English: Heliozoa. 1. Actinosphaerium eichhornii, Ehr.; a, nuclei; b, deeper protoplasm with smaller vacuoles and numerous nuclei; c, contractile vacuoles; d, peripheral protoplasm with larger vacuoles. 2. A portion of the same specimen more highly magnified and seen in optical section. a, Nuclei; b, deeper protoplasm (so-called endosarc); d, peripheral protoplasm (so-called ectosarc); e, pseudopodia showing the granular protoplasm streaming over the stiff axial filament: f, food-particle in a good-vacuole. 3, 4. Nuclei of Actinosphaerium in the resting condition. 5-13. Successive stages in the division of a nucleus of Actinosphaerium, showing fibrillation, and in 7 and 8 formation of an equatorial plate of chromatin substance (after Hertwig). 14. Cyst-phase of Actinosphaerium eichhornii, showing the protoplasm divided into twelve chlamydospores, each of which has a siliceous coat; a, nucleus of the spore; g, gelatinous wall of the cyst; h, siliceous coat of the spore.