Manipulating substances with Physarum polycephalum

Abstract The plasmodium of Physarum polycephalum is a large single cell capable for optimal spanning of food sources and avoidance of harmful stimuli. The sophisticated foraging behavior of the plasmodium can be interpreted in terms of computation. When propagating on a substrate with distributed sources of food the plasmodium simulates a general-purpose storage modification machine, approximates varieties of proximity graphs and imitates calculation of shortest path and plane tessellation. The plasmodium's behaviour is determined by the space–time distribution of attracting and repelling sources, and immediately guided by the waves of excitation traveling inside the plasmodium. Due to cytoplasmic streaming a harmless colored substance can be naturally ingested by the plasmodium and distributed inside the protoplasmic network. We show that by controlling the plasmodium's propagation over an uncolored substrate we can ‘fill’ specified areas of the substrate with the color transported by the plasmodium. We experimentally demonstrate that the plasmodium of P. polycephalum excels in adaptive transportation, mixing and transformation of colored food particles. We uncover a range of operations implementable by the plasmodium over color set, and design methods to control mixing and transportation of colors.