The Charles Drechsler Papers consist of the figures or illustrations for two articles that were published in the Journal of Botany in 1954 and 1956, titled "Two Species of Conidiobolus with Minutely Ridged Zygospores" and "Two New Species of Conidiobolus." There are also notes and pencil drawings for an unpublished article on Helminthosporium spp., a few letters, and specimens of cereal crops with plant diseases.

The Charles Thom Papers cover materials from Thom's college years to biographical memoirs published after his death. The collection includes correspondence, notes, notebooks, essays, lectures, speeches, diaries, journals, and lantern slides from professional trips. There are also published items, including monographs, journal articles, and newspaper clippings. The majority of the collection focuses on soil microbiology, mycology, food spoilage, food poisoning, and penicillin.