Anna nodded. “This is going to create a sensation when we get back to Earth. We’ll have to take a lot of specimens back with us.”

She was reaching down towards the open container. One of the snowballs had fully opened and was a delicate white mass of feathery cilia. She put out her forefinger as though she intended to touch it.

“Don’t do that!” I shouted.

Maybe she was not even considering any such thing, but my loud command made her stiffen. She looked up at me angrily.

“You saved us, Captain Roker, and I appreciate that. But don’t forget who is in charge of this expedition. And don’t try to order me around — ever.”

“Don’t be a fool,” I said. “I wasn’t ordering you around — I was speaking for your own good. Don’t you have any idea what might be dangerous?”

My own tone must have betrayed my impatience and anger. Anna stiffened, and her color went from white to red.

“McAndrew has pointed out that these lifeforms would have been quite harmless if there had not been so many of them,” she said. And then she reached forward into the container and deliberately touched the expanded snowball with her forefinger. She looked up at me. “Satisfied? They’re perfectly harmless.”

Then she screamed. The ball was clinging to her finger as she withdrew it, and the cilia had enveloped it as far as the second joint.

“It won’t come off!” She began shaking her hand desperately. “It hurts.”

I swung my helmet hard at her finger, and the edge caught the ball near its middle. It was jarred loose and flew across the chamber. Anna stood and looked ruefully at her hand. The finger was reddened and swollen.

“Damnation. It stings like hell.” She turned accusingly to McAndrew and held forward her injured hand. “You fool. You told me they’re harmless, and now look at my finger. This is your fault.”

We all stared at her hand. The swelling on her forefinger seemed to be getting bigger and redder.

McAndrew had been standing there with a startled and perplexed expression on his face. Before I could stop him he picked up the laser that I had laid on the floor, aimed it at Anna, and pressed the switch. There was a crackle from the wall behind Anna, and the smoke of burned tissue. Her arm had been neatly severed above the elbow, and the wound cauterized with a single sweep of the instrument.

Anna looked at the stump with bulging eyes, groaned, and started to fall sideways to the floor.

“Mac!” I grabbed for the laser. “What the hell are you doing?”

His face was pale. “Come on,” he said. “Let’s get her to the robodoc. This isn’t too serious — she’ll have to wait to regenerate it until we get home and find a biofeedback machine, but we can’t help that.”

“But why did you do it?”

“I made one bad mistake, back there outside the air lock,” We were hurrying back through the ship, supporting Anna between us.

“I don’t want to make another one,” he went on. “Lanhoff’s notes on the single-celled organisms inside Manna pointed out that they didn’t have a sexual method of reproduction, but they have something that resembles the plasmids down on Earth — they swap sections of DNA with each other, to get the mixing of offspring characteristics. I wondered about that when I read it, because it suggests a mechanism for speeding up an evolutionary process. But I skipped on past it, because I was so sure there would be no evolutionary pressures at work inside Manna.”

We were almost at the Control Section of Star Harvester. Unless Will had gone mad and flown off in the transfer pod, we were only twenty minutes away from the Hoatzin’s robodoc. Anna was coming out of her faint, and groaning a little.

“Mac, I still don’t see it. Why does the evolution method of the creatures inside Manna mean you had to burn off Anna’s arm?”

“If they do swap tissue regularly, their immune reaction systems have to recognize and tolerate the exchange. But we’re not made like that — Anna’s immune reaction system might mop up the materials that the snowball transferred to her bloodstream, but more likely the stuff would have killed her. I daren’t take the chance.”

We had come to the hatch that led to the transfer pod. Will Bayes stood there. For a fraction of a second he looked relieved, then he took in the whole scene. We were all pale and panting. I was dragging Anna along while she lay in a near-faint with only a stump of a right arm; and McAndrew, wild-eyed and lunatic, was bounding along behind us, still brandishing the laser.

Will backed away in horror, his hands held in front of him. “Come on, man, don’t just stand there,” said McAndrew. “Get out of the way. We’ve got to get Anna over to our ship and let the doc have a go at her. The sooner the better.”

Will took a hesitant step to one side. “She’s not dead, then?”

“Of course she’s not dead — she’ll be good as new once she’s been through a regeneration treatment. We’ll have to keep her sedated for the trip back, but she’ll be all right.”

I went to the controls of the pod, ready to take us back to the Hoatzin. It hadn’t occurred to me that Anna would be quieted down now for the return trip, but I wouldn’t be the one to complain.

“You mean we’re actually going home?” asked Will. His tone suggested that he had never expected to see Earth again.

“Just for a while.” McAndrew had settled Anna as comfortably as he could, and now he was looking disconsolately around him for the bucket of lifeform samples that we had left behind in the Control Section of Star Harvester.

“We’ll be back, Will, don’t you worry,” he said. “Anna was quite right: when Lanhoff found Manna he stumbled across a real treasure trove. We’ve hardly scratched the surface. As soon as we can get organized, there’ll be another party from the Food Department. And I’m sure we’ll all be here with it.”

My attention was mainly on the controls, so I’m not sure that I heard Will’s low mumble correctly. But I think he was saying something about a transfer to the Energy Department.

The message was concise and clear:

Dear Captain Roker,

The Institute is sending a party to explore a region approximately half a light-year from Sol, for the purpose of verifying dark matter conjectures in current cosmological theories. Our projected departure date is six days hence. Knowing of your experience with Hoatzin-class ships employing the balanced drive, we wonder if you might be available to serve as a crew member for Project Missing Matter. If you are interested in so serving, I invite you to contact me or Dr. Dorian Jarver, at the above address.

Sincerely,

Arthur Morton McAndrew,

Research Scientist,

Penrose Institute.

Clear, but also totally baffling. It was no surprise that McAndrew wanted to test obscure scientific theories. That was his stock-in-trade. People who knew physics as I would never know it told me that McAndrew was better than anyone else alive, a name to be mentioned in the same breath as Newton and Einstein.

It was also predictable that he might be heading far out of the Solar System. He had done that whenever he thought there was something interesting to look at, or just when he needed a little time and space for serious solitary thinking. “I have to have it, Jeanie,” he’d said to me, a score of times. “It’s very nice to work with colleagues, but in my line of business the real stuff is mostly worked out alone.”

Nor was it odd that I was learning about the trip so late — a couple of times he had hared off on wild sorties far outside the Solar System, and I had been forced to chase after him and drag him out of trouble.