Abstract
The transition from the tetrasporangial F. rufolanosa phase to the gametangial phase of Asparagopsis armata was studied in unialgal culture. Falkenbergia was induced to form tetrasporangia in quantity by a medium low in nitrate or phosphate under short day conditions, i.e., 6-18 and 8-16 light: dark cycles at 3500 Rlx fluorescent light and a temperature of 15.degree. C. At liberation the tetraspores germinated to give rise to a Falkenbergia-like thallus, the apical cells of which produced segments that resembled those of Asparagopsis after 2 wk.