Electrical stimulation of luminescence in Ctenophores.

Abstract

A dark adapted specimen of Mnemiopsis, when subjected to the action of the galvanic current, reacts by a display of luminescence at the anode. In lively specimens the glow may extend to the middle of the animal, and last for as long as five seconds. The instant the current is broken the glow at the anode ceases and a momentary flash occurs on the cathodal side of the animal. These effects are observable whether the current be passed through the animal lengthwise or transversely. If a transverse incision be made in a specimen of Mnemiopsis, then, when the current is passed longitudinally through the animal, in the region of the cut surfaces luminous secondary anodes or cathodes appear whenever the animal is subjected to the make or break of the current. The reaction of Mnemiopsis to the galvanic current therefore constitutes a complete case of “reversed Pflüger's law”. The same phenomena may be demonstrated with specimens of Beroe, except that the effect of the break shock is not apparent in a luminescent flash at the cathode. In a solution of pure NaCl no galvanic stimulation of luminescence is possible, but in a solution containing 1 mol CaCl₂ to 500 NaCl galvanic stimulation occurs, although the luminescent flashes are of short duration. The current used was from 3 dry cells and from 2 to 10 milliamperes strength.

The fact that secondary regions of stimulation can be created by means of incision proves that the current produces excitation only at the protoplasm-sea-water surface, and that a movement of ions within the cells and their subsequent blocking at the cell boundaries is not in this case the cause of stimulation. This conclusion is further supported by experiments with the spark discharge from an influence machine.