Ferdinand Julius Cohn (24 January 1828 – 25 June 1898) was a German

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

. He is one of the founders of modern

bacteriology Bacteriology is the branch and specialty of biology that studies the Morphology (biology), morphology, ecology, genetics and biochemistry of bacteria as well as many other aspects related to them. This subdivision of microbiology involves the iden ...

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 Prussia (; ; Old Prussian: ''Prūsija'') was a German state centred on the North European Plain that originated from the 1525 secularization of the Prussian part of the State of the Teutonic Order. For centuries, the House of Hohenzoll ...

Province of Silesia The Province of Silesia (; ; ) was a province of Prussia from 1815 to 1919. The Silesia region was part of the Prussian realm since 1742 and established as an official province in 1815, then became part of the German Empire in 1871. In 1919, as ...

(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 A child prodigy is, technically, a child under the age of 10 who produces meaningful work in some domain at the level of an adult expert. The term is also applied more broadly to describe young people who are extraordinarily talented in some f ...

, 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 The Humboldt University of Berlin (, abbreviated HU Berlin) is a public research university in the central borough of Mitte in Berlin, Germany. The university was established by Frederick William III on the initiative of Wilhelm von Humbol ...

, 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 ''Privatdozent'' (for men) or ''Privatdozentin'' (for women), abbreviated PD, P.D. or Priv.-Doz., is an academic title conferred at some European universities, especially in German-speaking countries, to someone who holds certain formal qualifi ...

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 ''Volvox'' is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. ''Volvox'' species form spherical colonies of up to 50,000 cells, and for this reason they are sometimes called globe algae. First reported by Antonie van L ...

''. 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 ...

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 ''Bacillus'', from Latin "bacillus", meaning "little staff, wand", is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-sh ...

'' can change from a vegetative state to an

endospore An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. The name "endospore" is suggestive of a spore or seed-like form (''endo'' means 'within'), but it is not a true spore (i.e., not ...

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 The Leeuwenhoek Medal, established in 1875 by the Royal Netherlands Academy of Arts and Sciences (KNAW), in honor of the 17th- and 18th-century microscopist Antoni van Leeuwenhoek, is granted every ten years to the scientist judged to have mad ...

in 1885, and the

Linnean Medal The Linnean Medal of the Linnean Society of London was established in 1888, and is awarded annually to alternately a botanist or a zoologist or (as has been common since 1958) to one of each in the same year. The medal was of gold until 1976, and ...

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

* * {{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