GROWTH-PATTERNS OF THE SLIME-MOLD PHYSARUM ON A NONUNIFORM SUBSTRATE

The Myxomycete Physarum polycephalum has been grown on nonuniform subs trates, where the nutrients were confined in separated drops of agar m edium. Spatial and temporal aspects of the resulting growth structures were studied by time-lapse Video techniques and analyzed using image processing software. The growth process on a linear substrate of drops can be described in terms of a searching phase alternating with a fee ding phase. On a linear array of drops; the Physarum advanced uniforml y after an initial lag phase. On a two-dimensional drop substrate two different growth regimes could be distinguished: branched growth was o bserved on substrates with small drop diameters and compact growth, si milar to growth on uniform substrates, was observed on substrates with larger drop diameters. The drop size is a crucial parameter that medi ates characteristic plasmodial morphologies. A crossover from branched to compact growth was observed in some of the experiments. A spatial correlation function was used that could quantitatively distinguish be tween the different growth regimes.