The Farlow Diatom Collection substantially records the work of the international community of diatomists and botanists during the nineteenth and early twentieth centuries, especially from 1830 to about 1940. The Collection consists of about 30,000 microscope slides and field samples, which have been segregated as to whether they are parts of published or unique (unpublished) collections. This web site presents an annotated catalog of these collections.

Published Collections (Exsiccatae) - These are sets of packets and sheets of dried material or microscope slides, which were issued as replicates when they were distributed to the scientific community and the public. The specimens in them were given set-specific serial numbers with the consequence that each sample bears the same number in replicate collections at different herbaria and institutions.

Unique Collections (Unpublished Exsiccatae) - These sets of slides, packets and vials of dried samples generally include personal and institutional collections and isolated materials acquired by gift, exchange or purchase, but they were not issued as serially numbered samples in replicates sets, that is, they were unpublished. Much of the material in these sets is unique; each collection itself is unique.