Robert Brown discovered and named the cell nucleus in the 19th century. The discovery was made when he was trying to determine why pollen grains moved inconsistently in the water.
The erratic movement of pollen grains was named Brownian motion after Brown's discovery. Brown was a well-respected botanist, and he became the president of the Linnean Society, the world's oldest biological society, in 1849. He made countless and significant contributions to botany field, including collecting and classifying thousands of botanical specimens during an expedition to Australia in 1801. The discoveries Brown made using a microscope are still beneficial in today's research.