Schleiden, Matthias Jakob (1804–1881)

German botanist who identified the fundamental units of living organisms when, in 1838, he announced that the various parts of plants consist of cells or derivatives of cells. This was extended to animals by Theodor Schwann the following year.

Schleiden was born in Hamburg and studied at a number of German universities. He was professor at Jena 1831–62 and at Dorpat, Estonia, 1862–64, after which he returned to Germany.

The existence of cells had been discovered by British physicist Robert Hooke 1665, but Schleiden was the first to recognize their importance. He also noted the role of the nucleus in cell division, and the active movement of intracellular material in plant tissues.