The Question With No Head

The sign was already printed when Maya saw the problem.

It stood on a little silver easel beside the shallow dishes, bright blue letters on white plastic.

CUT ONE PLANARIAN INTO TWO HUNDRED SEVENTY-NINE PIECES, GET TWO HUNDRED SEVENTY-NINE WORMS, EACH REMEMBERING THE MAZE.

Maya stopped so fast that Soren bumped her shoulder with his backpack.

"Too shiny," Maya said.

Soren looked at the sign, then at the dishes. Each dish held a sliver of brown-gray life no longer than an eyelash. Some had triangle heads. Some were still just commas with opinions.

"Too many two hundred seventy-nines," Soren said.

The curator swept past carrying a stack of visitor badges in her teeth and a tray of plastic pipettes in both hands. She had silver hair, orange shoes, and the speed of a person late to three places at once.

"Excellent, you found the planarians," she said around the badges. "Do not sneeze on them. Do not name them. If donors arrive, point to the sign. It is punchy. People remember punchy."

She vanished through the swinging door.

Maya leaned closer to the sign. "It says the wrong thing twice."

Soren had already taken out his paper notebook. He did not look embarrassed, even though the lab had screens built into the benches and glass walls that could display molecules in midair. His notebook was soft at the corners from being carried everywhere.

"First wrong thing," he said.

"The old experiment. It was a piece as small as one two-hundred-seventy-ninth of a worm. Not one worm chopped into exactly that many pieces."

"That would be worm confetti," Soren said.

"Second wrong thing. Remembering the maze. Too neat."

Soren flipped to a page where he had copied words from the lab packet. Planarians. Flatworms. Fresh water. Regenerate using neoblasts, adult stem cells. Avoid bright light. Some experiments report learned behavior returning after the head regrows.

He tapped the last line with his pencil.

"It does not say full memories," he said. "It says behavior. It says reports."

Maya smiled a very small smile. "So the sign is louder than the worms."

On the far bench sat the maze for the afternoon demonstration. It was not a maze like a garden maze. It was a clear plastic channel shaped like a Y, hardly bigger than Maya's thumb. At one end waited a dab of liver paste. Above it hung a white lamp.

Planarians hated light. They slid away from it if they could. That was part of why the demonstration was interesting. The lab had trained one flatworm, before it was divided, to cross a bright, rough-bottomed dish to feed. After pieces regrew heads and tails, the regenerated worms were supposed to become willing again faster than worms that had never been trained.

Supposed to.

A graduate student had tried a practice run that morning. Maya had watched from behind a line of tape on the floor. The regenerated worm had curled in the start chamber like a damp question mark and refused to go anywhere.

The curator had frowned and said, "Maybe skip the memory part. Regeneration is enough."

Maya had put that sentence into the running list in her head, under things that do not make sense yet.

Now visitors were arriving. Their voices filled the hallway, bouncing off glass. The curator reappeared, pinned crooked badges to her own sweater, and saw Soren writing.

"Are you making the sign less punchy?" she asked.

"More true," Soren said.

The curator winced. "Truth is wonderful, but the tour starts in six minutes."

Maya was looking at the practice maze. "Where is the rough floor?"

"In the training dish," the curator said. "This is the display maze. Clear bottom. Easier for visitors to see."

Maya did not answer. She picked up the empty training dish from the side bench. Its bottom was cloudy, scratched into a fine gray frost.

Soren looked from the dish to his notes. "The packet says rough-floored environment. Not just light. Not just food. Rough floor, light, food."

"They learned the whole room," Maya said.

"Not room. Conditions," Soren said, but his voice had changed.

The curator looked at the door, then at the worms, then at the visitors. "We cannot rebuild an apparatus in six minutes."

"We do not have to," Maya said.

Soren was already moving. Not fast like panic. Fast like steps in the right order. He opened the drawer labeled inserts and lifted out thin rectangles of textured plastic used for grip trials. He placed one under the clear maze, then stopped.

"Too low," he said. "They will not touch it."

Maya found the roll of transparent film used to line dishes. She pressed a square onto the textured plastic and rubbed until the bumps showed through, faint as fingerprints. Soren trimmed it with lab scissors and slid it into the bottom of the Y-maze.

"It has to be wet," he said.

Maya used a pipette to spread pond water across the film. The water beaded, then settled.

The curator opened her mouth, shut it, and handed Maya a fresh pipette.

"Careful," she said. "They tear if the water drops too hard."

Maya lowered the pipette until the tip touched the water and let one regenerated planarian slide out. It landed without a splash, a pale brown dash with a new triangular head.

The visitors crowded behind the tape. A little boy in a rocket shirt whispered, "Is that the whole animal?"

"Now it is," Soren said.

The lamp clicked on.

The planarian flattened. Its head waved left, right, left. For a moment it did nothing at all.

Maya held her breath because everyone else was breathing too loudly.

Then the worm moved.

Not quickly. Not like an arrow. Like a tiny scrap of night deciding against the dark. It slid forward over the rough film, stopped at the fork, swept its head along one wall, and took the branch toward the food.

A sound went through the visitors. Not applause. Smaller. Better.

The curator bent so close her badge swung into the glass.

"Run a naive one," Soren said.

Maya nodded. The comparison mattered. Without it, the first worm was only a worm going somewhere.

They rinsed the maze. Soren changed the film. Maya placed a planarian from the dish marked untrained. The lamp clicked. The new worm curled away from the light and pressed itself against the start wall.

The little boy in the rocket shirt whispered, "Maybe it is shy."

"Maybe," Maya said.

Soren looked at the timer. "Or maybe it has not met this problem before."

They ran another regenerated worm. It hesitated, then crossed. Another untrained worm refused. Another regenerated worm made a wrong turn, backed up, and found the food.

By the fourth trial, the curator had taken down the shiny sign.

Maya watched the dish of regenerated planarians. Each one had grown from a piece. Each new head had built eyespots, nerves, a mouth in the middle of the body, all the soft machinery of being one animal again. The old head was gone. The trained brain was gone. Still, something from before had not behaved as if gone.

Soren had stopped writing. His pencil hovered above the page.

"Where was it?" he asked.

Maya knew he did not mean the worm.

The curator answered too quickly. "There are hypotheses. Body-wide changes. Nerve tissue. Chemical signals. Maybe stem cells carry states we do not understand. We do not say memory exactly. We say evidence of retained learned behavior."

"That is not smaller," Soren said.

The curator looked at him. This time she was not hurrying.

"No," she said. "It is not."

Maya picked up the old sign and turned it around. The blank back was clean except for two fingerprints and a tiny smear of pond water.

"We need a better one," she said.

"Less punchy?" asked the curator.

"More dangerous," Maya said.

Soren wrote one sentence on a card in thick black marker. He showed it to Maya. She crossed out one word, replaced it with a smaller one, and nodded.

The next tour group came in talking, then quieted when they saw the lamp, the tiny maze, and the row of dishes with lids like little moons.

Maya placed the first regenerated worm at the start.

Beside the maze, Soren slid the card into the holder.

WHERE WAS THE LEARNING WHILE THE HEAD WAS GONE?