(b. Der Gute Amthof, near Leutschach, Austria, 30 November 1800; d. Graz, Austria, 13 February 1870)
The son of a Styrian jurist, Unger received a Gymnasium education at Graz. His father intended that he become a lawyer; but, under the influence of his friend Anton Sauter, Unger turned to medicine. He studied at the universities of Vienna and Prague, qualifying in 1827. After two years at Stockerau as a general practitioner, he became physician to the assize court in Kitzbühel. In 1835 Unger moved to Graz as professor of botany and zoology and as director of the botanical garden at the Johanneum. He received an offer from the University of Vienna in 1849, when a new chair of plant anatomy and physiology was established there. Unger held that post until 1866, when he retired to Graz.
In his own time Unger’s fame rested chiefly on the Grundzüge der Botanik (1843), Which he wrote with Stephen Endlicher. The work contains a description of cell multiplication by division that is based on Unger’s St. Petersburg prize essay (1840) on the structure of the flowering plant stem and his Aphorismen (1838).The Grundzüge made him Schleiden’s first opponent on the question of the origin of cells, Schleiden advocating free cell formation, while Unger confined this mechanism to the early stages in the formation of organs and put forward as its successor cell multiplication by division. Unger maintained his position in this area of botany with Der Anatomie und Physiologie der Pflanzen(1855).
Unger was an evolutionist before 1859. His conception of the succession of species clearly was influenced by Naturphilosophie, but it also was supported by experimental studies of the impact of changes in the conditions of life upon plant variability. These studies, carried out at Kitzbühel, Graz, and Vienna in the 1830’s and 1840’s, led Unger to oppose the popular link between external influences, especially soil conditions, and variability. His views on evolution were presented in a popular form in a series of articles in the local press in Vienna, and subsequently collected in book form as Botanische Briefe (1852). This piece of scientific journalism provoked a violent personal attack upon Unger by the Catholic press. His resignation was prevented by a strong student protest.
Unger’s evolutionary views also found expression in his attempt to reconstruct the botanical features of the landscape in earlier geological eras, in Die Urwelt in ihren verschiedenen Uebergangsperioden (1851). This and other works reflect his deep interest in paleobotany. He was also a pioneer in the study of the early history of cultivated plants as revealed through cultural relics.
Unger also contributed to the understanding of fertilization in the plants. Although at first holding the mistaken belief that antherozoids were infusorians, in 1837 he argued effectively for the identification of these bodies in the mosses as the male gametes. No longer did he regard the production of antherozoids as signaling the conversion of plant into animal.
Among Unger’s students at Vienna was Gregor Mendel. Unger’s involvement in the working out of the cell theory and its application to the fertilization process may well have played a crucial role in equipping Mendel for the cytological interpretation of his breeding experiments.
1. Original Works. A bibliography of Unger’s publications is in A. Reyer’s biography cited below. Unger’s works include Über den Einflusse des Bodens auf die Vertheilung der Gewächse (Vienna, 1836); a series of books on anatomy and physiology: Aphorismen zur Anatomie und Physiologie der Pflanzen (Vienna, 1838), Grundzüge der Anatomie und Physiologie der Pflanzen (Vienna, 1846), and Der Anatomie und Physiologie der Pflanzen (Vienna, 1855); and several books on paleobotany: Synopsis plantarum fossilium (Leipzig,1845);Genera et species plantarum fossilium (Vienna, 1850); Die Urwelt in ihren verschiedenen Bildungsperioden (Vienna, 1851), translated as Ideal Views of the Primitive World in Its Geological and Palaeontological Phases (London, 1863); and Versuch der Geschichte der Pflanzenwelt (Vienna, 1852). Unger’s important prize essay is Über den Bau des Dikotyledonenstammes (St. Petersburg, 1840).
Other works include Grundzüge der Botanik (Vienna, 1843), written with S. Endlicher: “Beiträge zur Lehre von der Bodenstätigkeit gewisser Pflanzen,” in Denkshriften der Akademie der Wissenschaften, 1 (1850), 83–89, written with F. Hruschauer; and Gratz. Ein naturhistorisch-statisch-topographisches Gemählde dieser Stadt und ihrer Umgebungen (Gratz, 1843), written with A. von Muchar, C. Weiglein, and G. F. Schreiner. Unger’s best-known popular work is Botanische Briefe (Vienna, 1852), translated as Botanical Letters to a Friend (London, 1863).
Unger’s papers on botany in relation to cultural history appeared in the Sitzungsberiuchte der Akademie der Wissenschaften in Wien, and all the papers are listed in Reyer’s biography and in the Royal Society Catalogue of Scientific Papers, 6 . p. 87, p. 1137.
Unger’s correspondence with Endlicher is in G. Haberlandt , ed., Briefwechsel zwischen Franz Unger und Stephen Endlicher (Berlin, 1899).
II. Secondary Literature. The standard biography of Unger is A. Reyer, Leben und Werke des Naturhistorikers Dr. Franz Unger (Graz, 1871). Unger’s cytological studies are discussed in Julius Sachs, History of Botany (1530-1860) (Oxford, 1906), 325-329, 336-340; and in J. Lorch, “The Elusive Cambium,” in Archives internationales d’histoire des sciences, 20 (1967), 253–283. The relationship between Unger and Mendel is discussed by R. C. Olby, in “Franz Unger and the Wiener Kirchenzeitung: An Attack on One of Mendel’s Teachers by the Editor of a Catholic Newspaper,” in Folia Mendeliana, no. 2 (1967), 29–37: and in “The Influence of Physiology on Herditary Theories in the Nineteenth Century,” ibid. , no. 6 (1971), 99–103. For an evaluation of some of Unger’s scientific work. see Johanna Enslein, Die wissenschaftgeschichtliche Untersuchung und Wertung der anatomischen, physiologischen und ökologischen Arbeiten von Franz Unger (Vienna, 1956).