Obituaries

Barbara McClintock, the pioneering geneticist who was recognized as a major directing force in 20th-century science, died September 2 in Huntington, N.Y., at the age of 90. Until her death, the Nobel Prize-winning McClintock conducted her research at the Carnegie Institution's Department of Genetics in Cold Spring Harbor, N.Y. She had joined the Cold Spring Harbor lab's staff in 1941. She won the Nobel in 1983 for her discovery of transposable elements, or "jumping genes," in a study of varying color patterns in maize kernels. McClintock spawned the revolutionary idea that small segments of DNA could move around the chromosomes ("Chromosome organizations and genic expression," Cold Spring Harbor Symposium on Quantitative Biology, 16:13-47, 1951).

James Watson and Francis Crick, who discovered the structure of DNA, called McClintock one of the most important "three M's" of science; the other two are geneticists Gregor Mendel and Thomas Hunt Morgan....