SHUTTLE-STREAMING: SYNCHRONIZATION WITH HEAT PRODUCTION IN SLIME MOLD.

Two small blobs and a channel excised from a slime mold plasmodium were allowed to fuse into a dumbbell-shaped mass in a thermally insulated Kamiya double chamber equipped with naked bead thermistors in contact with the blobs. Cyclic temperature differences of from 1 X 10(-4) to 5 X 10(-2) deg Celsius were recorded by a sensitive lock-in amplifier method with a basal noise level of less than 2 X 10(-2)deg Celsius and a time constant of 0.5 second. The temperature differences were caused by periodic bursts of heat production synchronized perfectly with the shuttle-streaming cycle and invariably localized at the source rather than the destination of the streaming cytoplasm. The results support the theory that the motive force for cytoplasmic streaming in the slime mold is pressure, probably generated by contraction of elements in the channel walls.