NILSSON-EHLE, HERMAN

(b. Skurup, Sweden, 12 February 1873; dLund, Sweden, 29 December 1949)

genetics, plant breeding.

Nilsson-Ehle was the son of Nils Nilsson, a farmer, and his wife, Elin. After first studying in Malmö, he enrolled in 1891 at the University of Lund, where he received the candidate’s degree in 1894, the licentiate degree in 1901, and the Ph. D. in 1909. He began his scientific research in 1894, at first concentrating on plant taxonomy and plant physiology. In 1900 he became an assistant at the Swedish Seed Association in Svalöf (near Lund), and thereafter devoted himself to the new science of genetics and its practical applications in plant breeding.

Nilsson-Ehle realized the fundamental importance of Mendel’s principles of heredity, which had just been rediscovered, and he was especially impressed by Mendel’s clarification of the mechanism of genetic recombination. Nilsson-Ehle was the first to demonstrate that economically important properties in cultivated plants are inherited according to Mendel’s laws and may be recombined in a specific way. In a now-classic paper of 1906 he recommended artificial crosses as the best method of obtaining a recombination of various desirable properties. He cited a series of examples from his own experience and pointed out that part of the offspring of experimentally produced hybrids combined the valuable properties of the parents. At the same time he obtained, as expected, other offspring which represented a combination of the undesirable properties of the parents.

In three papers published in 1908–1911 Nilsson-Ehle demonstrated that quantitative characters (size, earliness, resistance to disease) are inherited in the same Mendelian way as the qualitative characters (differences in flower color, etc.) with which Mendel and the early Mendelists had been working. As a rule, however, the quantitative characters were found to be conditioned by a relatively high number of polymeric (or multiple) genes. After recombination these genes may give rise to numerous quantitative gradations of the characters involved in the crosses. This finding was a very important contribution to the development of basic genetics and a solid basis for its practical application to plant breeding.

In 1915 Nilsson-Ehle was appointed to the chair of physiological botany at the University of Lund. Two years later he moved to the chair of genetics. From 1925 until his retirement in 1939 Nilsson-Ehle was director of the Swedish Seed Association. During this period as an active administrator, he encouraged the development of new fields of research and in 1931 organized a new department for chromosome investigations and the production of new types of polyploid cultivated plants. He realized that induced mutations would be important in plant breeding, and advocated mutation research.

As professor emeritus, Nilsson-Ehle became actively interested in forestry and horticulture, and he was helpful in the founding and development of organizations which sought to improve the stock for forests and orchards through breeding.

Nilsson-Ehle was a member of many academies and received several honorary doctorates. His life was marked by a cyclical mental state: periods of ill health, extraordinary activity, deep depression, and great optimism. He was a fascinating combination of creative fantasy and sober realism; and he combined a farmer’s intimate practical knowledge of soil and crops with the theoretical education and logical acumen of a university professor. Moreover, he was talented musically and often entertained himself and his guests at the piano. He was married and had a daughter and two sons.

BIBLIOGRAPHY

I. Original Works. Among Nilsson-Ehle’s numerous publications the following ones are of especial importance: “Einige Ergebnisse von Kreuzungen bei Hafer und Weizen,” in Botaniska notiser (1908), 257–294; “Kreuzungs-untersuchungen an Hafer und Weizen,” in Acta Universitatis lundensis, n.s. 2, 5 , no. 2 (1909), 1–122; 7 , no. 6 (1911), 1–84; and “Mendélisme et acclimatation,” in IV^e Conférence international génétique Paris (Paris, 1911), 1–22.

II. Secondary Literature. See A. Müntzing, “Lebensbeschreibung von H. Nilsson-Ehle,” in Zeitschrift für Pflanzenzüchtung, 29 , no. 1 (1950), 110–114. In Sveriges utsädesförenings tidskrift (1950), no. 1, there are articles in Swedish about Nilsson-Ehle and his importance for the development of genetics and plant breeding. See also A. Müntzing, “Minnesteckning över Professor H. Nilsson-Ehle,” in Kungliga Fysiografiska Sällskapets förhandlingar, 20 (1950), 1–7; Å. Gustafsson, “Herman Nilsson-Ehle, minnesteckning,” in Levnadsteckningar över Kungliga Svenska Vetenskapsakademiens ledamöter, 175 (1971), 279–293; A. Müntzing, “Om aktualiteten av Herman Nilsson-Ehles teoretiska forskning,” in Sveriges Utsädesförenings tidskrift (1973), no. 2–3, 159–168; and E. Åkerberg, “Om aktualiteten i Herman Nilsson-Ehles insatser i vaxtförädling och jordbruksforskning,” ibid., 169–178.

Arne Müntzing