The development of a “palmelloid” phase was studied in an adventive growth of a species of the blue‐green alga Anabaena sp. and in culture of the same strain. The primary change from its characteristic filamentous structure was the separation of the cells from one another. This was accompanied by the excessive production of capsular slime in which the separated cells were arranged at random. Associated with this were a gross change in cytology and a change in shape of cell from spheroidal to enlarged ellipsoidal. Fresh culturing of palmelloid cells resulted in the resumption of the typical filamentous growth, which in time reverted to the palmelloid phase.

The development of a “palmelloid” phase was studied in an adventive growth of a species of the blue‐green alga Anabaena sp. and in culture of the same strain. The primary change from its characteristic filamentous structure was the separation of the cells from one another. This was accompanied by the excessive production of capsular slime in which the separated cells were arranged at random. Associated with this were a gross change in cytology and a change in shape of cell from spheroidal to enlarged ellipsoidal. Fresh culturing of palmelloid cells resulted in the resumption of the typical filamentous growth, which in time reverted to the palmelloid phase.