Stephanopyxis is capable of interrupting its vegetative reproduction by the formation of resting spores. The resting spores are formed in pairs via two differentiating cell divisions. The first division is equal, the second, however, extremely unequal, since during growth in the longitudinal direction the cell contents are polarized. Resting spores germinate by beginning with normal vegetative cell divisions. The walls of the spores are not shed but passed along from division to division.