The manuscripts of father William Mitchell and daughter Maria Mitchell are not easily separated, and are treated here together. The collection includes William Mitchell's autobiography, his memoir of Judge Walter Folger of Nantucket, astronomical and meteorological observations, lectures, family and other correspondence.

This collection contains correspondence and reports and documents Florence Seibert's work at Yale University, under Lafayette Benedict Mendel; at the University of Chicago, under H. Gideon Wells; and at the Henry Phipps Institute at the University of Pennsylvania, 1932-1959. There are cancer research folders concerning her later work at the Mound Park Hospital Foundation and the Bay Pines V. A. Center, in St. Petersburg, Florida. There are also substancial amounts on Goucher College (her alma mater); Lilly Research Laboratories; Merck, Sharpe & Dohme; and Parke, Davis & Company.

This collection includes correspondence, research data, reviews of grant proposals, organizations participated in, laboratories worked for, and student recommendations. The correspondence in the collection dates primarily to the 1960s-70s, when Mildred Cohn worked at the University of Pennsylvania and at the Institute for Cancer Research in Philadelphia, later renamed, Fox Chase Cancer Center. The letters are professional in content, discussing biochemistry, molecular biology, nuclear magnetic resonance (NMR) experiments. The letters also concern lectures and participation in conferences and symposia, and there are materials relating to recommendations for students and colleagues for positions and promotions. Dr. Cohn's interest and involvement in the issue of women in science is presented, of particular note, her work with the University of Pennsylvania's Gender Equity Committee. The notebooks, by Cohn, her colleagues and students, contain extensive experimental data.

The maize geneticist Barbara McClintock (1902-1992) is credited with the discovery of "jumping genes," that is chromosomal "crossing over" and translocation. She received the Nobel Prize in Physiology or Medicine in 1983. The collection is organized into six series: I. Correspondence, 1931-1991; II. Subject files, 1938-1989; III. Works by McClintock, 1944-1989; IV. Works by others, 1927-1991; V. Research notes, notebooks, and card files, 1930s-1990s ; VI. Photographs, 1928-1991.