Summary

The feeding apparatus of Peranema trichophorum, consisting of cytostome and rodorgan, is independent of the reservoir system; the latter is the same in structure and function as that of other Euglenineae. There are two flagella, one directed forward, the other backward and adherent to the ventral body surface. The anterior flagellum is longer and thicker than the adherent one. Both flagella are composed of a central core and an outer sheath. Electron micrographs suggest that the core consists of many longitudinal fibrils, and the sheath of many short fibrils radiating from the core, giving the whole flagellum the appearance of a test-tubebrush. Treatment with certain proteindispersing agents cause the unfixed anterior flagellum todissociate into three fibrils.

Peranema multiplies freely on a diet of living yeast-cells; dead yeast is not suitable. Euglena viridis, E. gracilis, and certain other unicellular algae can also serve as food. Egg-yolk, and especially milk, can be used to maintain bacteria-free pure cultures. Casein is suitable in combination with soil-extract or beef-extract, but never as good as milk. With the latter the individuals are larger and tnore numerous than with yeast as food, although the cultures decline earlier. Clear liquid media of many various kinds did not support growth: paniculate food seems to be essential.

Peranema is capable of ingesting a great variety of living organisms provided these are motionless. Small organisms are swallowed whole; larger ones are either engulfed or cut open by the rod-organ and their contents sucked out. The rod-organ can be protruded out of thecytostome and used in holding on to, and cutting, the periplast of the prey. Starch-grains, oil-droplets, and protein-particles are engulfed and digested. The main food reserves are paramylon-granules and oil-droplets.

H⁺ ions, decomposition products of proteins, and other substances diffusingout of living, and particularly dead, organisms attract gliding Peranema. Chemotaxis plays an important role in leading Peranema to its prey.

Both gliding and swimming have been observed in normal individuals, although the latter is less frequent. While there can be no doubt that swimming results from the action of the anterior flagellum, it does not seem to play an appreciable part in gliding. Nothing is known about the function of the adherent flagellum.