Throughout the 1930s and 1940s, McClintock traveled extensively across the United States and Europe to conduct research and share information about maize genetics with other prominent scientists in the field. She maintained regular correspondence with a familiar group of colleagues and friends--many of whom were part of her Cornell cohort--and would respond at length to their many research questions and problems. It was no surprise, then, that in the 1950s McClintock was invited to give lectures on her theory of controlling elements, as well as on important general themes in maize genetics, at universities around the U.S.
In the winter of 1954, for example, McClintock was invited to lecture over the course of an entire semester at the California Institute of Technology. Viewers can see complete notes--both typed and handwritten--for her lectures at Cal Tech, as well as for lectures at Brandeis University (April 1958), Columbia University (April 1964), and Cornell University (November 1965).