Infusoria

[ in-fyoo-sawr-ee-uh, -sohr- ]

/ ˌɪn fyʊˈsɔr i ə, -ˈsoʊr- /

protozoans of the phylum Ciliophora (or class Ciliata).

(formerly) any of various microscopic organisms found in infusions of decaying organic matter.

Origin of Infusoria

1780–90; < New Latin, neuter plural of infūsōrius. See infuse, -ory¹

These are called Protozoa, and comprise the Infusoria and other microscopic organisms.
The Sea-beach at Ebb-tide|Augusta Foote Arnold
They are the cryptogamia of another world,—the infusoria of the skies.
Great Mysteries and Little Plagues|John Neal
Humboldt's assertion is fully verified in the case of the Infusoria under consideration, which is often found with its parasites.
The Ocean World:|Louis Figuier
Thus we often find the bodies of certain crustaceans covered with a forest of vorticell and other infusoria.
Animal Parasites and Messmates|P. J. Van Beneden

Most of these infusoria are lacustrine; but others are marine, particularly the tripolis of the Isle of France.
A Dictionary of Arts, Manufactures and Mines|Andrew Ure