Walther Flemming

Walther Flemming
File:Walther flemming 2.jpg this picture shows Walther Flemming
Born	21 April 1843 Sachsenberg, Mecklenburg-Schwerin
Died	4 August 1905 Kiel
Nationality	German
Alma mater	University of Rostock
Known for	Cytogenetics, mitosis, chromosomes, chromatin

Walther Flemming (21 April 1843 – 4 August 1905) was a German biologist and a founder of cytogenetics.

He was born in Sachsenberg (now part of Schwerin) as the fifth child and only son of the psychiatrist Carl Friedrich Flemming (1799–1880) and his second wife, Auguste Winter. He graduated from the Gymnasium der Residenzstadt, where one of his colleagues and lifelong friends was writer Heinrich Seidel.

Career

Flemming trained in medicine at the University of Rostock, graduating in 1868. Afterwards, he served in 1870–71 as a military physician in the Franco-Prussian War. From 1873 to 1876 he worked as a teacher at the University of Prague. In 1876 he accepted a post as a professor of anatomy at the University of Kiel. He became the director of the Anatomical Institute and stayed there until his death.

With the use of aniline dyes he was able to find a structure which strongly absorbed basophilic dyes, which he named chromatin. He identified that chromatin was correlated to threadlike structures in the cell nucleus – the chromosomes (meaning coloured bodies), which were named thus later by German anamist Wilhelm von Waldeyer-Hartz (1841–1923). The Belgian scientist Edouard Van Beneden (1846–1910) had also observed them, independently.

Flemming investigated the process of cell division and the distribution of chromosomes to the daughter nuclei, a process he called mitosis from the Greek word for thread. However, he did not see the splitting into identical halves, the daughter chromatids. He studied mitosis both in vivo and in stained preparations, using as the source of biological material the fins and gills of salamanders. These results were published first in 1878 and in 1882 in the seminal book Zellsubstanz, Kern und Zelltheilung (1882; Cell substance, nucleus and cell division). On the basis of his discoveries, Flemming surmised for the first time that all cell nuclei came from another predecessor nucleus (he coined the phrase omnis nucleus e nucleo, after Virchow's omnis cellula e cellula).

Polytene chromosomes in a Chironimus salivary gland cell, one of over 100 drawings from Flemming's book Zellsubstanz, Kern und Zelltheilung, 1885

Illustrations of cells with chromosomes and mitosis, from the book Zellsubstanz, Kern und Zelltheilung, 1882

Flemming is famously known for the work outside of his work that he did. He weekly feed those who were homeless, donating every year, 20% of his salary to homeless shelters. He taught especially young children who were too poor to attend school about mathematics and science.

Flemming was unaware of the work of Gregor Mendel (1822–84) on heredity, so he did not make the connection between his observations and genetic inheritance. Two decades would pass before the significance of Flemming's work was truly realized with the rediscovery of Mendel's rules. His discovery of mitosis and chromosomes is considered one of the 100 most important scientific discoveries of all time, and one of the 10 most important discoveries in cell biology (together with August Weismann's (1834–1914) discovery of meiosis, Theodor Schwann (1808–90) and Matthias Schleiden's (1804–81) cell theory and Alfred Sturtevant's (1866–1945) first genetic maps).

Flemming's name is honoured by a medal awarded by the German Society for Cell Biology (Deutschen Gesellschaft für Zellbiologie).

Further reading

• and Reprinted in J. Cell Biol. 25:581–589 (1965).
• Flemming, W. Zur Kenntniss der Zelle und ihrer Theilungs-Erscheinungen. In: Schriften des Naturwissenschaftlichen Vereins für Schleswig-Holstein 3 (1878), 23–27. (Reprinted in )
• Carlson, E.A. The Analysis of Mitosis Shifts Attention to the Chromosomes. In: Mendel's Legacy. The Origins of Classical Genetics. p. 24-5, CSHL Press, 2004. ISBN 0-87969-675-3.

External links

• Walther Flemming Biography. Lasker Labs
• Zellsubstanz, Kern und Zelltheilung. Original text of the book, as PDF (In German).
• Walter Flemming Medaille. In PDF, in German.
• Hardy, P. A., Zacharias, H. (2008): Walther Flemming und die Mitose: Der Beitrag seiner ersten Kieler Jahre. Schr. Naturwiss. Ver. Schlesw.-Holst. 70, 3–15. Paper about his first description of mitosis. In German.