microscope; the black, gleaming thing still stood there, but he did not see any of the slides, and the papers were piled neatly together to one side. His eyes fell on the fish bowl; it was empty, clean and shining. He knew Harry hadn't done those things; that was Sally's neatness.

Abruptly, instead of going straight up the stairs, he moved to the table and looked down at the pile of papers. The one on top was almost blank; on it was written several times: rty34pr ... rty34pr.... His memory for figure combinations served him; he remembered what had been written on another page: "rty34pr is the pond."

That made him think of the pond, lying quiescent under its green scum and trailing plants at the end of the garden. A step on the stair jerked him around.

It was his wife, of course. She said in a voice sharp-edged with apprehension: "What are you doing down here? Harry wants you. The doctor hasn't come; I phoned him just before I called you, but he hasn't come."

He did not answer. Instead he gestured at the pile of papers, the empty fish bowl, an imperative question in his face.

"I threw that dirty water back in the pond. It's probably what he caught something from. And he was breaking himself down, humping over that thing. It's your fault, for getting it for him. Are you coming?" She glared coldly at him, turning back to the stairway.

"I'm coming," he said heavily, and followed her upstairs.

Harry lay back in his bed, a low mound under the covers. His head was propped against a single pillow, and his eyes were half-closed, the lids swollen-looking, his face hotly flushed. He was breathing slowly as if asleep.

But as his father entered the room, he opened his eyes as if with an effort, fixed them on him, said, "Dad ... I've got to tell you."

Mr. Chatham took the chair by the bedside, quietly, leaving his wife to stand. He asked, "About what, Harry?"

"About—things." The boy's eyes shifted to his mother, at the foot of his bed. "I don't want to talk to her. She thinks it's just fever. But you'll understand."

Henry Chatham lifted his gaze to meet his wife's. "Maybe you'd better go downstairs and wait for the doctor, Sally."

She looked hard at him, then turned abruptly to go out. "All right," she said in a thin voice, and closed the door softly behind her.

"Now what did you want to tell me, Harry?"

"About them ... the rotifers," the boy said. His eyes had drifted half-shut again but his voice was clear. "They did it to me ... on purpose."

"Did what?"

"I don't know.... They used one of their cultures. They've got all kinds: beds of germs, under the leaves in the water. They've been growing new kinds, that will be worse than anything that ever was before.... They live so fast, they work so fast."

Henry Chatham was silent, leaning forward beside the bed.

"It was only a little while, before I found out they knew about me. I could see them through my microscope, but they could see me too.... And they kept signaling, swimming and turning.... I won't tell you how to talk to them, because nobody ought to talk to them ever again. Because they find out more than they tell.... They know about us, now, and they hate us. They never knew before—that there was anybody but them.... So they want to kill us all."

"But why should they want to do that?" asked