A.F.C. Went. After graduating from the University of ...

of the

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

. Despite being associated with the same theory, the two men never actually met. Cholodny worked in the

A.V. Fomin Botanical Garden The A.V. Fomin Botanical Garden (sometimes translitterated as O.V. Fomin Botanical Garden) is one of the oldest botanical gardens in Ukraine, located in Kyiv, the capital of Ukraine.http://www.botanic.kiev.ua/#eng/ , (Ukrainian) In 1839 the Sain ...

, attached to the University of Kyiv. He was one of the pioneers of the concept that microbes adhere to surfaces, using the technique of first placing glass slides in earth for a measured time period, then using a microscope to examine the slides. The

Prokaryote A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connec ...

''Leptothrix cholodnii'' is named after him. In 1927 Cholodny proposed that the cells of the

coleoptile Coleoptile is the pointed protective sheath covering the emerging shoot in monocotyledons such as grasses in which few leaf primordia and shoot apex of monocot embryo remain enclosed. The coleoptile protects the first leaf as well as the growing ...

are first polarized under the influence of uneven exposure to light, so growth hormone can diffuse more rapidly towards the side in the shade than in any other direction. Went reached the same conclusion in 1928, and the two scientists' names have been attached to the controversial Cholodny–Went theory.

Bibliography

Selected works include: *1926 ''Die eisenbakterien : bieträge zu einer monographie'' by N Cholodny *1928 ''Über eine vermeintliche Anomalie im Wachstumsmodus der Wurzeln von Lupinus albus'' by N Cholodny *1932 ''Lichtwachstumsreaktion und Phototropismus 2'' by N Cholodny *1933 ''Zum Problem der Bildung und physiologischen Wirkung des Wuchshormons bei den Wurzeln'' by N Cholodny *1939 ''Spezielle Methoden''. In 1937 N. G. Cholodny and E. Ch. Sankewitsch published an article on ''Influence of weak electric currents upon the growth of the coleoptile'' in '' Plant Physiology''. The same year he published an article on ''Charles Darwin and the modern theory of tropisms'' in ''Science'' magazine.

References

1882 births 1953 deaths People from Tambov People from Tambovsky Uyezd Soviet botanists Members of the National Academy of Sciences of Ukraine Recipients of the Order of Lenin {{Biologist-stub