Mucilage secretion and the movements of blue-green algae

Summary Recent discoveries of ultrastructures which might be involved in the gliding movements of blue-green algae have been reviewed, and in the light of these discoveries the role of mucilage secretion in movement has been reconsidered. The formation and behaviour of mucilage rings in filaments ofAnabaena cylindrica is described. The behaviour of the mucilage rings indicates that each cell has an autonomous gliding mechanism which is capable of immediate reversal, and that the gliding mechanism is probably located over the whole surface, rather than at the ends, of the cells. It follows that if mucilage secretion is the cause of movement it must take place over the whole surface of the cell: but if the ends of the cell are the sites of mucilage secretion, as seems likely, then gliding movement must be performed by some other process.A rather remarkable clumping phenomenon is described which takes place in dense suspensions ofAnabaena. It results from the gliding movements of randomly orientated filaments made mutually adhesive by the mucilage which surrounds them.