Wiesner, Julius Von

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(b. Tschechen, Moravia [now Czechoslovakia], 20 January 1838; d. Vienna, Austria, 9 October 1916)

plant anatomy, plant physiology.

Wiesner was the youngest of eight children of Karl Wiesner, a shipping agent in Tschechen, and of Rosa Deutsch. Shortly after his birth the family moved to Brno, where Wiesner spent his youth and attended secondary school. He began his higher education at the Technical University of Brno and continued it at the University of Vienna, where he studied botany under E. Fenzl and Franz Unger, chemistry under Anton von Schrötter, physiology under Ernst Brücke and physics under Andreas von Ettingshausen. He received the Ph.D. from Jena in 1860 and a year later qualified as academic lecturer at the Imperial-Royal Polytechnical Institute (nor the Technical University) for Physiological Botany in Vienna, where in 1868 he was appointed associate professor. He became professor of plant physiology at the Forestry Institute of Mariabrunn in 1870 and, three years later, professor of plant anatomy and physiology at the University of Vienna, where he remained active until 1909.

Wiesner was rector of the University of Vienna during the academic year 1898–1899. Many scientific academies and learned societies elected him to membership: Vienna, Berlin, Paris, Munich, Rome, Turin, Göttingen, Uppsala, and Christiania (Oslo). He was awarded honorary doctorates bythe technical universities of Brno and Vienna and by the universities of Uppsala and Glasgow. For many years Wiesner was a member of the Upper House, and when he retired from teaching in 1909. he was elevated to the hereditary nobility.

The Institute of Plant Physiology of the University of Vienna, of which Wiesner became director in 1873, was still located in a private house. Not until the fall of 1885 was it transferred to the newly built university, where it is still located. There Wiesner could bring to bear his talents as organizer and administrator, and the institution soon became known as one ofthe world’s finest and best equipped plant physiology laboratories.

Led by his preference for applied research, Wiesner at first did work intechnical microscopy and plant raw materials. His investigations on the microscopic characteristics of various fibers, on wood types and on how to demonstrate that a substance is wood, on tanning agents and on dyes, as well as on latexes, rubbers, resins, and balsams, were crowned by his integrated treatment of economically valuable plant materials in Die Rohstoffe des Pflanzenreichs (1873).

Wiesner also contributed work of enduring value in plant physiology withhis studies of transpiration, the movements of plant organs, growth, and other phenomena of plant life. For decades he investigated the relationship between plants and light. In Der Lichtgenuss der Pflanzen he summarized his findings on the influence of the intensity and duration of sunlight in natural habitats on the distribution of plants and the development of their organs. Wiesner modified Bunsen and Roscoe’s photographic method of light measurement to make it applicable to the requirements of plant physiology. He then undertook light measurements in Java. Egypt. Norway, andSpitsbergen, as well as in various parts of North America, thus providing the first survey of the light climate of the earth.

Wiesner also made valuable contributions to other fields. By examinationof old Arabic and Central Asian papers, he demonstrated that six hundred years before the Arabs, the Chinese had known how to make paper from rags.

Wiesner had a lifelong interest in problems of natural philosophy. His book Erschaffung, Entstehung, Entwicklung was published a few weeks before his death.


Wiesner published more than 200 articles in various journals. His books are Einleitung in die technische Mikroskopie (Vienna, 1867); Gummiarten, Harze und Balsame (Erlangen, 1869); Die Entstehung des Chloro phylls in der Pflanze (Vienna, 1877); Elemente der wissenschaftlichen Botanik 3 vols. (I. Vienna, 1881; 2nd ed., 1885; 3rd ed., 1890; II, 1884; 2nd ed., 1891; III, 1889; 2nd ed., 1902; 3rd ed., 1913); Die Elementarstruktur und das Wachstum der lebenden Substanz (Vienna, 1892); Die Rohstoffe des Pflanzenreichs, 2 vols. (Leipzig, 1873; I, Möller; 4th ed., by p. Krais and W. Von Brehmer, 1927; 5th ed., by C. von Regel, Weinheim, 1962); Der Lichtgenuss der Pflanzen Leipzig, 1907); and Erschaffung, Entstehung, EntwicfklungLeipzig, 1916).

A complete bibliography follows Hans Molisch’s obituary of Wiesner in Berichte der Deutschen botanischen Gesellschaft, 34 (1916), 71–99.

Richard Biebl

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