Vocation : Science : Biology

Gustaaf Adolf Frederik Molengraaff (27 February 1860 – 26 March 1942) was a Dutch geologist, biologist and explorer. He became an authority on the geology of South Africa and the Dutch East Indies.
Gustaaf Molengraaff studied mathematics and physics at Leiden University. From 1882 he studied at Utrecht University. As a student he made his first journey overseas when he joined the 1884–1885 expedition to the Dutch Antilles led by Willem Frederik Reinier Suringar and Karl Martin. He became PhD with a thesis on the geology of Sint Eustatius. He studied crystallography in Munich, where he also took the opportunity to study the geology of the Alps nearby.
In 1888 Molengraaff took a job as a teacher at the University of Amsterdam. Before his assignment courses in geology were given by the chemist Jacobus Henricus van 't Hoff. During his assignment in Amsterdam, Molengraaff travelled to South Africa to study gold deposits (1891) and to Borneo (1894) where he explored large parts of the inland. Teaching at Amsterdam was not to his liking, because there were too little materials and students available.
In 1897 Molengraaff became "state geologist" of the Transvaal Republic. His task was to start the geological survey of the Transvaal. While mapping the Transvaal he discovered the Bushveld complex. In 1900 he got involved in the Second Boer War and had to return to the Netherlands. This gave him time to write a report on the geology of the Transvaal, and travel to Celebes, where he (again) studied gold deposits.
Due to his reputation as a geologist he could return to South Africa in 1901 to work as a geological consultant. One of his assignments was to describe the newly found Cullinan diamond for the Central Bank of South Africa. Meanwhile the Boer War still had his attention. One of his ideas was to give each soldier a small tin identity card, which later became practice in armies around the world.
In 1906 he became professor at Delft University and this time he got enough resources and students to make his work successful. The same year he became member of the Royal Netherlands Academy of Arts and Sciences. In 1910-1911 he led a geological expedition to Timor. His research at Delft was mainly on the material collected during that expedition, and on the geology of the Netherlands. In 1922 he was a guide, along with A L Hall, of the Shaler Memorial Expedition to South Africa, organized by Harvard University. On the expedition he met Alexander Du Toit, both geologists were among the (at that time rare) supporters of Alfred Wegeners' continental drift theory.
Molengraaff was a close friend of W. F. Gisolf, who named his youngest son after him but died in a Japanese concentration camp.
Molengraaff retired in 1930.

Marie Pasteur, née Laurent (15 January 1826 in Clermont-Ferrand, France – 28 September 1910 in Paris), was the scientific assistant and co-worker of her spouse, the famous French chemist and bacteriologist Louis Pasteur.

Johannes Cornelis Hendrik de Meijere (1 April 1866, Deventer – 6 November 1947) was a Dutch zoologist and entomologist who specialised in Diptera and Coleoptera.
Prof. dr. Johannes Cornelis Hendrik de Meijere was Rector Magnificus at the University of Amsterdam.

Jean Pierre Mégnin (16 January 1828 – 31 December 1905) was a French army veterinarian and entomologist. He is best known for his work with dogs in the field of cynology. He also contributed to the field of forensic entomology. He led experiments which unveiled the eight distinct waves of insect succession on corpses exposed to air. Similarly, he showed two waves of insect succession on corpses that are buried.

François Émile Maupas (2 July 1842 in Vaudry – 18 October 1916 in Algiers) was a French librarian, protozoologist, cytologist, and botanist. Maupas contributed to ideas on the life cycle and reproduction of the ciliates. He founded the idea, known as the Maupasian life cycle, that some protists had a definite death following sexual reproduction, contrary to contemporary ideas on protists being immortal. He also identified the existence of mating types in ciliates. He developed culture techniques for a number of organisms and described the nematode Caenorhabditis elegans, which has since become a widely used model organism in biological studies.

Louis Alexandre Mangin (8 September 1852, in Paris – 27 January 1937) was a French botanist and mycologist.
In 1873, he became an associate professor at the Lycée de Nancy, followed by a professorship at the Lycée Louis-le-Grand in Paris (1881–1904). During this time frame, he was also a lecturer on natural sciences at the Sorbonne (from 1890). From 1904 to 1931, he was a professor (Chaire de cryptogamie) at the Muséum national d'histoire naturelle, and was director of the museum from 1919 until his retirement in 1931. For several years he was director of the menagerie at the Jardin des Plantes (1920 to 1926).
Mangin was a member of the Académie des sciences, the Académie d'agriculture de France, the Académie des sciences coloniales and the Société mycologique de France.
His early research dealt largely with plant anatomy and physiology; his doctoral thesis involving the adventitious roots of monocotyledons. With Gaston Bonnier (1853–1922), he performed extensive research of plant respiration, transpiration and carbon assimilation. In the early 1890s he is credited with the discovery of callose, a fundamental substance found in the cell membrane of plants.

Louis Charles Émile Lortet (22 August 1836 – 26 December 1909) was a French physician, botanist, zoologist and Egyptologist who was a native of Oullins.
He earned his medical doctorate in 1861, and his degree in natural sciences in 1867. He served as premier doyen at the Faculty of Medicine of Lyon from 1877 until 1906. Also, from 1868 to 1909, he was director of the natural history museum in Lyon.
Lortet is remembered for his scientific and zoological expeditions to the Middle East (Syria, Lebanon and Egypt). He performed studies of mummified animals from the New Kingdom of ancient Egypt, and in 1880 took part in an excavation of a Phoenician necropolis.
Lortet was a member of numerous scientific societies, such as the Société de géographie de Lyon, being a founding member in 1858. Species with the epithet of lorteti are named in his honor; an example being the pufferfish species Carinotetraodon lorteti.