Fantastic Voyage - By Isaac Asimov Page 0,58

journey to the brain."

"Why didn't we enter the lymphatics to begin with, then?"

"They are small. An artery is a much better target for a hypodermic; and the arterial current was expected to carry us to target in minutes. It didn't work out and to make our way back into an artery from here would delay us badly. Then, once we reached the artery, we would receive a battering which the ship might no longer be able to take."

He spread out a new set of charts and called out, "Owens, are you following Chart 72-D?"

"Yes, Dr. Michaels."

"Make sure you follow the path I've traced. It will take us through a minimum number of nodes."

Grant said, "What's that up ahead?"

Michaels looked up and froze. "Slow the ship," he cried.

The Proteus decelerated vigorously. Through one portion of the wall of the now widening tube, a shapeless mass protruded, milky, granular and somehow threatening. But as they watched, it shrank and vanished.

"Move on," said Michaels. He said to Grant. "I was afraid that white cell might be coming, but it was going, fortunately. Some of the white cells are formed in the lymph nodes, which are an important barrier against disease. They form not only white cells but also antibodies."

"And what are antibodies?"

"Protein molecules that have the capacity to combine specifically with various outside substances invading the body; germs, toxins, foreign proteins."

"And us?"

"And us, I suppose, under proper circumstances."

Cora interposed. "Bacteria are trapped in the nodes, which serve as a battleground between them and the white cells. The nodes swell up and become painful. You know- Children get what are called swollen glands in the armpits or at the angle of the jaw."

"And they're really swollen lymph nodes."

"That's right."

Grant said, "It sounds like a good idea to stay away from the lymph nodes."

Michaels said, "We are small. Benes' antibody system is not sensitized to us, and there is only one series of nodes we need pass through, after which we have clear sailing. It's a chance, of course, but everything we do now is a chance. -Or," he demanded, challengingly, "are you going to set policy by ordering me out of the lymphatic system?"

Grant shook his head, "No. Not unless someone suggests a better alternative."

"There it is," said Michaels, nudging Grant gently, "See it?"

"The shadow up ahead?"

"Yes. This lymphatic is one of several that enters the node, which is a spongy mass of membranes and tortuous passages. The place is full of lymphocytes ... "

"What are those?"

"One of the types of white cells. They won't bother us, I hope. Any bacteria in the circulatory system reaches a lymph node eventually. It can't negotiate the narrow twisting channels."

"Can we?"

"We move deliberately, Grant, and with an end in view, whereas bacteria drift blindly. You do see the difference, I hope. Once trapped in the node, the bacterium is handled by antibodies or, if that fails, by white cells mobilized for battle."

The shadow was close now. The golden tinge of the lymph was darkening and turning cloudy. Up ahead there seemed a wall.

"Do you have the course, Owens?" Michaels called out.

"I have, but its going to be easy to make a wrong turning."

"Even if you do, remember that at this moment we are heading generally upward. Keep the gravitometer indicator on the line as steadily as you can, and in the end you can't go wrong."

The Proteus made a sharp turn and suddenly all was gray.

The headlights seemed to pick up nothing that was not a shadow of a deeper or lighter gray. There was an occasional small rod, shorter than the ship and much narrower; clumps of spherical objects, quite small, and with fuzzy boundaries.

"Bacteria," muttered Michaels. "I see them in too great detail to recognize the exact species. Isn't that strange? Too much detail."

The Proteus was moving more slowly now, following the many gentle sweeps and turns of the channel almost hesitantly.

Duval stepped to the door of the work-room. "What's going on? I can't work on this thing if the ship doesn't hold a steady course. The Brownian motion is bad enough."

"Sorry, doctor," said Michaels, coldly. "We're passing through a lymph node and this is the best we can do."

Duval, looking angry, turned away.

Grant peered forward, "It's getting messy up there, Dr. Michaels. What is that stuff that looks like seaweed or something?"

"Reticular fibers," said Michaels.

Owens said, "Dr. Michaels."

"Yes?"

"That fibrous stuff is getting thicker. I won't be able to maneuver through them without doing some damage to them."

Michaels looked thoughtful. "Don't worry about that. Any