Nuclear division in Euglena spirogyra takes place within the nuclear membrane, and no centriole appears during the process. The nucleus moves forward into contact with the base of the reservoir. The chromatin in the vegetative nucleus is in the form of paired strands of chromomeres. These shorten and thicken in the prophase and lose their granular appearance, forming the chromosome pairs of the metaphase. The chromosomes are never arranged in a true equatorial plate, but the members of each pair move apart more or less individually in the anaphase and each chromosome undergoes a longitudinal fission as it resolves again into the granular state. The nuclear membrane constricts in the mid line following the movement of the chromosomes to the poles of the nucleus. The endosome lies in the center of the chromosome mass throughout the process. It becomes homogeneous early in the prophase; then elongates at right angles to the long axis of the body and constricts in halves preceeding the complete constriction of the nuclear membrane. It resumes its vegetative appearance in the reorganization period. The kinetic elements of the flagellum are derived from the endosome and lie in the nucleus during the vegetative life as the intranuclear body. Prior to division this divides; then moves to the nuclear membrane and, as the nucleus comes into contact with the base of the reservoir, the halves give rise to the blepharoplasts. Two new axial filaments grow out, one from each new blepharoplast, and unite with the original axial filaments. The axial filaments then become widely separated, splitting the original flagellum as they move apart. The two flagella for the daughter organisms are thus formed and grow out to their normal length following division. The rhizoplast connecting the nucleus to the blepharoplasts persists late into the vegetative stage and possibly throughout the whole of this period.