Demerec, Milislav

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(b.Kostajnica. AustriaHungary [now Yugoslavia], 11 January 1895: d. Cold Spring Harbor, New York, 12 April 1966)


The son of Ljudevit Demerec, a schoolteacher and school inspector, and Ljubica Dumbovic Demerec, Demerec graduated from the College of Agriculture at Krizevci in 1916, worked as an adjunct at the Krizevci Experiment Station until 1919, and then came to the United States to commence graduate study with Rollins A. Emerson at Cornell University. After receiving his Ph.D. in 1923, Demerec became a resident investigator in the Department of Genetics of the Carnegie Institution of Washington at Cold Spring Harbor, New York. In 1921 he married Mary Alexander Ziegler; they had two daughters, Rada, who became an anthropologist, and Zlata, who became a microbial geneticist. Demerec was assistant director of the Department of Genetics between 1936 and 1941, acting director between 1941 and 1943, and director between 1943 and 1960. In 1941 he also became director of the adjoining Biological Laboratory of the Long Island Biological Association. Under his administration the two laboratories collaborated closely and became in effect the Cold Spring Harbor Biological Laboratory. Demerec became an American citizen in 1931.

The Biological Laboratory had ample facilities for summer investigators, and it organized the Cold Spring Harbor Symposia in Quantitative Biology. Under Demerec the Biological Laboratory built a permanent staff, and the symposia, previously physiological, shifted largely to genetics and cytogenetics, population genetics and evolution, biochemistry and molecular biology, and the rapidly developing fields of virus and bacterial genetics. Summer courses were established that gained Cold Spring Harbor a worldwide reputation as the place for scientists to learn how to’ do’ bacteriophage genetics (from 1945) or bacterial genetics (from 1955). At Cold Spring Harbor one could meet future Nobel Prize winners and geneticists of international stature. Somehow Demerec found sufficient funds from donors to keep the Cold Spring Harbor laboratory growing in staff and reputation, and constantly breaking new ground.

Demerec provided the stimulus for much of the advance in genetics by means of publications to aid investigators. With his colleague Berwind P. Kaufmann he wrote the Drosophila Guide, which went through eight editions between 1940 and 1969 and was an indispensable aid to work with the fruit flyin high school, college, and university courses. Demerec edited the compendium, The Biology of Drosophila (1950). He started the Drosophila Information Service in 1934, which he edited with Calvin B, Birdges, and which was a prototype of the scientific newsletters that enable investigators using a particular organism to exchange unpublished information, list available genetic stocks, and describe new technical aids. Demerec continued editing the newsletter until 1939. He started the first Drosophila stock center at Cold Spring Harbor, maintaining and distributing desired experimental stocks throughout the world. He founded and edited through its first nine volumes (1947–1958) Advances in Genetics, a series of technical reviews. He supported Birdges in the herculean task of making, at Cold Spring Harbor, his accurate maps of the giant banded salivary chromosomes of Drosophila melanogaster.

Demerec also was deeply involved in the international aspects of organized science. He played a significant role in the organization, program arrangements, and financing of the international congresses of genetics, from the sixth (1932) to the tenth (1958). He was vice president of the Seventh International Genetics Congress (1939) and a member of the Permanent International Committee of the International Genetics Congress from 1939 to 1953. He was a member of both the organizing and the program committees for the Tenth Congress.

In spite of these heavy administrative burdens, Demerec was highly productive in scientific research. His first important studies at Cold Spring Harbor continued his interest in the variegated, or mosaic. genetic characters he had worked on as a graduate student studying Indian corn, or maize. In the 1920’s Demerec discovered frequently mutating genes and mosaic characters in Drosophila virilis, and later in delphiniums. His studies of the effects upon mutation of environmental agents such as temperature and X rays, and of internal conditions such as sex, were classic in their field.

In the 1930’s Demerec shifted his interest to problems of radiation-induced mutation. Using Drosophila melanogaster, he obtained an approximate answer to the question of whether all X-ray-induced lethals are small chromosome deficiencies, and determined the frequency of cell-lethal mutations, that is, mutations lethal to a single cell in a surrounding of normal tissue. He analyzed the differences in spontaneous mutability of genes in different stocks of D. melanogaster and established the existence of mutator genes. His interest in unstable genes led him to explore the “position effects” of genes shifted from euchromatic to heterochromatic portions of the chromosomes. In many of these studies he collaborated with a succession of research assistants, colleagues, and visiting investigators at Cold Spring Harbor.

During World War II Demerec shifted his research to bacteria, first to Escherichia coli and subsequently to Staphylococcus aureus and Salmonella typhimurium. Work also was done on the mold Neurospora crassa. Most important were Demerec’s studies of induced mutations in bacteria that confer specific kinds of resistance to penicillin, Aureomycin, and streptomycin. Not reported until after the war was the success in producing a mutant strain of Penicillium that would grow abundantly when submerged in a vat of nutrient fluid, rather than only when floating on the surface. This achievement multiplied enormously the production of penicillin from a given amount of nutrient. In the 1950’s the mutagenic effects on bacteria of many salts, organic chemicals, and especially carcinogens were detected. The fine structure of the gene and the linkage relationships of the genes of S. typhimurium were the subjects of another classic study, carried forward largely with the collaboration of Demerec’s daughter Zlata and his son-in-law Philip Hartman.

In 1960 Demerec retired as director of the joint Cold Spring Harbor laboratories. Although at first he intended to remain there to do research, unpleasant relations with his successor led Demerec to transfer his experimental work in 1961 to the Brookhaven National Laboratory, where as a senior staff member he continued to investigate problems of mutation, transduction by phage, and linkage in Salmonella. Especially significant was his discovery of the clustering of functionally related genes in the bacterial chromosome, and of the genetic homologies between Salmonella and E. coli. Demerec retired from Brookhaven in 1965 and then assumed a post as research professor of biology at C. W. Post College of Long Island University. He died of a heart attack while organizing his new laboratory.

Among Demerec’s many honors were the presidencies of the Genetics Society of America (1939) and the American Society of Naturalists (1954), as well as membership in the National Academy of Sciences, the American Academy of Arts and Sciences, and the American Philosophical Society. He received the Order of St. Sava from Yugoslavia in 1935, and the Kimber Genetics Gold Medal from the National Academy of Sciences in 1962. He held many visiting appointments and lectureships, and served on the genetics panel of the National Academy of Sciences’ Committee on the Biological Effects of Atomic Radiation, which issued important reports in 1956 and 1960. His influence as organizer, administrator, and investigator was probably unsurpassed in genetics in the period from 1930 to 1960.


For a fuller treatment of the life and work of Demerec, and for a complete bibliography of his publications, see Bentley Glass, “Milislav Demerec,” in Biographical Memoirs. National Academy of Sciences, 42 (1971), 1–27, and A Guide to the Genetics Collections of the American Philosophical Society (1988), 25–30. See also Joseph Fruton, Bio-bibliography of the History of the Biochemical Sciences Since 1800 (Philadelphia, 1982), 159, which lists other biographical references. Primary source material, papers, and 56 volumes of research notes (about 9.500 items in all) are in the Library of the American Philosophical Society, Philadelphia.

Bentley Glass.