"Then nobody has any idea what they're eating," said Marcus. "But what was that new protein? That's what I want to know." "It was hardy. It came from the most adaptable creature on Earth," said the robot. "And there was another factor in favor of it. The flesh of all mammals is nearly the same. But there are differences. The ideal protein for a meat-eating animal is one which exactly matches the creature's own body, eliminating food that can't be fully utilized." Marcus closed his eyes and grasped the arm of the chair. "Do you feel ill?" inquired the managing robot. "Shall I call the doctor? No? Well, as I was saying, there was already a supply of animal tissue on hand. It was this that the robots used. It's funny that you're asking this. Not many people are so curious." "They didn't care," snarled Marcus. "As long as they were fed, they didn't ask what it was." "Why should they?" asked the robot. "The tissue was already well adapted to growth tanks. Scrupulously asceptic, in no way did it harm the original donors who were long since dead. And there was little difference in the use of it, anyway. No one would hesitate if he were injured and needed skin or part of a liver or a new eye. This was replacement from the inside, by a digestive process rather than a medical one." "The robots took tissue from the surgery replacement tanks," said Marcus. "Do you deny it?" "That's what I've been telling you," said the robot. "A very clever solution considering how little time they had. However only about half of the tanks had to be replaced." "Cannibals," said Marcus, nearly destroying the chair as he hurled it away from him. "What's a cannibal?" asked the robot. But Marcus wasn't there to answer. He went back to the restaurant, under control by the time he reached the table. He couldn't tell Wilbur because Wilbur had finished eating except for the vegetables which were mostly untouched. Marcus sat down and took the shields off the food, looking at it gloomily. "Pa, aren't you going to eat?" asked Wilbur. "As soon as I get my breath back," he said. It wasn't bad when he ate, but the mere thought of food was distasteful. He glanced sternly at his son. "Wilbur, hereafter you may not order meat. As long as we are on Earth, you will ask for eggs." "Just eggs?" said Wilbur incredulously. "Gee, they're real expensive here. Anyway, I don't like them without a rasher of--" "Eggs," said Marcus. Another thought occurred to him. "Sunny-side up. No cook can disguise that." * * * * * The sky was dark when they left the restaurant. After work, traffic had abated and the entertainment rush hadn't come on the streets, which were now curiously silent and deserted. Marcus caught sight of the tall spire of Information Center glistening against the evening sky. "Where are we going?" asked Wilbur. "To the hotel. We have a hard day's work tomorrow." "Can we walk? I mean, we can't see anything in the tubes."