Cohn, Ferdinand

▪ German botanist
born Jan. 24, 1828, Breslau, Silesia, Prussia
died June 25, 1898, Breslau
 German naturalist and botanist known for his studies of algae, bacteria, and fungi. He is considered one of the founders of bacteriology.

      Cohn was born in the ghetto of Breslau, the first of three sons of a Jewish merchant. His father spared no effort in the education of his precocious oldest child, and Ferdinand retained a melancholy recollection of his overly studious childhood. Cohn started his higher studies at the University of Breslau where, as a Jew, he could not be admitted to the candidacy for the doctor's degree. So instead he received his Ph.D. from the more liberal University of Berlin, at the young age of 19.

      In 1850 Cohn was named lecturer at the University of Breslau. He became extraordinary professor there in 1859 and finally became ordinary professor of botany at the university in 1871. In 1866 he founded and in 1872 became the director of the Institute of Plant Physiology at the University of Breslau; this was the first institute of plant physiology in the world.

      Cohn's early research centred on the unicellular algae, the lowest forms of plant life. He applied to these organisms the principle that the phases of growth of microscopic plants could be learned only by observing every stage of their development under the microscope, just as differences in the youthful and adult appearance of an oak or a fern are traced by direct observation. His accounts of the life histories of a number of algae species were of permanent value, and in 1855 he helped to establish the existence of sexual processes in algae, specifically in Sphaeroplea. He also instituted marked reforms in the classification of algae.

      About 1868 Cohn started to study bacteria. From his accurate studies of their morphology, or bodily form, he was among the first to attempt to arrange the different varieties of bacteria into genera and species on a systematic basis. Up to that time, Louis Pasteur and others had been content with a rather arbitrary and confusing system of nomenclature. Cohn based the four groups and six genera of bacteria within his system on basic morphological differences, although he pointed out that morphology alone was an insufficient basis for classification and that differences in biochemical characteristics could also be important.

      In 1870 Cohn founded a new journal entitled Beiträge zur Biologie der Pflanzen (“Contributions to the Biology of Plants”), in which he played such a large part that it came to be known as “Cohn's Beiträge.” Many of the founding papers of bacteriology were to be published in this journal.

      Among Cohn's most striking contributions was his discovery of the formation and germination of spores (called endospores) in certain bacteria, particularly in Bacillus subtilis. He was also the first to note endospores' resistance to high temperatures, and by his observations he was able to refute contemporary experiments that seemed to lend support to the theory of spontaneous generation. Cohn explained the quick reappearance of bacteria in thoroughly boiled flasks of hay and turnip–cheese infusions by speculating that the bacteria within them had formed thermoresistant spores and were thus able to survive the boiling intact, after which they reverted to their normal reproductive stages. He was thus able to refute other bacteriologists' assumptions that all the bacteria in the boiled infusions had been killed by the heat, and he showed the fallacy of their reliance on spontaneous generation as the only remaining explanation.

      In 1876 Robert Koch, who was then unknown but was later to become the founder of medical bacteriology, turned to Cohn for a prepublication appraisal of his work on the cause of anthrax, a disease of cattle, sheep, and, sometimes, of man. Cohn agreed to see the unknown country physician and quickly recognized Koch as “an unsurpassed master of scientific research.” It was in Cohn's Beiträge that Koch published his paper demonstrating that Bacillus anthracis was the causative agent of anthrax, and it was through Cohn's support that Koch was appointed to the Imperial Health Office in Berlin, where he continued his brilliant work.

      During his lifetime Cohn was recognized as the foremost bacteriologist of his day. He is noted for his formulation of the concept that bacteria can be classified into species on the basis of their morphology and physiological characteristics, and for his discovery of the bacterial endospore, an advance that played an important part in the development of techniques of sterilization and in the rejection of the doctrine of spontaneous generation. But perhaps his greatest achievement was his introduction of the strict and systematic observation of the life histories of bacteria, algae, and other microorganisms.

Additional Reading
For Ferdinand Cohn's place in science, see William Bulloch, The History of Bacteriology (1938); and H.A. Lechevalier and M. Solotorovsky, Three Centuries of Microbiology (1965). A second edition of the English translation of Cohn's book, Bacteria: The Smallest of Living Organisms (1939), contains a bibliography of his publications. His wife, Pauline Cohn, wrote his biography, Ferdinand Cohn: Blätter der Erinnerung (1901).

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Universalium. 2010.

Look at other dictionaries:

  • COHN, FERDINAND JULIUS — (1828–1898), German botanist and pioneer bacteriologist. Cohn was born in Breslau, the eldest son of Isaac Cohn, who held the post of Austro Hungarian consul. He joined the faculty of the University of Breslau in 1851 as a lecturer in botany and… …   Encyclopedia of Judaism

  • Cohn,Ferdinand Julius — Cohn (kōn), Ferdinand Julius. 1828 1898. German botanist who is considered the founder of bacteriology. He was the first to recognize bacteria as plants. * * * …   Universalium

  • Cohn , Ferdinand Julius — (1828–1898) German botanist and bacteriologist Cohn, who was born in Breslau (now Wrocław in Poland), was an extremely intelligent child and progressed through school rapidly, being admitted to the philosophy department at Breslau University at… …   Scientists

  • Cohn, Ferdinand (Julius) — (24 ene. 1828, Breslau, Silesia, Prusia–25 jun. 1898, Breslau). Naturalista y botánico alemán, considerado uno de los fundadores de la bacteriología. Obtuvo su Ph.D. en la Universidad de Berlín a la edad de 19 años. Sus primeras investigaciones… …   Enciclopedia Universal

  • Cohn, Ferdinand (Julius) — born Jan. 24, 1828, Breslau, Silesia, Prussia died June 25, 1898, Breslau German naturalist and botanist, considered one of the founders of bacteriology. He received a Ph.D. from the University of Berlin at age 19. His early research centred on… …   Universalium

  • Cohn, Ferdinand Julius — (1828 93)    German botanist and bacteriologist. Born in Breslau, he studied at the universities of Breslau and Berlin. In 1850 he became a lecturer at Breslau University, and later professor. In 1854 he published the first monograph on… …   Dictionary of Jewish Biography

  • Ferdinand Cohn — Ferdinand Julius Cohn. Ferdinand Julius Cohn (* 24. Januar 1828 in Breslau; † 25. Juni 1898 ebenda) war ein deutscher Botaniker und Mikrobiologe. Er gilt neben Robert Koch als einer der Begründer der modernen Bakteriologie. Sein offizielles …   Deutsch Wikipedia

  • Ferdinand Julius Cohn — Ferdinand Julius Cohn. Ferdinand Julius Cohn (* 24. Januar 1828 in Breslau; † 25. Juni 1898 ebenda) war ein deutscher Botaniker und Mikrobiologe. Er gilt neben Robert Koch als einer der Begründer der modernen Bakteriologie. Sein offizielles… …   Deutsch Wikipedia

  • Ferdinand Cohn — Ferdinand Julius Cohn. Ferdinand Julius Cohn, ( Breslau, 24 de enero de 1828 – Breslau, 25 de junio de 1898 ) fue un botánico y bacteriólogo alemán. Contenido …   Wikipedia Español

  • Ferdinand Cohn — Ferdinand Julius Cohn Pour les articles homonymes, voir Cohn. Ferdinand Julius Cohn. Ferdinand Julius Cohn est un botaniste et un microbiologiste allemand, né le …   Wikipédia en Français

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