Plasmodium of Physarum polycephalum as a synchronous contractile system.

The contractile activity of veins and the rhythmicity of the frontal progress were photometrically recorded from cine-film, at numerous points across the whole plasmodium. Graphic analysis of the obtained curves demonstrates the existence of common contraction rhythm over the entire network, coincident to the expansion rhythm of the advancing front. It is suggested that the plasmodium of Physarum polycephalum represents an imperfectly synchronized monorhythmic contractile system.