Even as I watched, the number and density of the white objects was increasing. The snowfall became a blizzard. And floating far away from me, almost at the limit of vision, I saw two great white shapes. They were travesties of the human form, bloated and blurred outlines like giant snowmen. Every second they grew bigger, as more and more snowballs approached and adhered to their surfaces. They were swelling steadily, rounding to become perfect spheres.

I shivered in my suit. Alien. The figures looked totally alien, but I knew what I had found. At their centers, unable to see, move, or send messages, were McAndrew and Anna. As I watched I thought of the guardian white corpuscles in my own blood-stream. The feathery balls were like them, busy leukocytes crowding around to engulf and destroy the foreign organisms that dared to invade the body of Manna.

How could I rescue them? They were in no danger for the first few minutes, but the snowballs would muffle the escape of heat from the suits. Unless the clinging balls were cleared away, Anna and McAndrew would soon die a blind and stifling death.

My first instinct was to open the lock and plunge through to the interior. Another look at the feathery snowballs changed my mind about that. They were thicker than ever, drifting up from the deep interior of the planetoid. If I went out there they would have me covered in less than a minute. The laser that I had brought with me was useless. If I used it in water, it would waste its energy turning a small volume close to me to steam.

And I had no other weapon with me.

Return to the Star Harvester, and look for inspiration there? It might be too late for McAndrew and Anna.

I went across to the side of the lock. There was a dual set of controls for the drilling shaft there, installed so that drilling progress could be monitored and modified on the spot. If I started the drill, the fluid ahead would offer little resistance. The tunnel would extend further into the liquid, far enough to enclose the area where the two misshapen spheres were floating. So if I opened the lock first, then activated the drill…

The timing would be crucial. Once the lock was open, liquid would be drawn into the evacuated area around me. Then I would have to operate the drill unit so that the open lock moved to enclose the two swollen masses of snowballs, close the lock again, and pump the liquid out. But if I was too slow, the blizzard of snow would close in on me, too, and I would be as helpless as McAndrew and Anna.

Delay wouldn’t help. I pressed the lever that opened the lock, moved to the side of the chamber, and started the drill extender.

Liquid rushed in through the opening aperture. I struggled to move forward against its pressure, fighting my way back to the lock control.

There was a swirling tide of white all around me. Feathered balls hit my suit and stuck to it, coating the faceplate in an opaque layer. Within thirty seconds I could not see anything, and my arms and legs were sluggish in their movements as I clung to the lock lever.

I had not anticipated that I would become blind so quickly. Were McAndrew and Anna already swept into the chamber by the advancing drill and the opened lock? I had no way of knowing. I waited as long as I dared, then heaved at the lever. My arm moved slowly, hampered by the mass of snow-spheres clinging to it. I felt the control close, and sensed the muffled roar of the pump. I tried to thrash my arms, to shake off the layers that clogged their movement. It was useless. Soon I was unable to move at all. I was in darkness. If the snowballs could tolerate vacuum, McAndrew and Anna and I would go the same way as Lanhoff; we’d be trapped inside our suits, our communication units useless, until the heat built up to kill us.

It was a long, long wait (only ten minutes, according to the communications link on board the ship — it felt like days). Suddenly there was a lightening of the darkness in front of my faceplate. I could move my arms again. The feather balls were falling off me and being pumped out through the airlock.

I turned around, peering through the one clear spot on my faceplate. There were two spherical blobs with me in the chamber, and they were gradually taking on human shapes. After another five minutes I could see parts of their suits.

“Anna! Mac! Turn around.”

They clumsily rotated to face me. I saw them staring out of the faceplates, white-faced but undeniably alive.

“Come on. Let’s get out of here.”

“Wait.” McAndrew was taking a bag from the side of his suit, opening it, and scooping up samples of liquid and snowballs. I decided that he was terminally crazy.

“Don’t fool with that, Mac — let’s get out of here.”

What was the danger now? I didn’t know, and I wasn’t going to wait to find out. I reached out, grabbed his arm, and began to haul him back through to the other chamber. We were still sloshing in a chaos of fluid and floating feather balls.

Anna grabbed at my arm, so I was towing both of them. I could hear her teeth chattering.

“God,” she said. “I thought we were dead. I knew it, it was just like being dead, no sound, nothing to see, not able to move.”

“I know the feeling,” I grunted — they were a weighty pair. “How did you get caught? I mean, why didn’t you get back into the airlock as soon as the snowballs arrived?”

We were scooting back up the tunnel as fast as we could, McAndrew still clinging to his bucket of specimens.

“We didn’t see any danger.” Anna was gradually getting control of herself, and her grip on my arm had loosened. “When we first came through the lock there were maybe half a dozen of those fuzzballs in sight. McAndrew said we ought to get a specimen before we left, because they were a more complex life-form than any that Lanhoff had reported. And then they started to arrive in millions, from all directions. Our suits were covered before we could get away — we didn’t have a chance.”

“But what are they — and what were they doing?” I said.

We had reached the top of the tunnel and entered the cargo sphere. There was no sign of Will Bayes — it occurred to me that I hadn’t sent him a single signal of any kind since I left. He must be frantic. I hit the switch that would fill the chamber with air. For some reason I was keener to get out of that suit than I had ever been.

McAndrew placed his container on the floor and we all began to work our way free, starting with the helmets.

“What were they doing? Now that’s a good question,” he said. “While we were stuck in the middle of them down there, I had time to give it some thought.”

Well, that sounded right. When McAndrew stops thinking, he’ll be dead.

“Lanhoff and I made a big goof,” he went on, “and for him it was a fatal one. We both argued that the food supply here was so plentiful that there’d be no pressure to evolve. But we forgot a basic fact. An organism needs more than food to survive.”

“What else? You mean moisture?” I had my suit off, and air had never tasted so good.

“Moisture, sure. But as well as that it needs warmth. Here on Manna, the evolutionary pressure is to get near a heat source. If you’re out too far from the center, you become part of the frozen outer layer. Those snowballs normally live down near the middle, getting as close as they can to the radioactive fragments that provide the warmth.”

Anna was out of her suit. Now that we were safe, she was making a tremendous effort to gain her self-possession, Her shivering had stopped and she was even patting at her damp and tangled hair. She peered curiously down at the container of feathered snowballs. They were still moving slowly around in the yellow liquid.

“The radioactivity must speed up their rate of evolution, too,” she said. “And I was thinking they wanted to eat us.”

“I doubt that we’re very appetizing, compared with their free soup,” said McAndrew. “No, if there hadn’t been so many of them they’d have been harmless enough. But when we came along, they sensed the heat given off by our suits, and they tried to cuddle up to us. They didn’t want to eat us, all they were after was a place by the fireside.”