Hensen, (Christian Andreas) Victor

(b. Schleswig, Germany, 10 February 1835; d. Kiel, Germany , 5 April 1924)

physiology, marine biology.

Hensen was the son of Hans Hensen, director of the school for the deaf and dumb at Schleswig, and his second wife, Henriette Caroline Amalie Suadicani, the daughter of the court physician Carl Ferdinand Suadicani, who had founded the lunatic asylum at Schleswig. From the two marriages of his father Hensen had eight sisters and six brothers.

From 1845 to 1850 Hensen attended the school attached to the cathedral of Schleswig, then the grammar school at Glückstadt (Holstein), where he passed the final examination in 1854. His attainments as a pupil are said to have been only mediocre. He next studied medicine for five semesters at Würzburg (under Scherer, Kölliker, Virchow) from 1854 to 1856. In Scherer’s laboratory Hensen verified Claude Bernard’s data on the glycogen content of the liver. He next studied for two semesters at Berlin, then in 1857–1858 at Kiel, where he passed his final examination. His sixteen-page thesis, written when he was working as a doctor in the lunatic asylum at Schleswig, deals with the possible diagnostic relationship between epilepsy and urinary secretion (1859). Soon afterward Hensen became prosector at the Institute of Anatomy at Kiel. Also in 1859 he qualified there as a lecturer in anatomy and histology. In 1864 he was appointed successor to Peter Ludwig Panum as associate professor of physiology and director of the physiology laboratory at Kiel. In 1868 he became full professor of physiology. In 1870 Hensen married Andrea Katharina Friederike Seestern-Pauly. They had two sons and two daughters. Hensen retired at the age of seventy-six. The most notable of his students in physiology were Paul Höber, Hans Winterstein, and Hans Piper.

Hensen worked mainly in physiology and marine biology. In physiology he preferred the histophysiological method and, using it, settled essential questions regarding the basic conditions for hearing and sight. In 1863 he investigated the decapod hearing organ and the morphology of the human cochlea, describing what are now called Hensen’s supporting cells and Hensen’s duct. He identified the fibers of the basal membrane in the cochlea as resonant corpuscles capable of vibrating. He also proved that these fibers, rather than decreasing, increase in length from base to tip of the cochlea. Hensen investigated the organ of hearing in the forelegs of grasshoppers and also in the fishes (1904). In addition he studied the structure of the cephalopod eye (1865) and the dispersion of cones in the center of the human retina. With J. C. Voelckers he histologically and experimentally investigated the nervous system for accommodation, puncturing the ciliary muscle laterally with the point of a needle. If there is accommodation, the needle moves forward. He described the light “Hensenian zone” in the Q section of the skeletal muscle fibers. In the field of embryology he observed, among other things, the formation of a torus at the beginning of the primitive furrow, or Hensen’s knot (1876). He wrote lengthy summaries on the physiology of hearing (1880, 1902) and on propagation (1881). In 1878 he assumed the direction of a new institute of physiology at Kiel.

Hensen’s second major area, in which he had worked as an amateur since 1863, was marine biology, that is, the investigation of the fauna of the oceans, both the microscopic plankton—a term he coined—and fishes. He developed quantitative methods for determining the amount of commercially useful fish along the coasts, thus laying the foundation for the calculation of the profitability of fisheries. About 1887 he began far-ranging plankton studies, especially quantitative investigations, using a dragnet he had invented. He calculated the quantity of plankton at various depths and in various oceans. For this purpose Hensen organized and led large plankton expeditions. He was a member, and later president, of the Prussian Commission for the Exploration of the German Waters at Kiel. He may be regarded as the originator of quantitative marine research.

Hensen was for several years dean of the Faculty of Medicine and several times was rector of the University of Kiel. He was honorary doctor of Kiel, a member of the Leopoldine Academy, and a corresponding member of the Bavarian and Prussian academies of science.

BIBLIOGRAPHY

I. Original Works. Hensen’s major publications in physiology are “Über die Zuckerbildung in der Leber,” in Verhandlungen der Physikalisch-medizinischen Gesellschaft zu Würzburg, 7 (1857). 219; “Studien üher das Gehororgan der Dekapoden,” in Zeitschrift für wissenschaftliche Zoologie, 13 (1863). 319–412; “Zur Morphologic der Schnecke des Menschcn und der Säugethiere,” ibid., 481–512; “Ueber das Gehörorgan von Locusta,” ibid. 16 (1866), 190–207; “Ueber das Sehen in der Fovea centralis,” in Virchows Archiv für pathologische Anatomie, 39 (1867), 475–492; Experimentaluntersuchung üer den Mechanismus der Accommodation (Kiel, 1868), written with J. C. Voelckers; “Ueber den Ursprung der Accommodanonsnerven.,” in Albrecht v. Graefes Archiv für Ophthalmologic, 24 (1878). 1-26, written with J. C. Voelckers; “Ueber die Accommodationsbewegung im menschlichen Ohr,” in Pflügers Archiv für die gesamte Physiologie, 87 (1901), 355–360; and “Die Empfindungsarten des Schalls,” ibid., 119 (1907). 249–294.

His main writings on marine biology are “Beftreffend den Fischfang auf der Expedition,” in Jahresbericht der Kommission zur wissenschaftlichen Untersuchung der deutschen Meere in Kiel für das Jahr 1871 (1873), pp. 155–159; “Resultate der statistischen Beobaclmmgen über die Fischerei an den deutschen Küsten,” ibid. 1874–1876 (1878), 133–171; “Ueber die Bestimmung des Planktons oder des im Meere treibenden Materials an Pflanzen and Thieren.” ibid., 1882–1886 (1887), pp. 1–107, with four plates and a list of the specimens collected; “Einige Ergebnisse der Plankton-Expedition der Humboldt-Stiftung. Vorgelegt von E. du Bois-Reymond,” in Sitzungsberichte der Preussischen Akademie der Wissenschaften zu Berlin, 1 (1890), 243–253; Ergebnisse der in dem Atlantischen Ocean von Mitte Juli bis Anfang November 1889 ausgeführten Plankton-Expedition der Humboldt-Stiftung...” (Kiel-Leipzig. 1892); “Das Plankton der üstlichen Ostee und des Stettiner Haffs,” in Bericht der Kommission zur wissenschaftlichen Untersuchung der deutschen Meere in Kiel fur die Jahre 1887–1891 (1893), pp. 103–137; “Die Nordsee-Expedition 1895 des Deutschen SeefischereiVereins. Über die Eimenge der im Winter laichenden Fische,” in Wissenschaftlichc Meeresuntersuchungen. n.s. 2 , no. 2 (1897). 1–97, written with Carl Apstein: “Über die quantitative Bestimmung der kleineren Planktonoganismen,” ibid., n.s. 5 (1901), 67–81; “Über quantitative Bestimmungen des “Auftriebs,” in Mitteilungen für den Vercin Schleswig-Holsieinischer Aerzte10 , no. 7 (1885); and “Die Methodik der Plankton-Untersuchung,” in E. Abderhalden, ed., Handhuch der biochemischen Arbeitsmethoden. V, pt. 1 (Vienna, 1911), 637–658.

II. Secondary Literature. The only good biography is R üdiger Porep,Der Physiologe und Planktonforscher Victor Hensen (1835–1924). Sein Leben und sein Werk, no. 9 in the series Kieler Beiträge zur Geschichte der Medizin und der Pharmazie (Neümtinster, 1970), with numerous illustrations and good bibliography. There are obituaries by Karl Brandt in Berichte der Deutschen wissenschaftlichen Kommission für Meeresforschung, n.s. 1 (1925), vii-x; and J. Reibisch, in Archiv für llydrohiologie, 16 (1926). i-xiv, with portrait.

K. E. Rothschuh