Plasmalemma invaginations of Physarum dependent on the nutritional content of the plasmodial environment

Quantitative estimates of plasmalemma invaginations in plasmodial veins of Physarum polycephalum were made under different conditions of nutrition. Pronounced differences were observed dependent on the nutritional content of the substrate. There was a decided increase in the number of plasmalemma invaginations in plasmodial veins grown on substrates containing absorbable food substances compared to veins migrating on non-nutrient substrates. This observation supports the proposition that the nutritional content, rather than the physical properties, of the substrate is the decisive factor for the formation of plasmalemma invaginations. The invaginations are believed to be concerned with the uptake of non-particulate food substances.