Light micrograph of Euglena viridis, a flagellate protozoan common in stagnant & slow moving water. The flagellates are considered the most primitive group of protozoans because they contain both plant-like & animal-like organisms. E. viridis falls halfway between the two kingdoms. It contains the green pigment chlorophyll and produces energy by photosynthesis, but also absorbs organic substances dissolved in the water. If deprived of sunlight, it loses its green pigment & survives, in an animal-like manner, solely on dissolved nutrients. Magnification: x450 at 35mm size.