AbstractPectinatella gelatinosahas only one generation of statoblasts a year. The statoblasts are dormant when they are formed in summer. When they were kept in water under laboratory conditions, dormancy was gradually broken from late autumn to early spring of the following year. No effective means was found to induce germination in the dormant statoblasts. Some substance(s) which inhibits the germination of statoblasts, hence called blastostasin, was demonstrated in the water in which statoblasts had been stored for a long period. The optimum temperature for germination is about 25°C. Light is an essential factor but is needed for only the initial phase of germination. Prolonged periods of illumination with strong light are inhibitory. Visible light with wavelengths longer than green is effective for germination. Undried statoblasts remained viable for more than three years. Some germination was also obtained from statoblasts dried for 20 months. Undried statoblasts can resist prolonged periods of freezing but are very sensitive to high temperature.It is suggested that the effectiveness of critical experimental factors varies with the previous history of statoblasts. Various unfavorable, but not lethal, treatments resulted in temporary loss of germinability and brought the statoblasts into a resting state, for which the term “induced dormancy” is prop