Fantastic Voyage - By Isaac Asimov Page 0,59

damage we do will, in any case, be minimal."

A clump of fibers pulled loose as the Proteus nudged into it, slipped and slid along the window and vanished past the sides. It happened again and again with increasing frequency.

"It's all right, Owens," said Michaels, encouragingly, "the body can repair damage like this without trouble."

"I'm not worried about Benes," called out Owens. "I'm worried about the ship. If this stuff clogs the vents, the engine will overheat. And its adhering to us. Can't you tell the difference in the engine sound?"

Grant couldn't, and his attention turned to the outside again. The ship was- nosing through a forest of tendrils now. They glinted a kind of menacing maroon in the headlights.

"We'll get through it soon," said Michaels, but there was a definite note of anxiety in his voice.

The way did clear a bit and now Grant could indeed sense a difference in the sound of the engines, almost a thickening hoarseness, as though the clear echo of gases bubbling through exhaust vents were being muffled and choked off.

Owens shouted, "Dead ahead!"

There was a soggy collision of a bacterial rod with the ship. The substance of the bacterium bent about the curve of the window, sprang back into shape and bounced off, leaving a smear that washed off slowly.

There were others ahead.

"What's going on?" said Grant in wonder.

"I think," said Michaels, "I think we're witnessing antibody reaction to bacteria. White cells aren't involved. See! Watch the walls of the bacteria. -It's hard by the reflection of miniaturized light, but can you see it?"

"No, I'm afraid I can't."

Duval's voice sounded behind them. "I can't see anything, either."

Grant turned, "Is the wire adjusted, doctor?"

"Not yet," said Duval. "I can't work in this mess. It will have to wait. What's this about antibodies?"

Michaels said, "As long as you're not working, let's have the inner lights out. Owens!"

The lights went out and the only illumination came from without, a ghostly gray-maroon flicker that placed all their faces in angry shadow.

"What's going on outside?" asked Cora.

"That's what I'm trying to explain," said Michaels. "Watch the edges of the bacteria ahead."

Grant did his best, narrowing his eyes. The light was unsteady and flickering. "You mean those small objects that look like BB-shot."

"Exactly. They're antibody molecules. Proteins, you know, and large enough to see on our scale. There's one nearby. See it. See it."

One of the small antibodies had swirled past the window. At close quarters it did not seem to be a BB-shot at all. It seemed rather larger than a BB and to be a tiny tangle of spaghetti, vaguely spherical. Thin strands, visible only as fine glints of light, protruded here and there.

"What are they doing?" asked Grant.

"Each bacterium has a distinctive cell-wall made out of specific atomic groupings hooked up in a specific way. To us, the various walls look smooth and featureless; but if we were smaller still-on the molecular scale instead of the bacterial-we'd see that each wall had a mosaic pattern, and that this mosaic was different and distinctive in each bacterial species. The antibodies can fit neatly upon this mosaic and once they cover key portions of the wall, the bacterial cell is through; it would be like blocking a man's nose and mouth and choking him to death.

Cora said excitedly, "You can see them cluster. How - how horrible."

"Are you sorry for the bacteria, Cora?" said Michaels, smiling.

"No, but the antibodies seem so vicious, the way they pounce."

Michaels said, "Don't give them human emotions. They are only molecules, moving blindly. Inter-atomic forces- pull them against those portions of the wall which they fit and hold them there. It's analogous to the clank of a magnet against an iron bar. Would you say the magnet attacks the iron viciously?"

Knowing what to look for, Grant could now see what was happening. A bacterium, moving blindly through a cloud of hovering antibodies, seemed to attract them, to pull them in to itself. In moments, its wall had grown fuzzy with them. The antibodies lined up side by side, their spaghetti strand projections entangling.

Grant said, "Some of the antibodies seem indifferent. They don't touch the bacterium."

"The antibodies are specific," said Michaels. "Each one is designed to fit the mosaic of a particular kind of bacterium, or of a particular protein molecule. Right now, most of the antibodies, though not all, fit the bacteria surrounding us. The presence of these particular bacteria has stimulated the rapid formation of this particular variety of antibody. How this stimulation