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Braun, Alexander Carl Heinrich

Braun, Alexander Carl Heinrich

(b Regensburg, Germany, 10 May 1805; d. Berlin, Germany, 29 March 1877)

botany, philosophy.

For more than twenty-five years Braun was professor of botany and director of the botanical gardens at the University of Berlin, and during his lifetime was the most highly regarded botanist of the Naturphilosoph school. His father, also named Alexander, was a civil servant with scientific interests ranging over mineralogy, physics, and astronomy; his mother, Henriette Mayer, was the daughter of a mathematics professor and former priest. Braun himself married twice. In 1835 he married Mathilde Zimmer, who died in 1843 after the birth of their sixth child. Five children survived to adulthood; two of the daughters from this marriage married the German botanists Robert Caspary and Georg Mettenius. In 1844 Braun married Adele Messmer, who bore him five more children, four surviving toe adulthood. She died just a few months after her husband.

Braun grew up in Karlsruhe in Baden, surrounded by the natural beauty of the Schwarzwald area, and his interest in natural history and botany developed at a very early age. After private tutoring, in 1816 he entered the Karlsruhe Lyceum, where he was still a student when he published his first paper at the age of sixteen. While still a youth Braun also discovered several new species of cryptograms that now bear his name: Chara braunii, Orthorichum braunii, and Aspidium braunii. In 1824 he enrolled at the University of Heidelberg, and in compliance with his father’s wishes, neglected the liberal arts in order to take up the study of medicine. Medicine was soon pushed into the background, however, as his abiding interest in botany took pride of place. At Heidelberg he became intimate friends with Carl Friedrich Schimper and Louis Agassiz. Braun and Agassiz became inseparable friends, and Agassiz eventually married Braun’s sister, Silly. In 1827 Braun and Agassiz went to the University of Munich, attracted, especially by the fame of the Naturphilosophen Oken and Schelling, and in 1829 both went on to Tübingen, where they received their doctorates in that same year.

After four more years of study and travel, including an eventful stay in Paris, Braun accepted a position as teacher of botany and zoology at the newly instituted polytechnic school in Karlsruhe. He remained there until 1846, when he accepted the chair of botany at Freiburg im Breisgau. In 1849 he was elected prorector of the Freiburg Hochschule, and his diplomatic leadership during the Baden revolution did much to keep the school free from political strife. In 1850 Justus von Liebig persuaded Braun to move to Giessen, but he had hardly established residence there before he was offered a position at the prestigious University of Berlin. After some hesitation, Braun accepted the call to the big city in 1851, and he remained there the rest of his life.

Braun made his early reputation in botanical circles by his work on the arrangement of leaves. With his old Heidelberg friend Carl Schimper, Braun established the doctrine of spiral phyllotaxis, according to which growth in a stem has an upward direction in a spiral line such that the leaves are arranged on the stem according to fixed geometrical rules. Most anomalies were accounted for by a formula expressed as a simple continuous fraction. Between 1830 and 1835, Braun and Schimper each published articles introducing and explicating the doctrine, and their friendship was interrupted by Schimper’s rather bellicose claim that he deserved full credit for the ory. Years later, a reconciliation was achieved. Braun, in particular, extended the ory between 1840 and 1860.

The Schimper-Braun theory focused attention on the important question of the relative positions of plant organs and inspired much of the detailed work of the opposing school of “genetic morphologists,” such as Wilhelm Hofmeister, who claimed that the developmental history of plants proved the ory erroneous. Numerous exceptions to the rule certainly did exist, but it served as a roughly valid description of the arrangement of leaves on adult plants, and under its influence the morphological examination and comparison of plants, inflorescences, and vegetative scgoots reached unprecedented completeness.

Bbraun’s most important single work was Betrachtungen über die Erscheinung der Verjüngung in der Natur, written while he was at Freiburg and originally delivered as the prorectorial address for 1849; its publication was delayed until 1851 by Braun’s call to Giessen and by the Baden revolution. Braun’s chief object in this volume is to show that the phenomenon of “rejuvenescnce” distinguishes the organic realm from the inorganic. His diffuse concept of rejuvenescence was an extension of Goethe’s doctrine of metamorphosis and included a consideration of development history, reproduction, and the dissolution of formed structures. More significant than his particular object, however, were Braun’s contributions to the morphology of plants, to the biology of freshwater algae, and especially to a reconstruction of the cell theory. In this last area, his investigation of algae swarm-spores led him to oppose Schleiden and Schwann’s emphasis in the cell wall, and to insist instead that the cell contents were the site of all the physiological activities of the cell. In passages remarkable for the beauty of their language, Braun suggested dramatically that the cell wall was in fact the structure that entombed the true life of the cell, and that could eventually destroy that life by interfering with “rejuvenescence”.

It is clear from Braun’s other important general work, “Das Individuum der Pflanze in seinem Verhältnisse zur Species” (1853), that he believed in the transmutation of species, but he insisted that the process was teleological. He objected strongly to Darwin’s principle of natural selection and to any “mechanistic” explanations that substituted blind external forces for inner direction and purpose. Braun’s general iuterpretations were always colored by his Naturphilosophie, and his work may have exerted less influence than it deserved because he was so obviously and genuinely a Naturphilosoph at a time when that mode of looking at nature was becoming unfashionable.

While at Berlin, Braun had among his pupils Anton De Bary and A. W. Eichler, his successor, who extended the natural system of classification developed by Braun for the ordering of the university’s botanical gardens. In 1879 a bust of Braun was unveiled and placed in the botanical gardens.


1. Original Works. The Schimper–Braun theory of phyllotaxis was developed primarily in the following series of papers: Carl Schimper, “Beschreibung des Symphytum Zeyheri und seiner zwei deutschen Verwandten,” in Magazin für Pharmacie von Geiger, 3 (1830); Braun, “Vergleichende Untersuchung über die Ordnung der Schuppen an den Tannenzapfen, als Einleitung zur Untersuchung der Blattstellung überhaupt”, in Nova acta Academiae Caeserae Leopoldino Carolinae Germanicae naturae curiosorum, 15 (1831), 195–402; and Braun, “Dr. Carl Schimper’s Vortäge über die Moglichkeit eines wissenschafillchen Verständniss der Blasttstellung”, in Flora, oder allgemeine botanische Zeitung (Regensburg), 18 (1835), 145–192. See also report of the meeting of 20 Sept. 1834, ibid., 7–8. For Braun’s reasonableness on the question of priority, see his “Nachträgliche Erläuterungen zu meinem Aufsatz in Nr. 10, 11, und 12 der ‘Flora’; Laufemdem Jahres über Dr. Schimper’ Vorträge”, ibid., 737–746; Schimper’s intemperate reply is ibid., 748–758.

Braun’s most important general works were Betrachtungen über die Erscheinung der Verjüngung in der Natur, insbesondere in der Lebens- und Bildungsgeschichte de Pflanze… (Leipzig, 1851), translated by Arthur Henfrey, in Ray Society Botanical and Physiological Memoirs (1853), vii–xxvi, 1–341; and “Das individuum der Pflanze in seiner Verhältnisse zur Species, Generationsfolge, Generationswechsel und Generationstheilung der Pflanze,“in Abhandlungen der Kö;niglichen Akademie der Wissenschaften Berlin (Physikalische Klasse) (1853), 19–122, rranslated by Charles Francis Stone, in The American Journal of Science and Arts (Silliman’s Journal), 2nd ser., 19 (1855), 297–318; 20 (1855), 181–200; and 21 (1856), 58–79.

For Braun’s contributions in the area of systematics, see Paul F. A Ascherson, Flora der Privinz Brandenburg… (Nebst einer Übersicht des natürlichen Pflanzensystems nach A. Braun) (Berlin, 1864); and A. W. Eichler, Blüthendiagramme, 2 vols. (Leipzig, 1875–1878), passim (esp. 1, 3, 9, 11, 14– 30), Most of Braun’s scientific papers are listed in the Royal Society Catalogue of Scientific Papers (1, 582– 585; VII, 248; IX, 333–334). Braun left behind an extensive manuscript collectionm that the Berlin Royal Academy of Sciences acquired in 1879 and turned over to the Royal Herbarium for safekeeping.

II. Secondary Literature. Of the existing sketches of Braun’s life and work, those written by his daughter Cecilie, though uncritical, are the most interesting because they are illuminated by Braun’s personal letters. See Cecilie Mettenius, “Alexander Braun”, in Leopoldina, 13 (1877), 50–60, 66–72; and Alexander Braun’s Leben nach seunem handschriftlichen Nachlass dargestellt… (Berlin, 1882). The best source for estimating Braun’s place in the history of botany is Ferdinand G. Julius von Sachs, Geschichte der Botanik vom 16. Jahrlimdero bis 1860 (Munich, 1875), pp.185–195. It should be pointed out, however, that Sachs is unsympathetic toward Braun’s general mode of viewing nature. For other sketches of Braun’s life and work, see Robert Caspary, in Flora, n.s 25 (1877), 433–442, 449–457, 465–471, 497–507, 513–519; A.W. Eichler, in Leopoldina, 15 (1879), 163–165; Allgemeine deutsche Biographie, XLVII (1903), 186–193; and Neue deutsche Biographie, II (1953), 548.

Gerald L. Geison

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