position to the clot lead through the heart. The turbulence of the heart-passage would smash them to kindling in an instant and we can't take that chance."
"We...
"We can't, Carter. Not because of the lives of the men, though that's reason enough. If the ship is smashed, we'll never get all of it out and eventually its fragments will deminiaturize and kill Benes. If we get the men out now we can try operating on Benes from outside."
"That's hopeless."
"Not as hopeless as our present situation."
For a moment, Carter considered. He said, quietly, "Colonel Reid, tell me-without killing Benes, how long can we stop his heart?"
Reid stared. "Not for long."
"I know that. I'm asking you for a specific figure."
"Well, in his comatose state, and under hypothermic chilling, but allowing for the shaky condition of his brain, I would say no more than sixty seconds. On the outside."
Carter said, "The Proteus can plow through the heart in less than sixty seconds, can't it?"
"I don't know."
"They'll have to try, then. When we've eliminated the impossible, whatever remains, however risky, however slim a hope, is what we're going to try. -What are the problems involved in stopping the heart?"
"None. It can be done with a bare bodkin, to quote Hamlet. The trick will be to start it again."
"That, my dear colonel, is going to be your problem and your responsibility." He looked at the Time Recorder, which read 50. "We're wasting time. Let's get on with it. Get your heart-men into action and I'll have the men on the Proteus instructed."
The lights were on within the Proteus. Michaels, Duval and Cora, looking disheveled, clustered about Grant.
Grant said, "And that's it. They're stopping Benes' heart by electric shock at the moment of our approach and they'll start it again when we emerge."
"Start it again!" exploded Michaels. "Are they mad? Benes can't take that in his condition."
"I suspect," said Grant, "they consider it the only chance the mission has of succeeding."
"If that's the only chance, then we've failed."
Duval said, "I've had experience with open-heart surgery, Michaels. It may be possible. The heart is tougher than we think. -Owens, how long will it take us to pass through the heart?"
Owens looked down from the bubble. "I've been figuring out just that, Duval. If we have no delays, we can do it ill from fifty-five to fifty-seven seconds."
Duval shrugged. "We'd have three seconds to spare."
Grant said, "Then we'd better get on with it."
Owens said, "We're drifting with the current toward the heart right now. I'll shift the engines into high. I need to test them, anyway. They took a bad beating."
A muted throb rose somewhat in pitch and the sensation of forward motion overlay the dull, erratic trembling of Brownian motion.
"Lights out," said Owens, "and we'd better relax while I baby this thing along."
And with lights out, all drifted to the window again-even Michaels.
The world about them had changed completely. It was still blood. It still contained all the bits and pieces, all the fragments and molecular aggregates, the platelets and red blood corpuscles, but the difference-the difference. . .
This was the superior vena cava now, the chief vein coming from the head and neck, its oxygen supply consumed and gone. The red blood corpuscles were drained of oxygen and now contained hemoglobin itself, not oxyhemoglobin, that bright red combination of hemoglobin and oxygen.
Hemoglobin itself was a bluish-purple, and in the erratic reflection of the miniaturized light-waves from the ship, each corpuscle glittered in flashes of blue and green with a frequently interspersed purple. All else took on the tinge of these unoxygenated corpuscles.
The platelets slid by in shadow and twice the ship passed -at a most grateful distance-the ponderous heavings of a white blood-cell, colored now in greenish-tinged cream.
Grant looked at Cora's profile once more, lifted, as it was, with almost worshipful reverence, and itself looking infinitely mysterious in shadowy blue. She was the ice-queen of some polar region lit by a blue-green aurora, Grant thought quixotically, and suddenly found himself empty and yearning.
Duval murmured, "Glorious!" -But it was not at Cora that he was looking.
Michaels said, "Are you ready, Owens? I'm going to guide you through the heart."
He moved to his charts and put on a small overhead light that instantly dimmed the murky blue that had just filled the Proteus with mystery.
"Owens," he called. "Heart-chart A-2. Approach. Right atrium. You have it?"
"Yes, I have."
Grant said, "Are we at the heart already?"
"Listen for yourself," said Michaels, testily. Don't look. Listen!"
An unbreathing silence fell upon those within the