Thus he establishes a third primary division of the living world, distinct from both animals and plants, under the name of the Protista, to include the Myxomycetes, the Diatomaceae, and the Labyrinthulae, which are commonly regarded as plants, with the Noctilucae, the flagellata, the Rhizopoda, the Protoplasta, and the Monera, which are most generally included within the animal world.
"Critiques and Addresses"
Thomas Henry Huxley