Fis' sion, a method of reproduction used in all cells, by which a cell divides itself into two, usually through the center. See also Conjugation and Budding.
Fla gel' lum (pl. flagella), vibrating hairs larger than cilia and less numerous.
Food-balls, bits of food inside the cells of many one-celled animals, usually showing through the walls.
Food-vacuole, a small drop of water containing digestive material and a food-ball.
Fo ra' men, an opening or short passage.
Gall-bladder, a membranous sac for the storage of gall, or bile, at the lower edge of the liver (syn. "bile sac").
Gas ter op' o da, the class to which the snail belongs.
Ge' nus (pl. genera), a group of closely related species.
Germ-spot, the region in the bird's egg in which development first takes place.
Gill, an apparatus for breathing the air dissolved in water.