Transmission electron micrograph (TEM) of the Lepocinclis sp. algae, showing the photoreceptor on locomotory flagellum; note crystalline structure. The surrounding flagellar membrane is close to the reservoir membrane, beneath which lie the eyespot droplets. The photoreceptive system guides the cell toward dim light optimal for photosynthesis. Magnification: 100,000X at 7 x 8" print size.