| Date | Text | |
|---|---|---|
08 Dec 1730
Jan Ingenhousz |
birth Jan Ingenhousz Born 8 Dec 1730; died 7 Sep 1799 at age 68. Dutch-English physician who discovered photosynthesis by identifying that sunlight gave green plants the ability to take in carbon dioxide, fix the carbon, and purified the air (returned oxygen) to the benefit of respiration of animals. Earlier, as a physician, he promoted Edward Jenner's use of inoculation with live smallpox vaccine to induce protection against the disease. Ingenhousz was a diligent experimenter, who studied soils and plant nutrition. He introduced the use of cover slips on microscope slides. He improved phosphorus matches and an apparatus for generating static electricity; investigated Brownian motion and heat conduction in metals, invented a hydrogen-fueled lighter, and mixed an explosive propellant for firing pistols. |
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08 Dec 1730
Johann Hedwig |
birth Johann Hedwig Born 8 Dec 1730; died 18 Feb 1799 at age 68. German botanist who did more than any other scientist to advance the knowledge of mosses (bryology). He dealt with the anatomy, fertilization, and reproduction of mosses and introduced a new method of classification based on the distribution of spores (reproductive bodies). Hedwig was the first to recognize the true organs of reproduction in mosses. He demonstrated the close relationship between mosses and liverworts. He described the development of the spore capsule (sporogonium) bryophytes, and was one of the first to observe, and the first to illustrate, conjugation in the aglae Spirogyra and Chara. Skilled in the use of the microscope, he identified more mosses than any other botanist of his time and produced a series of well-illustrated, informative books on them, illustrated by accurate and beautiful figures, many of which were drawn from highly magnified images. His posthumous Species Muscorum (1801), based on natural groupings, was a landmark in moss taxonomy and has been adopted as the starting point of moss nomenclature. The moss genus Hedwigia is named for him. |
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