Many of the Flagellata are parasitic (some haematozoic); the majority live in the midst of putrefying organic matter in sea and fresh waters, but are not known to be active as agents of putrefaction. Dallinger and Drysdale have shown that the spores of Bodo and others will survive an exposure to a higher temperature than do any known Schizomycetes (Bacteria), viz. 250° to 300° Fahr., for ten minutes, although the adults are killed at 180°.
The Flagellata are for the most part very minute; the Protomastigopoda rarely exceeding 20 μ in length. The Euglenaceae contain the largest species, up to 130 μ in length, exclusive of the flagellum.
Our classification is modified from those of Senn (in Engler and Prantl, Pflanzenfamilien) and Hartog (in Cambridge Natural History).
I. RHIZOFLAGELLATA (PANTOSTOMATA)
Food taken in by pseudopodia at any part of the body.
Order 1.—HOLOMASTIGACEAE. Body homaxial with uniform flagella. Multicilia (Cienkowski); Grassia (Fisch, in frog’s blood and gastric mucus).
Order 2.—RHIZOMASTIGACEAE. Flagellum 1, 2 or few, diverging from anterior end. Mastigamoeba (F.E. Schulze).
II. EUFLAGELLATA
Food taken in at one or more definite mouth-spots, or by a true mouth, or by absorption; or nutrition holophytic.
Order 1.—PROTOMASTIGACEAE. Contractile vacuole simple, one or more, or absent; either holozoic, ingesting food by a mouth-spot (or 2 or more), saprophytic, or parasitic.