A yellow so faint that the color seemed almost illusory--China cuff link

Celia's eyes questioned David, and he shook his head. Eddie didn't know what they were doing in the other lab. They walked past the tanks, row after row of them, all sealed, with only needles that moved now and then and the dials on the sides to indicate that there was anything inside. They returned to the corridor. David led her through another doorway, a short passage, then into the second laboratory, this one secured by a lock that he had a key for.
Walt looked up as they entered, nodded, and turned again to the desk where he was working. Vlasic didn't even look up. Sarah smiled and hurried past them and sat down before a computer console and began to type. Another woman in the room didn't seem to be aware that anyone had come in. Hilda. Celia's aunt. David glanced at Celia, but she was staring wide-eyed at the tanks, and in this room the tanks were glass-fronted. Each was filled with a pale liquid, a yellow so faint that the color seemed almost illusory. Within the tanks, floating in the liquid, were sacs, no larger than small fists. Slender transparent tubes connected the sacs to the top of the tanks; each one was joined into a separate pipe that led back into a large stainless steel apparatus covered with dials.
Celia walked slowly down the aisle between the tanks, stopped once midway, and didn't move again for a long time. David took her arm. She was trembling slightly.
"Are you all right?"
She nodded. "I . . . it's a shock, seeing them. I . . . maybe I didn't quite believe it." There was a film of perspiration on her face.
"Better take off the coat now," David said. "We have to keep it pretty warm in here. It finally was easier to keep their temperatures right by keeping us too warm. The price we pay," he said, smiling slightly.
"All the lights? The heat? The computer? You can generate that much electricity?"
He nodded. "That'll be our tour tomorrow. Like everything else around here, the generating system has bugs in it. We can store enough power for no longer than six hours, and we just don't let it go out for more than six hours. Period."
"Six hours is a lot. If you stop breathing for six minutes, you're dead." With her hands clasped behind her, she stepped closer to the shiny control system at the end of the room. "This isn't the computer. What is it?"