Isaac Asimov - Fantastic Voyage II - Destination Brain

"Arkady, you will enter at an angle to the right. My cerebrograph tells me that, too. Just push in, will you?"

"Go ahead, Arkady," said Boranova. "We have no choice but to rely on Yuri's cerebrograph."

The ship moved forward and, as the prow touched the vein wall, Morrison could feel the slight vibration of the laboring motors. And then the wall simply gave and pulled away in all directions and the ship was inside.

Dezhnev stopped the motors at once. The ship moved in at a rapidly slowing pace, rebounded off the far wall (maintaining contact so briefly as to cause no damage that Morrison could see), and straightened out with the long axis of the ship along the enormous tunnel of the vein. The ship's width was better than half the width of the blood vessel.

"Well," said Dezhnev, "are we pointed in the right direction? If we're not, there's nothing to be done. I can't back up. We fit the vein too tightly for Albert to get out and turn us around and we have an insufficient remaining supply of energy to miniaturize further and make such a turn possible."

"You're pointed in the right direction," said Konev sternly. "Just get moving and you'll find out soon enough. The vessel will get larger as we move."

"Let's hope it does. - And if it does, how far do we have to travel before we can move out of the body?"

"I can't say yet," said Konev. "I have to follow the vein on my cerebrograph, consult with the people in the Grotto, and arrange for the insertion of a hypodermic needle into the vein as close as possible to the position in which we'll be when we emerge from within the cranium."

Dezhnev said, "May I explain that we cannot move on forever. What with miniaturizing and deminiaturizing, with steering at very low efficiency, with wrong capillaries, and with chasing after Albert when he was lost, we have used up much more energy than we had counted on using. We had much more energy than we thought we'd need, but, even so, we've almost used it all."

Boranova said, "Do you mean we're out of energy?"

"Just about. Haven't I been telling you this for quite a while?" said Dezhnev. "Haven't I been warning you we were running low?"

"But how low are we? Are you saying we don't have enough to carry us out of the cranium?"

"Ordinarily, we would have plenty for that, even now. If we were in a living vein, we could count on a blood current sweeping us along. But there is no current. Shapirov is dead and his heart isn't beating. That means I'll have to force my way through the bloodstream with my motors going and the cooler the stream gets, the more viscous it will become, the harder the motors will have to work, and the more rapidly the energy supply will run out."

Konev said, "We have only a few centimeters to go."

Dezhnev said furiously, "Only a few? Less than the width of my palm? Really? At our present size, we've got kilometers to go."

Morrison said, "Should we deminiaturize further, then?"

"We can't." Dezhnev was now speaking very loudly. "We don't have the energy for it. Uncontrolled deminiaturization takes no energy; it releases energy. But controlled deminiaturization - Look, Albert, if you jump out of a high window, you will reach the ground without effort. But if you want to survive the ordeal and if you want to be lowered slowly while you hang on to a rope, that takes a great deal of effort. Understand?"

Morrison muttered, "I understand."

Kaliinin's hand stole to his and squeezed it gently. She said in a low voice, "Don't mind Dezhnev. He grumbles and howls, but he'll get us there."

Boranova said, "Arkady, if vehemence doesn't guarantee truth, as you told us just now, neither does it guarantee a cool head and a solution. Rather, the reverse. So why don't you just push your way along the vein and perhaps the energy will last until we reach the hypodermic."

Dezhnev scowled and said, "It's what I will do, but if you want me to keep a cool head, you must let me get rid of some heat."

The ship began to move and Morrison thought to himself: Every meter we go is a meter closer to the hypodermic needle.

It didn't make much sense as a comforting thought, since to fail to reach the needle by a small distance might be as fatal as to fail by a large distance. Yet it worked to slow the beat of his heart and it gave him a sense of accomplishment as he watched the wall slide rapidly backward.

The red corpuscles and platelets seemed far more numerous now than they had been in the arteries and capillaries on the way in. Then there had been a blood flow and there had been only the relatively few objects in their immediate neighborhood that had moved along the flow with them. Now the various formed bodies were largely motionless and the ship moved past what seemed countless numbers, squeezing them right and left and leaving them behind, bobbing, in their wake.

They even passed an occasional white cell, large and globular and quiescent. Now, though, they were totally unresponsive to the presence of a foreign object speeding by. In one case, the ship simply whipped through a white cell and left it sprawling behind.

Konev said, "We are going in the right direction. The vein is now distinctly wider than it was."

And so it was. Morrison had noticed that without managing to grasp the significance. He had been too intent on simply moving.

He felt a small surge of hope. To have been going in the wrong direction would have been total disaster. The vein would have narrowed and burst, leaving them adrift in gray matter with, perhaps, insufficient fuel to find and reach another vein.

Konev was taking down something that Dezhnev was repeating to him. He nodded and said, "Have them confirm those figures, Arkady. - Good!"

He spent some time with his cerebrograph and then said, "Listen, they know the vein we're in and they will be inserting a hypodermic needle at a specific spot that I have marked off on the cerebrograph. We will reach it in half an hour or a little less. - Can you keep going for half an hour, Arkady?"

"More likely a little less. If the heart was beating -"

"Yes, I know, but it isn't," said Konev. Then he said, "Natalya, may I have whatever records you have concerning what we have sensed of Shapirov's thought processes? I am going to send the raw data - completeout to the Grotto."

Boranova said, "You mean in case we don't make it out."

"That's exactly what I mean. This material is what we went in for and there's no reason to have it perish with us if we can't get out."

"That's a proper attitude, Yuri," said Boranova.

"Provided," said Konev, his voice suddenly taking on a tinge of anger, "the data has any value at all." Briefly, he glared at Morrison.

Konev then bent toward Dezhnev and together the two began electronically transmitting the information they had collected, computer to computer, from tiny to large, from inside a vein to the outside world.

Kaliinin was still holding Morrison's hand, perhaps as much for comfort to herself as to him, Morrison thought.

He said in a low voice, "What happens, Sophia, if we run out of energy before we reach the needle?"

She lifted her eyebrows briefly and said, "We'll just have to remain passively in place. The people in the Grotto will try to reach us wherever we are."

"We won't deminiaturize explosively as soon as the energy is gone, will we?"

"Oh no. Miniaturization is a metastable state. You remember we explained that. We'll stay as we are indefinitely. Eventually - sometime - this chance pseudo-Brownian motion of expanding and contracting will set up spontaneous deminiaturization, but that might not be for - Who knows?"

"Years?"

"Possibly."

"That won't do us any good, of course," said Morrison. "We'll die of asphyxiation. Without energy, we won't be able to recycle our air supply."