"Meanwhile I keep in contact with your hand until the instant that you become submerged. Now your mind is in me, see?—ready for transfer into Philip, where it will act as my Agent. That's how simple it is! Come on up and we'll go through the motions."

Quest experienced a shiver as he mounted the bridge. Annoyed with himself, he shrugged the feeling off. There was no risk here. Moreover, it was a part of his daily work to take chances; he had done so a hundred times without hesitation. Now he moved all the more quickly, as if to belie the squeamishness that possessed him in spite of himself.

Swinging past Clason on the plank, he lowered himself without a pause to the bottom rung of the ladder, while the inventor, hanging head down, maintained contact with him.

"No need to stay here," he said in sudden irritation. "I understand perfectly what I am to do."

"I'm testing my own acrobatic ability," grunted Clason amiably. "Just a minute now."

He wriggled as if trying to adjust himself to a better balance, but in reality to mask the motion of his free hand with which he reached up and pressed a button in the side of the plank. Instantly the structure, pivoting downward on its wall-socket, plunged Quest to his waist in the osmotic solution.

"For God's sake get out of the way!" he shouted, trying to wrench his hand out of Clason's sinewy grip. "Let go, I tell you!"

But Clason clung like a leech, his teeth gritted under the strain. Again the plank lurched downward, and with a violent splash Quest vanished below the surface.

Quick as a cat, Clason scrambled up the ladder and back to the base of the plank, where he erased and interchanged the chalk-marked signs with which he had misled Quest. Then with a sinister twist of a smile he threw the switch to minus, and turned to watch as the plank slowly righted itself and the vacant ladder came clear of the liquid.

For some time he stood staring at the gleaming colored rings of his dissociation-vat like some witch over her cauldron, his lips working, his hands clasping and unclasping like the tentacles of some sub-sea monster. Then, as if the spell had suddenly broken, he turned on his heel and switched off the light. As he hastened down the passageway toward his office, the airlock sucked the door against its jamb with an ominous whistle.