Franz Unger (1800-1870)
Franz Unger was an Austrian botanist, biogeographer, and paleontologist who trained in law, medicine, and natural history before being appointed to the faculty of the University of Graz and director of its botanical garden. He was an early adherent of the “cell theory” (attributed to Schleiden and Schwann) that postulated that all cells in organisms are derived from preexisting cells and that such units are the fundamental building blocks of organisms.
Unger’s pre-Darwinian evolutionary views can be found in a series of books published in the 1850s, including Botanische Briefe (1852) which was translated into English Botanical Letters (1853), Versuch einer Geschichte der Pflanzenwelt (1852), and his popular illustrated treatment of the primeval world Die Urwelt in ihren verschiedenen Bildungsperioden (1851; see Rudwick, 1992 for reproductions of illustrations). Unger stressed that just as there was continuity of cells and cell lineage, that organisms gave birth to other organisms, the same is true of species, which must arise from previously existing species (as opposed to miraculous or spontaneous generation). In essence, Unger gave species the attributes of an ontogeny, with a birth, period of development, and finally extinction. Unger also viewed species and varieties as part of a continuum. Ironically, after publication of On the Origin of Species, Unger rejected the mechanism of natural selection, as this would necessitate the evolution of the human mind. Unger was no materialist.
With respect to plants, Unger hypothesized that the origin of plant life could be traced to a single cell: “In short, the cell is not only the starting point of the individual life of the plant, but at the same time the starting point of the life of species and all higher unities; it is indeed likewise the starting point of the whole plant world.” Unger’s understanding of the fossil history of plants was used to argue that “the world of plants also, which is divided into seven great geological periods (including the present one), has gradually developed itself step by step.” Finally, Unger also noted that deviant forms of plants (sports) could give rise to new varieties and that such deviations were not the result of external (environmental) influences, but rather something more fundamental that can “transmute also one species into another.”
For a great article on Unger and his evolutionism, see Gliboff (1998): Evolution, revolution, and reform in Vienna: Franz Unger’s ideas on descent and their post-1848 reception. Journal of the History of Biology 31: 179-209.