Fantastic Voyage - By Isaac Asimov Page 0,44

I WERE THERE."

Carter said, "Well, you tell Grant that I would rather a hundred times he ... No, don't tell him anything. Forget it."

The end of the heartbeat had brought the surge forward to a manageable velocity, and the Proteus was moving along smoothly again, smoothly enough to make it possible to feel the soft, erratic Brownian motion.

Grant welcomed that sensation, for it could be felt only in the quiet moments and it was those quiet moments that he craved.

They were all out of their harnesses again, and Grant, at the window, found the view essentially the same as in the jugular vein. The same blue-green-violet corpuscles dominated the scene. The distant walls were more corrugated, perhaps, with the lines lying in the direction of motion.

They passed an opening.

"Not that one," said Michaels at the console, where he labored painfully over his charts. "Can you follow my markings up there, Owens?"

"Yes, doc."

"All right. Count the turnings as I mark them and then to the right here. Is that plain?"

Grant watched the subdivisions coming at briefer and briefer intervals, dividing off right and left, above and below, while the channel along which they cruised became narrower, the walls more plainly seen and closer at hand.

"I'd hate to get lost in this highway pattern," said Grant, thoughtfully.

"You can't get lost," said Duval. "All roads lead to the lungs in this part of the body."

Michaels' voice was growing monotonous. "Up and right now, Owens. Straight ahead and then, uh, fourth left."

Grant said, "No more arterio-venous fistulas, I hope, Michaels."

Michaels shrugged him off impatiently; too absorbed to say anything.

Duval said, "Not likely. To come across two by accident is asking too much of chance. Besides we're approaching the capillaries."

The velocity of the blood-stream had fallen off tremendously and so had that of the Proteus.

Owens said, "The blood-vessel is narrowing, Dr. Michaels."

"It's supposed to. The capillaries are the finest vessels of all; quite microscopic in size. Keep going, Owens."

In the light of the headbeam it could be seen that the walls, as they constricted inward, had lost their furrows and creases and were becoming smooth. Their yellowness faded into cream and then into colorlessness.

They were taking on an unmistakable mosaic pattern, broken into curving polygons, each with a slightly thickened area near the center.

Cora said, "How pretty. You can see the individual cells of the capillary wall. Look, Grant." Then, as though remembering, "How's your side?"

"It's all right. Fine, in fact. You put on a very efficient band-aid, Cora. -We're still friendly enough for the use of Cora as your name, I hope?"

"I suppose it would be rather ungrateful of me to object to that."

"And useless, too."

"How's your arm?"

Grant touched it gingerly, "Hurts like the devil."

"I'm sorry."

"Don't be sorry. Just-when the time comes-be very, very grateful."

Cora's lips tightened a bit and Grant added hurriedly, "Just my poor way of being light-hearted. How do you feel?"

"Quite myself. My side feels a little stiff, but not bad. And I'm not offended. -But listen, Grant."

"When you talk, Cora, I listen."

"Band-aids aren't the latest medical advance, you know, and they're not the universal panacea. Have you done anything about warding off infection?"

"I put on some iodine."

"Well, will you see a doctor when we get out?"

"Duval?"

"You know what I mean."

Grant said, "All right. I will."

He turned back to the sight of the cell-mosaic. The Proteus was creeping now, inching through the capillary. In the light of its headbeams, dim shapes could be seen through the cells.

Grant said, "The wall seems to be translucent."

"Not surprising," said Duval. "Those walls are less than one ten-thousandth of an inch thick. They're quite porous, too. Life depends on material getting through those walls and through the equally thin walls that line the alveoli."

"The which?"

For a moment, he looked at Duval in vain. The surgeon seemed more interested in what he was looking at than in Grant's question. Cora hastened to fill the gap.

She said, "Air enters the lungs through the trachea; you know-the windpipe. That divides, just as the blood-vessels do, into smaller and smaller tubes until they finally reach the microscopic little chambers deep in the lung, where the air that enters finds itself separated from the interior of the body only by a narrow membrane; a membrane as narrow as that of the capillaries. Those chambers are the alveoli. There are about six hundred million of them in the lungs."

"Complicated mechanism."

"A magnificent one. Oxygen leaks across the alveolar membrane and across the capillary membrane, too. It finds itself in the blood-stream and