don't mind this planet so much.

He walked ahead, Mark following almost reluctantly. The ground was rocky and the shrub-like vegetation sparse and stunted, ranging in color from greenish gray to brown. It seemed hardly capable of supporting a large animal population. If there were any animals here at all, they were probably too small to be impressive, and would be of little interest to exhibitors.

They walked in silence for a few moments, and then Sam asked, "Want to go on?"

"I want to finish my studying."

That was something new. "Okay," said Sam, and turned back.

They were approaching the ship when the sound of a pebble falling came to Sam's ears. Automatically, his hand reached for his gun, and he swung around to face what might be danger. As he did so, something snarled and fled. He could see no sign of motion, but he could hear the scattering of other pebbles along a gully as the creature retreated.

"Looks like we're not alone here, after all," he said. "Wonder what that was."

"It couldn't have been very big," said Mark. "Big animals don't run away."

"Not usually, unless they're smart, or they've met people before. I'll have to set traps."

"Do you think maybe if you caught him you could sell him to a circus, Pop?"

"I'll have to see what he's like, first," said Sam. He looked around. "If there's one animal, there are likely to be others. It's strange that I didn't detect any sign of them."

He put his arm absently over Mark's shoulder. He didn't notice the expression on the kid's face at this unexpected gesture.

When they were inside the ship again, Mark said, "Guess I'd better get back to my arithmetic."

"In a minute," said Sam. "I want to talk to you first." He dropped wearily into a seat, although he had done nothing that should have tired him out. His son looked at him expectantly. "Mark, do you like traveling around with me?"

"Sure, Pop, I like to be with you."

"Not seeing anybody else? No other kids, no people of any kind? Just being with me, learning your lessons from tapes, and having your test papers corrected automatically? You don't get tired of it?"

Mark hesitated despite himself. Then he said loyally, "I'd rather be with you than anybody else. When Mom—when Mom died—I didn't want to see anybody."

"I know how you felt. But that was four years ago. You can't grow up alone. Now what you need to do is meet people, learn how they talk and think and feel. You can't learn those things from tapes, and you can't learn them from me."

Mark said stubbornly, "I like to be with you."

"I'm not much of a person to be with. Don't think I don't know it. I'm mean and surly, and my temper's getting worse by the day. I can't associate with people any more. But you can. I was thinking maybe I'd leave you—"

"No!" cried Mark.

"Not in an orphanage or anything like that. But I have some friends whose kids are growing up—"

"No. I won't go. If you send me, I'll run away. I want to be with you."

"Okay," said Sam. "That's that."

But it wasn't, and he knew it. Even as he went about preparing his traps, he knew it.

As it turned out, the only animals he caught in his traps were small ones which tore themselves in two and then scampered off, each half running in a different direction. For the animal which had made those noises, no traps were necessary. Later on he heard a noise outside again, and he went out cautiously, gun in hand. The animal backed away, but he saw it, then he heard it bark. So did Mark, who had followed him.

Mark's eyes almost popped. It was four years since he had heard the sound, but he knew at once what it was. "Gosh! A dog! How do you s'pose he got here?"

"I don't know,"