[4] During his short interlude in Kassel, Pfeiffer was engaged in many artistic pursuits, particularly musical ones, and his lyric baritone was remarked on often by his brother Carl's friend (and later, his brother-in-law) Louis Spohr.

[8] Upon his return home, Pfeiffer undertook his first publication, a personal recollection of his experience entitled Erfahrungen über die Cholera, gesammelt in dem Hospital zu Warschau im Sommer 1831.

[8] In 1839, Pfeiffer was sent to Cuba with Johannes Gundlach and Eduard Otto in order to study the flora, fauna, and natural history of the West Indies, and it was this experience that piqued his interest in mollusks, conchology, and malacology.

[11] The group explored other islands in the Caribbean, but the experience had to come to and end, as the extended absence from home, which coincided with the deaths of his two remaining children, caused a rift between Pfeiffer and his wife that led to their divorce almost immediately upon his return to Europe in 1841.

[12] He proved to be a prolific publisher, and expanded his interest from conchology to the botany that had been his first love, writing several treatises on the nature flora of Hesse and its surrounding regions, coedited with the esteemed botanist Johann Cassebeer.

[13] In 1874, the increasingly frail Louis Pfeiffer undertook a two-month journey to Catalonia, where his eldest son Hermann was in business as a merchant, and the trip appears to have been an uneventful one, despite conceding directly with the coup d'état that toppled the First Spanish Republic.