Robert Brown. Portrait of Robert Brown (1773- 1858), the Scottish botanist who discovered Brown- ian Motion and named the nucleus structure in cells. He discovered Brownian Motion in 1827 when he noticed that microscopic pollen grains move erratically in water. It was later discovered that the pollen was being buffeted by the random movements of molecules in the fluid. In 1831 Brown was the first to note that living cells generally contained a nucleus. He accepted Jussieu's natural system of plant classification, leading to it replacing Linnaeus's artificial sexual system". He also conducted research into the impregnation of plants."