Cell division in morphological mutants ofAgmenellum quadruplicatum,strain BG-1

Summary Two types of filamentous mutants were derived from the unicellular blue-green alga,Agmenellum, by brief exposure to nitrosoguanidine. The parent exhibits constrictive division analogous to that of the enteric bacteria. The septate mutant exhibits septal division which is almost identical to that observed in all filamentous blue-green algae thus far described. In this mutant, the two outer wall layers fail to invaginate, leaving the daughter cells connected. The coenocytic filamentous mutant divides sporadically by both of these methods. The nuclear region of this mutant appears continuous throughout the length of the filament. It is suggested that the non-septate mutant is impaired in the coordination of cytological events leading to cell division.