Division of Physarum mitochondria during starvation.

Microplasmodia of Physarum polycephalum used in this study form spherules after 18 h of starvation. Stereological morphometry revealed that between the 2nd and the 5th hour of starvation the number of mitochondria in 1 mm3 of cytoplasm rises from about 12 to 24 millions and the mean volume of mitochondria drops from circa 4.6 to 3.

The influence of dissection and of the contact with glass on the contractile activity of plasmodial strands.

The non-invasive photometric techniques recording the contraction-relaxation cycles demonstrate the absence of any lag period in pulsation of isolated veins in situ. Contractions are temporarily inhibited at the site of contact of the vein surface with a glass rod. This indicates that the results obtained with the techniques, in which glass sensors were used to detect the contractile activity, are not conclusive and provide no reliable data about the motive force generation site in plasmodium.

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.