Barbara McClintock (1902-1992) used this microscope in the 1940s and 1950s for research on transposing genetic elements or “jumping genes” in maize. In this process, segments of DNA jump from one location on a chromosome to another. When Dr. McClintock published her results, she met with skepticism from many fellow geneticists. However, in 1983 she was awarded the Nobel Prize for her work. It was eventually determined that these elements are found in virtually all living organisms.
This instrument, made by the Bausch & Lomb Optical Co., is fitted with a circular mechanical revolving stage designed specifically for photomicrography. Dr. McClintock gave the microscope, and its set of apochromatic lenses, to Dr. Joseph C. Gall of the Carnegie Institution in Washington, D.C. in the summer of 1977. She told him she no longer needed it and wanted it to be in safe hands. In 1993 the Carnegie Institution donated the instrument to the Smithsonian Institution.