SCHWENDENER, SIMON

(b. Buchs, St. Gallen, Switzerland, 10 February 1829; d. Berlin, Germany, 27 May 1919)

plant anatomy.

Schwendener was the son of a farmer; he himself worked on his grandfather’s farm during summer vacations from school. His father wished him to become a teacher, so in 1847 Schwendener began to prepare himself for this career, although he had little inclination for it. From 1849 to 1850 he studied science at the Academy of Geneva. His father could not afford to allow him to attend the University of Zurich for further study, as he had planned, and Schwendener then accepted a teaching position Wädenswil. In 1853 his grandfather died and left him a small legacy, which he employed to support himself at the university. He graduated from the University of Zurich in 1854 and was awarded the Ph.D., summa cum laude, in 1856.

Schwendener’s Ph. D. thesis, Ueber die periodische Ercheinungen der Natur, insbesondere der Pflanzenwelt, was inspired by Candolle and finished under the direction of Oswald Heer. Another early—and lasting—influence on Schwendener’s work was that of Carl Naegeli, whose Zurich lecturers Schwendener had attended. Both Naegeli and Schwendener were interested in plant morphology and ontogeny, and Schwendener attracted Naegeli’s attention while attending his courses at the Zurich Eidgenössische Technische Hochschule. As a result, when Naegeli was later, in 1857. appointed professor at the University of Munich, he invited Schwendener to be his assistant, thus invited a close collaboration. Their two-volume work Das Mikroskop (published in 1865–1867) represented three years’ mutual effort; in it Naegeli and Schwendener not only demonstrated a number of details of plant anatomy but also set out the principles that Abbe used in his optical work. Schwendener also did independent research on lichens, and published the first of his several works on that subject in 1860, the same year in which he became Privatdozent.

In 1967 Schwendener returned to Switzerland to take up an appointment as professor ordinarius and director of the botanic garden at the Universities of Basel. He here continued the work on lichens that culminated in his Die Algentypen der Flechtengoidien. Programm für die Rektoratsfeier der Universität, published in 1869. In this book Schwendener first stated that lichens are a composite of algae and fungi (later termed “symbiosis” by De Bary and confirmed by the work of Bornet and stahl). In support of his thesis. Schwendener offered a considerable amount of histological evidence.

Schwendener then began to examine the mechanical properties of plants, seeking an analogue in plants to the animal skeleton or to the materials used in constructing a bridge. He found that the principles of mechincs govern the structure of the stems of plants, with maximum rigidity resulting from minimum materials; he presented his findings in Das mechanische Prinzip im anatomischen Bau der Monocotylen, in which, however, he gave no account of the causal development of the structures that he described. The book, published in 1874, was received unenthusiastically by his fellow botanists.

At Basel Schwendener worked in comparitive isolation and taught only a few students; he was therefore happy to accept an appointment in 1877 to succeed Wilhelm Hofmeister at Tübingen. Here he studied phyllotaxy, again applying mechanical principles. Hofmeister had been the first to refute the spiral theory of leaf development, stating that each point on the growing region of a stem is a potential leaf and adding that new leaves occur within the largest gaps between existing ones. Schwendener went on to demonstrate, using mechanical models, that leaf arrangement was the result of displacement by contact between leaf primordia; his theory was at first fully accepted, then attacked. It remains an important one in the development of the theory of phyllotaxy, and was stated in Mechanische Theorie der Blattstellumgen, published in 1878, the same year that Schwendener went to Berlin to succeed Alexander Braun.

Schwendener stayed in Berlin for thirty-one years, during which time he taught a great number of students and wrote articles in defense of his theory of phyllotaxy and on the movement of fluids in plants, the structure and mechanics of stomata, the theory of descent in botany, and torsion in plants. He was elected to the Berlin Academy of sciences in 1880 and in 1882 was one of the founders of the Deutsche Botanische Gesellschaft. He served as rector of the university from 1887 and retired in 1909. He was, in addition, an honorary member of a number of foreign scientific societies.

Schwendener never married. He was interested in the arts and in literature, and composed several poems. Music, however, he found “a rather disagreeable noise.”

BIBLIOGRAPHY

I. Original Works. Schwendener’s most important writings are his dissertation, Ueber die periodische Erscheinungen der Natur, insbesondere der Pflanzenwelt (Zurich, 1856); Das Mikroskop, 2 vols. (Leipzig, 1865–1867), written with Carl Naegeli; Die Algentypen der Flechtengonidien. Programm für die Rektoratsfeier der Universitat (Basel, 1869); Das mechanische Prinzip im anatomischen Bau der Monocotylen (Leipzig, 1874); and Mechanische Thereio der Blattstellungen (Leipzig, 1878). A number of the number of his work at Berlin are collected in Gesammelte botanische Abhandlungen (Berlin, 1898).

II. Secondary Literature. A short autobiography, written in 1900, and a bibliography are included in A. Zimmermann, “Simon Schwendener,” in Berichte der Deutschen botanischen Gesellschaft, 40 (1922), 53–76. A detailed biography is G. Haberlandt, ibid., 47 (1929), 1–20.

A. P. M. Sanders