two points tie in together." He looked about him sharply, and then went on. "The nitrates are easily leached from the soil. Without the bacteria that grow around certain roots to fix nitrogen and form new nitrates, the soil was soon depleted.

"As to the complete lack of organic material, I can hazard only a guess. Time, of course. But, back of that, probably the usual history of an overpopulation, and a depleted soil. At the end, perhaps they ate everything, leaves, stems and roots, and returned nothing to the earth."

"The nitrates are replaceable?" Renner asked.

Beeson nodded.

"The nitrates will have formed deposits," he said, "probably near ancient lakes or shallow seas. It shouldn't be too hard to find some."

Renner turned to Farrow.

"How about your department?" he asked.

"I take it we're thinking of farming," Farrow said. "I've got equipment that will break up the soil for you. And I can throw a dam across the stream for water."

"There are seeds in the ship," Renner said, his eyes lighting with enthusiasm. "We'll start this planet all over again!"

"There's still one thing," Beeson reminded him drily. "Humus! Leaves, roots, organic material! Something to loosen up the soil, aerate it. Nothing will grow in a brick."

Renner stood up. He took a few slow paces, and then stood looking out at the groups of boulders studding the ancient plain.

"I see," he said. "And there's only one place to get it. We'll have to use the lichens and the mosses."

"There'll be trouble with the natives if you do," Thorne said.

Renner looked at him. He frowned thoughtfully.

"You'll be taking their only food," the doctor pointed out.

"We can feed them from the synthetizer," Renner answered. "We know that they will eat it."

"Why bother?" Farrow asked sourly.

Renner turned on him.

"Will the synthetizer handle it?" he asked.

"I guess so," Farrow grumbled. "For a while, at least. But I don't see what good the natives are to us."

"If we take their food," Renner said, "we're going to feed them. At least until such time as the crops come in, and they are able to feed themselves!"

"Are you building this planet for us, or for them?" Farrow demanded.

Renner turned away.

They put out cannisters of food for the natives that night. In the morning it was gone. Each evening, someone left food for them near their favorite nest of rocks. The natives took it in the dark, unseen.

Gradually, Captain Renner himself took over the feeding. He seemed to derive a personal satisfaction from it. Gradually, too, the natives began coming out into the open to receive it. Before long, they were waiting for him every evening as he brought them food.

The gathering of the lichen began. They picked it by hand, working singly or in pairs, searching out the rocks and hidden places where it grew. From time to time they would catch glimpses of the natives watching them from a distance. They were careful not to get close.

On one of these occasions, Captain Renner and David were working together.

"Do they have a language?" Captain Renner asked.

"Yes, sir," David answered. "I have heard them talking among themselves."

"Do you suppose you can learn it?" Renner asked. "Do you think you could get near enough to them to listen in?"

"I could try," David offered.

"Then do so," Renner said. "That's an assignment."

Thereafter David went out alone. He found that getting close to the natives was not too difficult. He tried to keep out of their sight, while still getting near enough to them to hear their voices. They were undoubtedly aware of his presence, but, with the feeding, they had lost their fear of the men, and did not seem to care.

Bit by bit he learned their language, starting from a few key roots and sounds. It was a job for which he had been trained.

Time passed rapidly, and the work went on. Captain Renner let his beard grow. It came out white