Correlation of contractile activity and of streaming direction between branching veins ofPhysarum polycephalum plasmodium

Summary Pulsation curves recorded in a lateral vein and in the main vein behind and ahead of junction demonstrate the existence of a common contraction-relaxation rhythm. Correlation of contraction periods is very strong in the major vein on both sides of the junction and strong between the major vein and its lateral branch. Correlation of streaming periodicities is also very strong along the major vein but inexistent between the main vein and the lateral one. There is a weak but significant positive correlation between the contraction periods and the forward direction of streaming in all the veins. No difference found in veins mean diameter at the periods of the forward and the backward streaming. The results are discussed in terms of the model of motory coordination involving the synchrony of contraction and a partial desynchronization of streaming in the network of plasmodium.Study supported by the Research Project II. 1 of the Polish Academy of Science.