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Ernst Hadorn (1902–1976)
ERNST
HADORN
DEVELOPMENTAL
BIOLOGY
53,
iv-vi(l976)
IN MEMORIAM ERNST
HADORN
(1902-1976) Ernst Hadorn, one of the founders of Developmental Biology, died on April 4, 1976, after a severe illness. Ernst Hadorn was born on May 31, 1902 as the son of a farmer in Forst, Switzerland, where the Hadorn family had been living for centuries, and spent his boyhood on the farm in close contact with nature. His great physical and psychological strength and his open-minded direct approach to other people are, at least in part, reflections of this happy childhood. His father sent him to a teachers’ training college in Bern. After obtaining his college degree he became a school teacher in a little village in the Emmental. In 1925 he entered the University of Bern and studied biology with Fritz Baltzer, who was one of the leading developmental biologists at the time. Baltzer was a student of Theodor Boveri, and Hadorn has carried on this great tradition of experimental biology. This relationship is also indicated in the “Intellectual Pedigree” in Sturtevant’s delightful “History of Genetics,” in which the Hadorn-BaltzerBoveri line goes back to Hertwig and Haeckel. Hadorn felt very much obliged to his teacher and later maintained a close friendship with Baltzer. Hadorn’s early work concerned the problem of nuclear versus cytoplasmic influences on the early development of amphibia by means of merogones. Merogones are obtained by fertilizing enucleated eggs with sperm of the same or related species, and to some extent they allow the study of the influence of the maternal egg cytoplasm and the paternal genome on development. After finishing his Ph.D. he became a high school teacher, since in the early thirties there were hardly any posiCopyright All rights
0 1976 by Academic Press, Inc. of reproduction in any form reserved.
tions open at the universities. He continued his experiments in the basement of his home, where he spent all of his spare time. Due to Baltzer’s recommendation, he was awarded a fellowship from the Rockefeller Foundation to spend a year in the United States. Hadorn realized that amphibia did not possess an ideal system for analyzing the genetic control of development and therefore switched to Drosophila. His stay in the United States had a strong impact upon his scientific career. He spent some time at Harvard, Rochester, and at the Marine Biological Laboratory in Woods Hole and his friendship with G. Beadle, B. Ephrussi, and C. Stern dates back to this time. Beadle and Ephrussi had just developed their technique for transplanting imaginal discs, which was used for the study of eye-color mutants. Applying this technique to the analysis of the “lethal giant larvae” mutant, Hadorn discovered that an implanted ring gland induces metamorphosis in mutant larvae and prematurely induces it in normal larvae. This was the first demonstration of an endocrine gland in Diptera and led the way to the understanding of the hormonal control of metamorphosis and the isolation of ecdysone. Although he was offered a position in the states, Hadorn felt that his roots were in Switzerland and decided to go back to Biel and teach at the high school. Finally, in 1939 he was appointed Associate Professor of Experimental Zoology at the University of Zurich, and in 1943 he became the director of the Zoological Institute. In the following years his research centered around the problem of genetic control of development using lethal and eye-color
vi
DEVELOPMENTAL
BIOLOGY
mutants as specific probes. This work culminated in the comprehensive book “Developmental Genetics and Lethal Factors,” first published in 1955, in which he proposed his theories about pleiotropism and the stepwise activation of genes in the course of development. Subsequently, the imaginal discs became his favoured system for studying determination. Transplantation and fate mapping experiments were followed by studies on cell determination in dissociated and reaggregated disc cells. Hadorn was an excellent teacher and attracted many students. His lectures were lively, full of original thoughts, and presented with great enthusiasm. In 1959, J. Brachet, P. Weiss, and Hadorn were the founding Editors of Developmental Biology, An International Journal, the editorial direction of which was subsequently taken over by the American Society for Developmental Biology. From 1962 to 1964 he became Rektor (president) of the University of Zurich. Even in this period when he had to carry an enormous load of administrative work, he still found the time to carry out experiments with his own hands in the laboratory. In fact, his major discovery of transdetermination was made during that period. I remember well the excitement when T. Schlapfer, one of
VOLUME 53, 1976
his graduate students, discovered wing structures in cultures of eye imaginal discs and when Hadorn found the first leg structures in cultures of genital discs. I had the privilege of being Hadorn’s research assistant during this time. During several years, the cultured discs had to be transferred to fresh host flies every two weeks. With great patience, Hadorn injected the implants, which I had dissected from the host flies, into fresh recipients. This perseverance was also one of his outstanding qualities. Hadorn and a number of his graduate students studied transdetermination, providing a detailed description of the phenomenon, but the underlying mechanism still remains obscure. After his retirement, Hadorn continued to be active and used his broad knowledge and understanding of biology to write an excellent textbook, “General Zoology” (“Allgemeine Zoologie”), together with R. Wehner. Right up to the time of his sudden death he was still versatile enough to follow critically the recent developments in the field of biology. With Ernst Hadorn we have lost one of the truly great biologists. WALTER J. GEHRING Biozentrum, University of Basel, Switzerland
HADORN
DEVELOPMENTAL
BIOLOGY
53,
iv-vi(l976)
IN MEMORIAM ERNST
HADORN
(1902-1976) Ernst Hadorn, one of the founders of Developmental Biology, died on April 4, 1976, after a severe illness. Ernst Hadorn was born on May 31, 1902 as the son of a farmer in Forst, Switzerland, where the Hadorn family had been living for centuries, and spent his boyhood on the farm in close contact with nature. His great physical and psychological strength and his open-minded direct approach to other people are, at least in part, reflections of this happy childhood. His father sent him to a teachers’ training college in Bern. After obtaining his college degree he became a school teacher in a little village in the Emmental. In 1925 he entered the University of Bern and studied biology with Fritz Baltzer, who was one of the leading developmental biologists at the time. Baltzer was a student of Theodor Boveri, and Hadorn has carried on this great tradition of experimental biology. This relationship is also indicated in the “Intellectual Pedigree” in Sturtevant’s delightful “History of Genetics,” in which the Hadorn-BaltzerBoveri line goes back to Hertwig and Haeckel. Hadorn felt very much obliged to his teacher and later maintained a close friendship with Baltzer. Hadorn’s early work concerned the problem of nuclear versus cytoplasmic influences on the early development of amphibia by means of merogones. Merogones are obtained by fertilizing enucleated eggs with sperm of the same or related species, and to some extent they allow the study of the influence of the maternal egg cytoplasm and the paternal genome on development. After finishing his Ph.D. he became a high school teacher, since in the early thirties there were hardly any posiCopyright All rights
0 1976 by Academic Press, Inc. of reproduction in any form reserved.
tions open at the universities. He continued his experiments in the basement of his home, where he spent all of his spare time. Due to Baltzer’s recommendation, he was awarded a fellowship from the Rockefeller Foundation to spend a year in the United States. Hadorn realized that amphibia did not possess an ideal system for analyzing the genetic control of development and therefore switched to Drosophila. His stay in the United States had a strong impact upon his scientific career. He spent some time at Harvard, Rochester, and at the Marine Biological Laboratory in Woods Hole and his friendship with G. Beadle, B. Ephrussi, and C. Stern dates back to this time. Beadle and Ephrussi had just developed their technique for transplanting imaginal discs, which was used for the study of eye-color mutants. Applying this technique to the analysis of the “lethal giant larvae” mutant, Hadorn discovered that an implanted ring gland induces metamorphosis in mutant larvae and prematurely induces it in normal larvae. This was the first demonstration of an endocrine gland in Diptera and led the way to the understanding of the hormonal control of metamorphosis and the isolation of ecdysone. Although he was offered a position in the states, Hadorn felt that his roots were in Switzerland and decided to go back to Biel and teach at the high school. Finally, in 1939 he was appointed Associate Professor of Experimental Zoology at the University of Zurich, and in 1943 he became the director of the Zoological Institute. In the following years his research centered around the problem of genetic control of development using lethal and eye-color
vi
DEVELOPMENTAL
BIOLOGY
mutants as specific probes. This work culminated in the comprehensive book “Developmental Genetics and Lethal Factors,” first published in 1955, in which he proposed his theories about pleiotropism and the stepwise activation of genes in the course of development. Subsequently, the imaginal discs became his favoured system for studying determination. Transplantation and fate mapping experiments were followed by studies on cell determination in dissociated and reaggregated disc cells. Hadorn was an excellent teacher and attracted many students. His lectures were lively, full of original thoughts, and presented with great enthusiasm. In 1959, J. Brachet, P. Weiss, and Hadorn were the founding Editors of Developmental Biology, An International Journal, the editorial direction of which was subsequently taken over by the American Society for Developmental Biology. From 1962 to 1964 he became Rektor (president) of the University of Zurich. Even in this period when he had to carry an enormous load of administrative work, he still found the time to carry out experiments with his own hands in the laboratory. In fact, his major discovery of transdetermination was made during that period. I remember well the excitement when T. Schlapfer, one of
VOLUME 53, 1976
his graduate students, discovered wing structures in cultures of eye imaginal discs and when Hadorn found the first leg structures in cultures of genital discs. I had the privilege of being Hadorn’s research assistant during this time. During several years, the cultured discs had to be transferred to fresh host flies every two weeks. With great patience, Hadorn injected the implants, which I had dissected from the host flies, into fresh recipients. This perseverance was also one of his outstanding qualities. Hadorn and a number of his graduate students studied transdetermination, providing a detailed description of the phenomenon, but the underlying mechanism still remains obscure. After his retirement, Hadorn continued to be active and used his broad knowledge and understanding of biology to write an excellent textbook, “General Zoology” (“Allgemeine Zoologie”), together with R. Wehner. Right up to the time of his sudden death he was still versatile enough to follow critically the recent developments in the field of biology. With Ernst Hadorn we have lost one of the truly great biologists. WALTER J. GEHRING Biozentrum, University of Basel, Switzerland