Over the course of twenty years (from 1845 to 1865), A. F. Middendorf was a full member of the St. Petersburg Academy of Sciences. During these years he processed materi als from his Siberian expedition, the results of which were published in a fourvoume work: “Reise in den aussersten Norden und Osten Sibiriens wahrend derJahren 1843 und 1844” (the last volume was also published in Russian). Middendorf actively participated in the life of the Academy of Sciences. The mate rials that he gathered in Siberia enriched the collections of the Academy’s muse ums, particularly those of the Zoological Museum. Middendorf also served as the elected permanent secretary of the Academy from 1855 to 1857.