“Perhaps,” said Vale. “Their brain activity is not an important part of the process; I haven’t paid any particular attention to it.”

Kira stepped forward again. “They never wake up?”

“What would be the point?” asked Vale. “I can tend them more easily in their sleep—they’re far less trouble this way.”

“You don’t ‘tend’ them,” said Kira. “They’re not plants.”

“By strict biological definition, no, but the metaphor is apt.” Vale walked toward one, checking the tubes and wires that connected him to the apparatus in the ceiling. “They are not plants, but they are a garden, and I tend them carefully to harvest the crop that keeps the human race alive.”

“The pheromone,” said Kira.

“The technical name is Particle 223,” said Vale, “though I’ve taken to calling it Ambrosia.” He smiled. “The food of life.”

“You can’t do this,” Kira found herself saying.

“Of course I can.”

“Of course you can, but . . . we’d always known this was a possibility, but . . . it’s not right.”

“Tell that to the thousands of lives they’ve saved, and the hundreds more they’ll save this year alone.” Vale’s smile faded, and his face grew solemn. “Ten for two thousand, that’s two hundred lives each. We should all be so benevolent.”

“But . . . they’re slaves,” said Kira. “They’re worse than slaves, they’re . . . your creepy human garden.”

“Not human,” said Vale firmly, “things. Living things, yes, but mankind has used living things as tools since his first sentient thought. A bush in the wild is simply a bush—under human care it becomes a hedge, a wall to keep us safe. Berries become inks and dyes, mushrooms become medicine. Cows give us milk and meat and leather, horses pull our plows and carriages. Even you used horses to cross the toxic wasteland, a job I’m sure they would never have chosen on their own.”

“That’s different,” said Kira.

“Not different at all,” said Vale. “A horse, at least, is a part of the world. They exist today because a million years of natural selection failed to kill them: They earned their right to live. The Partials were grown in a lab, made by and for the aid of humanity. They’re . . . seedless watermelons, or blight-resistant wheat. Don’t let their human faces fool you.”

“It’s not just their faces,” said Kira hotly, “it’s their minds. You can’t talk to one and tell me they’re not real people.”

“Even computers could talk, by the end,” said Vale. “That didn’t make them people either.”

Kira shook her head, closing her eyes in anger and frustration. She was so repulsed by the revelation she could barely think. “You have to free them.”