A failed lawyer turned botanist helped establish that every plant is built from cells
Matthias Schleiden trained in law and opened a practice before a deep personal crisis pushed him toward plants. Peering through a microscope, he declared in 1838 that every plant is made of cells, and with Theodor Schwann turned a loose hunch into one of biology's founding principles.
Schleiden was born in Hamburg on 5 April 1804, the son of the city's municipal physician. He finished legal studies in 1827 and set up as a lawyer, but a period of severe depression led him to abandon the profession. He studied natural science at Göttingen and in 1835 moved to Berlin to concentrate on plants, encouraged by his uncle Johann Horkel to look at how plant embryos form.
Microscopic structure became his speciality. As botany professor at Jena he published his Contributions to our Knowledge of Phytogenesis in 1838, arguing that plants are composed entirely of cells. That same year he and Schwann stated that all living organisms are made of cells, raising an informal belief to a principle often compared with atomic theory in chemistry. He also grasped the importance of the nucleus, which the Scottish botanist Robert Brown had found in 1831, and suspected a link to cell division. Later, Rudolf Virchow added that every cell arises from an earlier cell, and Schleiden concluded that an embryonic plant grows from a single cell.
He wrote for the public too. The Plant: A Biography, from 1848, was reprinted six times by 1864 and included a passage accepting the transmutation of species. He became one of the first German biologists to embrace Darwin and has been called a leading German champion of the theory. Under the pen name Ernst he issued two volumes of poetry, in 1858 and 1873, and the American composer Harriet P. Sawyer set one poem to music.
Though neither Jewish nor a historian, he defended Judaism against antisemitism in two books from 1877 and 1878 on Jewish scholarship in the Middle Ages. After teaching at Dorpat from 1863, Schleiden spent his final days in Frankfurt am Main, dying there on 23 June 1881.
Source: Matthias Jakob Schleiden
