Brown, Robert (1773-1858)

Scottish botanist who in 1827 discovered Brownian motion. As a botanist, his more lasting work was in the field of plant morphology. He was the first to establish the real basis for the distinction between gymnosperms (pines) and angiosperms (flowering plants). On an expedition to Australia 1801-05 Brown collected 4,000 plant species and later classified them using the 'natural' system of Bernard de Jussieu (1699-1777) rather than relying upon the system of Carolus Linnaeus. Brown was born in Montrose, Forfarshire (now Tayside). He studied medicine at Edinburgh. In the late 1790s he was introduced to English botanist Joseph Banks, and served as his librarian 1810-20, after the Australian voyage. The concept of Brownian motion arose from his observation that very fine pollen grains suspended in water move about in a continuously agitated manner. He was able to establish that inorganic materials such as carbon and various metals are equally subject to it, but he could not find the cause of the movement (now explained by kinetic theory). Brown also described the organs and mode of reproduction in orchids. In 1831, he discovered that a small body that is fundamental in the creation of plant tissues occurs regularly in plant cells - he called it a 'nucleus', a name that is still used.