Tag Archives: entomologists

Whose Wednesday: David Keilin

by Piter Kehoma Boll

Today we celebrate the birthday of a Russian-British entomologist, David Keilin, whose work had important outcomes not only in entomology, but also in parasitology, biochemistry and even, indirectly, in molecular phylogeny.

Born on March 21, 1887 in Moscow, David Keilin was the son of Polish parents, his father being a small businessman. The family returned to Warsaw, Poland, when Keilin was still very young.

Since childhood, Keilin was a kid of poor health and who suffered from asthma. As a result, he was taught at home by a governess and only started to attend school at the age of 10. From this time until he was 17, he attended the Gorski school and showed an aptitude for mathematics, languages and literature.

After finishing school, he went to the University of Leige in Belgium, where he studied natural sciences, completing the two-year program in a single year. As he continued to have health issues at this time of his life, he was advised not to engage in medical studies, so in 1905 he moved to Paris where he attended philosophy lectures at the College de France and spent a lot of his time reading books at the Bibliotheque St. Genevieve.

One day, after having left a lecture by the philosopher Henri Bergson (1859-1941), Keilin was caught in a heavy rain and, seeking refuge, he ended up in a building that housed the Laboratoire d’Évolution des Êtres Organisés. There, the biologist Maurice Caullery (1868-1958) was giving a lecture and, having to wait the rain to give a break, Keilin watched the lecture and became impressed by it. As a result, he started to attend Caullery’s class three times a week and both became good friends. Caullery eventually offered him a position at the Laboratoire d’Évolution, where he worked as a parasitologist, and convinced him to enroll at the Sorbonne, where Keilin began classes in zoology, botany, embryology and geology.

Keilin published his first paper, on the life cycle of the fly Pollenia rudis, in 1909, and in 1915 he finished his doctorate. Soon after, he was recruted to Cambridge in the United Kingdom as an assistant to American-British bacteriologist George Nuttall (1862-1937) and spent the rest of his career there.

Up until 1920, most of Keilin’s work was descriptive, after which it became more experimental. While studying the life cycle of the horse bot fly, he observed a disappearance of the red color of the larva in later stages. By performing direct-vision spectroscopy on the pigments, he found a four-banded pattern in adult flies which he later also found in other organisms, including other insects, yeasts and even bacteria. By more detailed observations he found out that these pigments were oxidized by atmospheric oxigen, but in its absence were re-reduced. He decided to call this pigments cytochromes, and spent the rest of his career studying this pigments, discovering their function in cellular respiration.


David Keilin in 1931. Author unknown.

Keilin succeeded Nuttall in 1931 and retired in 1965, but continued an active researcher until his death. During his work, Keilin studied several molecules and shed a lot of light on the mechanisms of cellular respiration.

On the afternoon of February 27, 1963, aged 75, Keilin died suddenly after a morning engaged in his usual activities in the laboratory.

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Dead Scientist of the Week. David Keilin. Available at < http://deadscientistoftheweek.blogspot.com.br/2010/03/david-keilin.html>. Access on March 20, 2018.

Dixon, M.; Tate, P. (1966) Obituary Notice: David Keilin, 1887-1963Journal of General Microbiology 45: 159-185.

Erling, N. (2016) Nobel Prizes and Notable Discoveries. 580 pp.

Wikipedia. David Keilin. Available at < https://en.wikipedia.org/wiki/David_Keilin >. Access on March 20, 2018.

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Whose Wednesday: Karl Ernst von Baer

by Piter Kehoma Boll

Hello, folks! So I decided to start one more regular section at our blog. Every Wednesday I’ll bring you a naturalist or other scientist so that you can know a little bit more about those that made biology what it is today. I’ll try to make it about someone whose birthday falls on that day, but I cannot asure that it will work every week, as I (still) don’t know at least one biologist that was born on every day of the year.

But our category will start right now with an Estonian scientist.

Karl Ernst Ritter von Baer, Edler von Huthorn, was born on February 28, 1792, in Piep (or Piibe), Estonia. During his adolescence and early adulthood, he was very unsatisfied with the education he received in his home country and eventually left it to study abroad in Berlin, Vienna and Würzburg. In Würzburg, he met physician Ignaz Döllinger and was introduced by him to the field of embryology, which he embraced gladly.


Portrait of Karl Ernst von Baer made before 1852. Author unknown.

From 1817 to 1834 he was a professor at Königsberg University (which no longer exists, having been closed in 1946 when the city of Königsberg was transfered to the Soviet Union and renamed Kaliningrad). He dedicated most of his research there to embryology, making remarkable discoveries in the field. He discovered the blastula stage of the embryonic development, as well as the notochord. Together with the embryologist Heinz Christian Pander, he described the germ layer theory of development (i.e., the theory that embryos develop from three (or two) germ layers: ectoderm, mesoderm and endoderm). He also stated that the embryo of “higher” forms do not resemble the adults of “lower” forms, but rather the embryos of those lower forms, which contrasts with the more famous theory of Ernst Haeckel that says that the embryo stages recapitulate the previous forms (“ontogeny recapitulates phylogeny”). For such astounding contributions, von Baer is sometimes called the founding father of embryology.

In 1834, von Baer moved to St. Petersburg and joined the St. Petersburg Academy of Sciences. He then kind of let his interest for embryology aside and concentrated in zoology, geography and so on, doing a lot of field research. In 1845, he helped to found the Russian Geographical Society and, in 1859, the Russian Entomological Society, becoming its first president.


Karl Ernst von Baer in 1865, aged 73.

Later in life, von Baer become a leading critic of Charles Darwin, rejecting the idea of natural selection, even though he stated many years before that he believed in the transmutation of species.

Von Baer died on November 28, 1876, in his sleep, aged 84.

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