The Austrian biologist Paul Kammerer was an outspoken proponent of the theory of inheritance of acquired characteristics (Lamarckism) during the time in which Mendelian theory was becoming deeply entrenched in biology. His major research efforts, straddling the First World War, centered on experiments performed on salamanders and on the midwife toad, and seemed to provide empirical support for a Lamarckian mechanism in evolution. He also developed a monistic "law of seriality," in which he attempted to explain coincidence as the product of a higher order natural law. A Socialist, Kammerer was widely regarded as a brilliant scientist, but for scientific, personal, and political reasons, he engendered as much antagonism as support, preventing him from ever obtaining a regular university appointment. His career ended tragically in allegations of fraud, followed by his suicide. The Kammerer Papers is comprised of photocopies of materials that document the brief, but controversial career of a non-Darwinian evolutionary biologist. The bulk of the collection consists of photocopies of articles by Kammerer, often from obscure newspapers or periodicals, along with a small number of letters to his friend Hugo Iltis, the geneticist and biographer of Mendel. Nearly all of these pertain to the Kammerer's experiments with amphibians to test Lamarckian inheritance or to his other biological theories. The collection also includes a small number of items dating from after Kammerer's death, but relating to his life and work, including two letters from his former supervisor Hans Przibram, a letter from Hugh Iltis (Hugo's son) to Arthur Koestler and the reply, and a brief biographical reminiscence of Kammerer written by Hugo Iltis.

A botanist and historian of science at the University of Pennsylvania, Conway Zirkle published on the history of evolutionary thought and genetics, with a particular interest in the discipline as practiced in the Soviet Union. The Zirkle Papers consist of approximately one linear foot of materials accrued by Zirkle during research for his book on Lysenko-era biology in the Soviet Union, The Death of Science in Russia (1949). Among the miscellaneous materials in the collection are four volumes (0.5 linear feet) of pressed specimens of ferns and algae.

The collection includes three accessions: (1) a portion of Lewontin's correspondence files (mainly A-L) and copies of papers acquired in 1979; (2) a 2003 accession with files on various subjects and correspondence with about 30 colleagues, and (3) a substantial 2018 accession of about 60 linear feet that includes correspondence, manuscripts, and subject files. The topics discussed in the letters are numerous, including much on contemporary scientific controversies such as race, Darwin, evolution, intelligence, and biological determinism.