The cytogeneticist John Belling (1866-1933) developed the iron-acetocarmine staining technique, which facilitated detailed study of chromosomal structures. In his work with Arthur F. Blakeslee at Cold Spring Harbor on Datura (1920-1927) and at the University of California, Berkeley (1928-1933) on lilies, hyacinths, and other plants, Belling made accurate estimates of chromosomal numbers, helped to demonstrate the interchange of segments between non-homologous chromosomes, and proposed that the chromomeres (small condensations of stain that appeared along the length of chromosomes) represented individual, physical genes. Although he was a gifted technician and insightful cytologist, his career was hampered by mental instability and curtailed by frequent hospitalizations before his sudden death in 1933. The Belling Collection consists of four photograph albums, 38 glass slides and approximately 75 glass negatives and positive prints of chromosome preparations made by Belling, primarily during the years at Berkeley, along with an annotated bibliographic card file. The images in the albums are fully identified, but most of the glass slides are not.

As a young graduate student at the University of Berlin in 1912, Eugen Teuber (1889-1958) was hired to help establish the Anthropoiden Station auf Teneriffa (Tenerife Primate Station) for the Prussian Academy of Sciences, the first field station devoted to behavioral research on primates. As its first director, Teuber played a crucial role in setting up the facilities and acclimating the chimpanzees to their new environment, and he was a co-participant in the first trials of Wolfgang Köhler's famous experiments to evaluate the intelligence of apes. The papers of Eugen Teuber document the founding and earliest years of the Anthropoiden Station auf Teneriffa. A small (0.5 linear feet), tightly focused collection, it contains a series of official documents relating to the establishment of the Station, approximately 20 letters between Teuber and officials in Berlin, including Wilhelm Waldeyer and Max Rothmann, some research notes, and over 100 photographs of the chimpanzees and facilities. The collection includes Teuber's notes on the first trial of Wolfgang Köhler's famous "fruit basket" experiment in December 1913.

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.

A bacteriologist from MIT, Salvador E. Luria's work with Max Delbruck on bacteriophage demonstrated that bacterial resistance to certain phages arose through genetic mutations. His later work showed that phages also mutate genetically. He received the Nobel Prize in Physiology or Medicine in 1969 with Max Delbruck and Alfred D. Hershey. The collection is organized into seven series: I. Correspondence, 1938-1992 ; IIa. Subject Files, 1938-1990 ; IIb. Personal Material. 1923-1991 ; III. Works by Luria, 1938-1987 ; IV. Works by Others, 1944-1990 ; V. Research Notes and Notebooks, 1941-1979 ; VI. Course Material, 1931-1991 ; VII. Photographs and Negatives, 1957-1982. Arrangement: Alphabetical by folder title and then chronological within each folder.