History and classification
The first illustration of an amoeboid, from Roesel von Rosenhof's Insecten-Belustigung
The earliest record of an organism resembling Amoeba was produced in 1755 by August Johann Rösel von Rosenhof, who named his discovery "der kleine Proteus" ("the little Proteus"), after Proteus, the shape-shifting sea-god of Greek Mythology. While Rösel's illustrations show a creature similar in appearance to the one now known as Amoeba proteus, his "little Proteus'' cannot be identified confidently with any modern species.
The term "Proteus animalcule" remained in use throughout the 18th and 19th centuries, as an informal name for any large, free-living amoeboid.
In 1758, apparently without seeing Rösel's "Proteus" for himself, Carl Linnaeus included the organism in his own system of classification, under the name Volvox chaos. However, because the name Volvox had already been applied to a genus of flagellate algae, he later changed the name to Chaos chaos. In 1786, the Danish Naturalist Otto Müller described and illustrated a species he called Proteus diffluens, which was probably the organism known today as Amoeba proteus.
The genus Amiba, from the Greek amoibè (ἀμοιβή), meaning "change", was erected in 1822 by Bory de Saint-Vincent. In, 1830. the German naturalist C. G. Ehrenberg adopted this genus in his own classification of microscopic creatures, but changed the spelling to "Amoeba."