Rapid degeneration of the protoplasm in artificially induced small cells ofMicrasterias crux melitensis

Summary Growing cells ofMicrasterias crux melitensis grew into asymmetric cells with small half cells in 0.2 M mannitol. Cells with small half cells could multiply in the normal culture medium. When mother half cells were less than half the size of the normal mother half cells small daughter half cells were formed. When the mother half cells were very small and had no chloroplasts, the protoplasts rapidly degenerated. Many autophagic vacuoles and lysosomes were found in the protoplasm of the degenerating cells. The rapid degeneration was assumed to be due to the activity of these autophagic lysosomes, whose induction is probably triggered by some factor produced by the shortage of protein precursors and energy sources.