Robert Brown, the Cell Nucleus, and the Study of Pollen

Charles Darwin's theory of evolution by natural selection was first presented in the form of a paper read at a meeting of the Linnean Society in London on July 1, 1858. The meeting had been arranged hastily, following Darwin's receipt on June 18 of a paper by Alfred Russel Wallace (1823–1913) setting out an almost identical theory. Meetings of the Linnean Society are arranged months if not years ahead, but Darwin was lucky because there had been a cancellation necessitated by the death on June 10 of the advertised speaker, the Scottish botanist Robert Brown.

At the time of his death Brown was curator of the botanical collections at the British Museum, a large part of which had formerly belonged to Sir Joseph Banks. Brown had been Banks's librarian, and in his will Banks had bequeathed to Brown the full use of his books and specimens for life, but on condition that the collection be stored at the British Museum.

In 1827, the year Banks's material was transferred to the museum, Robert Brown had been studying plant pollen from pinkfairy (Clarkia pulchella). A keen microscopist, Brown had suspended the pollen grains in water to make them easier to observe. He found that the grains moved about ceaselessly in an agitated fashion and that when he repeated the observation using fine grains of carbon and metal those moved in the same way, proving that the motion was not due to any biological process. He described his discovery in 1828 in an article “A brief account of microscopical observations made in the months of June, July and August 1827 on the particles contained in the pollen of plants, and on the general existence of active molecules in organic and inorganic bodies,” published in the Edinburgh New Philosophical Journal. Brown had no idea what caused the movement. Physicists now know that it results from the random movement of molecules, and it is known as Brownian motion.

Brown also studied the anatomy of fossilized plants and plant reproduction. In 1831 while he was investigating plant fertilization, he noticed a small structure that occurred in all plant cells and that played an important part in cell division. He called it a nucleus, and that is the name by which it continues to be known.

Robert Brown was born at Montrose, Scotland, on December 21, 1773, the son of an Episcopalian clergyman. He was educated at Marischal College, Aberdeen, and studied medicine at Edinburgh University, but without obtaining a degree. In 1795 he joined the Fifeshire Regiment of Fencibles as a surgeon's mate with the rank of ensign and almost immediately the regiment was posted to Ireland.

Brown was a hard worker, with a strict routine. Before breakfast he studied German, after breakfast he studied botany, he saw patients for two hours during the afternoon, and unless he was socializing he continued his scientific studies until midnight.

In 1798 Brown was sent to London to find recruits, and while there he was introduced to Banks, who was impressed by him. When, in 1800, Banks was planning a voyage of discovery to Australia he chose Brown to accompany him as a botanist. They sailed on July 18, 1801, on the Investigator, commanded by Captain Matthew Flinders, and reached Australia on December 8. They arrived back in England in October 1805 with specimens of nearly 4,000 species of plants, as well as many zoological specimens. The government paid Brown a salary during the five years he worked on the material. He described 2,200 species, of which 1,700 were previously unknown to science, and Brown named 140 new genera. From 1806 to 1822 Brown worked for the Linnean Society. He was elected a fellow of the Linnean Society in 1822 and was its president from 1849 to 1853. He died in London.