Ferdinand Julius Cohn (24 January 1828 – 25 June 1898) was a German
biologist. He is one of the founders of modern
bacteriology and
microbiology
Microbiology () is the branches of science, scientific study of microorganisms, those being of unicellular organism, unicellular (single-celled), multicellular organism, multicellular (consisting of complex cells), or non-cellular life, acellula ...
.
Biography
Ferdinand Julius Cohn was born in the Jewish quarter of
Breslau in the
Prussian Province of Silesia (modern-day Wrocław,
Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
). His father, Issak Cohn, was a successful merchant and manufacturer who for some time held the post of Austro-Hungarian consul. He was the elder brother of humorist and playwright
Oskar Justinus Cohn and of historian and jurist .
He was considered a
child prodigy, and could read at the age of two. He also suffered hearing impairment from a young age. He entered the in 1835 at the age or 6 or 7, and the
University of Breslau in 1842 or 1844. There he studied botany under
Heinrich Göppert and
Christian Nees von Esenbeck.
Cohn was refused admission to the University of Breslau's doctoral program because of his Jewish background. He thus continued his studies at the
University of Berlin, where he obtained a Ph.D. in 1847 with a dissertation on the
physiology
Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...
of seeds. In it he advocated for the establishment of botanical gardens dedicated to the study of plant physiology, a vision that he later played a significant role in realizing.
He returned to Breslau in 1848 and, after a delay due to his Jewish heritage, was appointed as a
privat-docent in 1850. He remained at that university for the rest of his career, obtaining the titled of professor in 1857 and, following the death of his mentor Göppert, was promoted to a full professorship in 1872.
Work
Cohn was a prolific writer, leaving behind over 150 papers, essays, and books.
In the 1850s he studied the growth and division of plant cells. In 1855 he produced papers on the sexuality of ''
Sphaeroplea annulina'' and later ''
Volvox globator''. In the 1860s he studied plant physiology in several different aspects. From 1870 onward he mostly studied bacteria. He established the use of sterile culture mediums and rediscovered the botanical garden of
Lorenz Scholz von Rosenau in Breslau.
Cohn was the first to classify
algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
as
plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...
s, and to define what distinguishes them from green plants. His classification of bacteria into four groups based on shape (sphericals, short rods, threads, and spirals) is still in use today. Among other things Cohn is remembered for being the first to show that ''
Bacillus'' can change from a vegetative state to an
endospore state when subjected to an environment deleterious to the vegetative state.
Awards
Cohn was elected a member of numerous institutions and societies, including the Leopold Carolinische Akademie,
Royal Academy of Sciences of Berlin,
Société de biologie de France, the
Royal Microscopic Society of Great Britain, and the
Natural History Society of Boston, among others.
He received the
Leeuwenhoek Medal in 1885, and the
Linnean Medal in 1895. For his efforts leading to the establishment of the Botanical Institute in Breslau in 1888, he received the title of ''
Geheimer Regierungsrat''. On the occasion of his seventieth birthday he was presented with the honorary
freedom of the city of Breslau.
References
External links
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{{DEFAULTSORT:Cohn, Ferdinand
1828 births
1898 deaths
19th-century German botanists
Biologists from the Kingdom of Prussia
19th-century German Jews
Academic staff of the University of Breslau
Foreign members of the Royal Society
German microbiologists
Humboldt University of Berlin alumni
Jewish biologists
Leeuwenhoek Medal winners
Members of the French Academy of Sciences
Members of the Prussian Academy of Sciences
Scientists from the Province of Silesia
Scientists from Wrocław
University of Breslau alumni