Christian Gottfried Ehrenberg

Christian Gottfried Ehrenberg (19 April 1795 – 27 June 1876) was a German naturalist, zoologist, comparative anatomist, geologist, and microscopist. He was one of the most famous and productive scientists of his time.
Microscopic organisms.
Ehrenberg was appointed professor of medicine at Berlin University in 1827. In 1829 he accompanied Alexander von Humboldt through eastern Russia to the Chinese frontier. After his return he began to concentrate his studies on microscopic organisms, which then were not much studied.
For nearly 30 years Ehrenberg examined samples of water, soil, sediment, blowing dust and rock and described thousands of new species, among them well-known flagellates such as Euglena, ciliates such as "Paramecium aurelia" and "Paramecium caudatum", and many fossils, in nearly 400 scientific publications. He was particularly interested in a unicellular group of protists called diatoms, but he also studied, and named, many species of radiolaria, foraminifera and dinoflagellates.
These researches built up our knowledge of the microorganisms of certain geological formations, especially of the chalk, and of the marine and freshwater accumulations. Until Ehrenberg took up the study it was not known that considerable masses of rock were composed of minute forms of animals or plants. He also demonstrated that the phosphorescence of the sea was due to organisms.
He was a member of the Royal Swedish Academy of Sciences from 1836 and a foreign member of the Royal Society of London from 1837. In 1839, he won the Wollaston Medal, the highest award granted by the Geological Society of London. He continued until late in life to investigate the microscopic organisms of the deep sea and of various geological formations. He died in Berlin on 27 June 1876.
Legacy.
After his death in 1876, his collections of microscopic organisms were deposited in the Humboldt Museum at the University of Berlin. The "Ehrenberg Collection" includes 40,000 microscope preparations, 5,000 raw samples, 3,000 pencil and ink drawings, and nearly 1,000 letters of correspondence. His collection of scorpions, and other arachnids from the Middle East, is also held in the Berlin Museum.