He rubbed his forehead wearily. “We’ve got to try to find some sort of poison or corrosive agent, something that’ll destroy them wholesale. We can’t just sit and wait for them to attack us. We need something we can spray. That’s the way we got the twisty slugs.”

The Commander gazed past him, rigid.

He turned to follow her gaze. “What is it?”

“I never noticed two briefcases in the corner over there. There was only one before—I think.” She shook her head in bewilderment. “How are we going to know? This business is getting me down.”

“You need a good stiff drink.”

She brightened. “That’s an idea. But—”

“But what?”

“I don’t want to touch anything. There’s no way to tell.” She fingered the blast gun at her waist. “I keep wanting to use it, on everything.”

“Panic reaction. Still, we are being picked off, one by one.”

Captain Unger got the emergency call over his headphones. He stopped work at once, gathered the specimens he had collected in his arms, and hurried back toward the bucket.

It was parked closer than he remembered. He stopped, puzzled. There it was, the bright little cone-shaped car with its treads firmly planted in the soft soil, its door open.

Unger hurried up to it, carrying his specimens carefully. He opened the storage hatch in the back and lowered his armload. Then he went around to the front and slid in behind the controls.

He turned the switch. But the motor did not come on. That was strange. While he was trying to figure it out, he noticed something that gave him a start.

A few hundred feet away, among the trees, was a second bucket, just like the one he was in. And that was where he remembered having parked his car. Of course, he was in the bucket. Somebody else had come looking for specimens, and this bucket belonged to them.

Unger started to get out again.

The door closed around him. The seat folded up over his head. The dashboard became plastic and oozed. He gasped—he was suffocating. He struggled to get out, flailing and twisting. There was a wetness all around him, a bubbling, flowing wetness, warm like flesh.

“Glub.” His head was covered. His body was covered. The bucket was turning to liquid. He tried to pull his hands free but they would not come.

And then the pain began. He was being dissolved. All at once he realized what the liquid was.

Acid. Digestive acid. He was in a stomach.

“Don’t look!” Gail Thomas cried.

“Why not?” Corporal Hendricks swam toward her, grinning. “Why can’t I look?’

“Because I’m going to get out.”

The sun shone down on the lake. It glittered and danced on the water. All around huge moss-covered trees rose up, great silent columns among the flowering vines and bushes.

Gail climbed up on the bank, shaking water from her, throwing her hair back out of her eyes. The woods were silent. There was no sound except the lapping of the waves. They were a long way from the unit camp.

“When can I look?” Hendricks demanded, swimming around in a circle, his eyes shut.

“Soon.” Gail made her way into the trees, until she came to the place where she had left her uniform. She could feel the warm sun glowing against her bare shoulders and arms. Sitting down in the grass, she picked up her tunic and leggings.

She brushed the leaves and bits of tree bark from her tunic and began to pull it over her head.

In the water, Corporal Hendricks waited patiently, continuing in his circle. Time passed. There was no sound. He opened his eyes. Gail was nowhere in sight.

“Gail?” he called.

It was very quiet.

“Gail!”

No answer.

Corporal Hendricks swam rapidly to the bank. He pulled himself out of the water. One leap carried him to his own uniform, neatly piled at the edge of the lake. He grabbed up his blaster.

“Gail!”

The woods were silent. There was no sound. He stood, looking around him, frowning. Gradually, a cold fear began to numb him, in spite of the warm sun.

“GAIL!”

And still there was only silence.

Commander Morrison was worried. “We’ve got to act,” she said. “We can’t wait. Ten lives lost already from thirty encounters. One-third is too high a percentage.”

Hall looked up from his work. “Anyhow, now we know what we’re up against. It’s a form of protoplasm, with infinite versatility.” He lifted the spray tank. “I think this will give us an idea of how many exist.”

“What’s that?”

“A compound of arsenic and hydrogen in gas form. Arsine.”

“What are you going to do with it?”

Hall locked his helmet into place. His voice came through the Commander’s earphones. “I’m going to release this throughout the lab. I think there are a lot of them in here, more than anywhere else.”

“Why here?”

“This is where all samples and specimens were originally brought, where the first one of them was encountered. I think they came in with the samples, or as the samples, and then infiltrated through the rest of the buildings.”

The Commander locked her own helmet into place. Her four guards did the same. “Arsine is fatal to human beings, isn’t it?”

Hall nodded. “We’ll have to be careful. We can use it in here for a limited test, but that’s about all.”

He adjusted the flow of his oxygen inside his helmet.

“What’s your test supposed to prove?” she wanted to know.

“If it shows anything at all, it should give us an idea of how extensively they’ve infiltrated. We’ll know better what we’re up against. This may be more serious than we realize.”

“How do you mean?” she asked, fixing her own oxygen flow.

“There are a hundred people in this unit on Planet Blue. As it stands now, the worst that can happen is that they’ll get all of us, one by one. But that’s nothing. Units of a hundred are lost every day of the week. It’s a risk whoever is first to land on a planet must take. In the final analysis, it’s relatively unimportant.”

“Compared to what?”

“If they are infinitely divisible, then we’re going to have to think twice about leaving here. It would be better to stay and get picked off one by one than to run the risk of carrying any of them back to the system.”

She looked at him. “Is that what you’re trying to find out—whether they’re infinitely divisible?”

“I’m trying to find out what we’re up against. Maybe there are only a few of them. Or maybe they’re everywhere.” He waved a hand around the laboratory. “Maybe half the things in this room are not what we think they are… It’s bad when they attack us. It would be worse if they didn’t.”

“Worse?” The Commander was puzzled.

“Their mimicry is perfect. Of inorganic objects, at least. I looked through one of them, Stella, when it was imitating my microscope. It enlarged, adjusted, reflected, just like a regular microscope. It’s a form of mimicry that surpasses anything we’ve ever imagined. It carries down below the surface, into the actual elements of the object imitated.”

“You mean one of them could slip back to Terra along with us? In the form of clothing or a piece of lab equipment?” She shuddered.

“We assume they’re some sort of protoplasm. Such malleability suggests a simple original form—and that suggests binary fission. If that’s so, then there may be no limits to their ability to reproduce. The dissolving properties make me think of the simple unicellular protozoa.”

“Do you think they’re intelligent?”

“I don’t know. I hope not.” Hall lifted the spray. “In any case, this should tell us their extent. And, to some degree, corroborate my notion that they’re basic enough to reproduce by simple division—the worse thing possible, from our standpoint.

“Here goes,” Hall said.

He held the spray tightly against him, depressed the trigger, aimed the nozzle slowly around the lab. The commander and the four guards stood silently behind him. Nothing moved. The sun shone in through the windows, reflecting from the culture dishes and equipment.