Coburn continued, "You see, they obviously come from a heavy planet and move differently. They're stronger than we are. Much like the way we'd be on the moon with one-sixth Earth gravity. They probably are used to a thicker atmosphere. If so, their eyes wouldn't be right for here. They'd need eyeglasses." "Major Pangalos didn't--" "Contact eyeglasses," said Coburn sourly. "Little cups of plastic. They slip under the eyelids and touch the white part of the eye. Familiar enough. But that's not all." The American colonel looked troubled. "I know contact lenses," he admitted. "But--" "If the Invaders have a thick atmosphere at home," Coburn said, "they may have a cloudy sky. The pupils of their eyes may need to be larger. Perhaps they're a different shape. Or their eyes may be a completely alien color. Anyhow, they need contact lenses not only to correct their vision, but to make their eyes look like ours. They're painted on the inside to change the natural look and color. It's very deceptive. But you can tell." "That goes to Headquarters at once!" snapped the colonel. He went out briskly. Coburn followed him out of the room to look for Janice. And Janice happened to be looking for him at exactly the same moment. He was genuinely astonished to realize how relieved he was that she was all right. He said apologetically: "I was worried! When I felt myself passing out I felt pretty rotten at having failed to protect you." She looked at him with nearly the same sort of surprised satisfaction. "I'm all right," she said breathlessly. "I was worried about you." The roaring of motors outside the hospital interrupted them. More and more vehicles arrived, until a deep purring filled the air. A Greek doctor with a worried expression hurried somewhere. Soldiers appeared, hard-bitten, tough, professional Greek soldiers. Hallen came out of a hospital room. The Greek general appeared with one of the two colonels who'd been at the airport. The general nodded, and his eyes seemed cordial. He waved them ahead of him into a waiting elevator. The elevator descended. They went out of the hospital and there was an armored car waiting. An impressive escort of motorcycle troops waited with it. * * * * * The Greek general saw Coburn's cynical expression at sight of the guards. He explained blandly that since oxygen brought sleeping Bulgarians out of their slumber--and had been used on them--oxygen was handy for use by anybody who experienced a bright flash of light in his mind. The Bulgarian soldiers, incidentally, said that outside the village of Ardea they'd felt as if the sunlight had brightened amazingly, but they felt no effects for two hours afterward, when they fell asleep at Naousa. So, said the general almost unintelligibly, if anything untoward happened on the way to the airport, everybody would start breathing oxygen. A sensation of bright light would be untoward.