"It was not my imagination!" snapped Mrs. Chatham. "I know the symptoms of eyestrain when I see them, I guess. You'll have to stop Harry using that thing so much, or else be prepared to buy him glasses."
"All right, Sally," said Mr. Chatham wearily. "I'll see if I can't persuade him to be a little more moderate."
He went slowly into the living-room. At the moment, Harry was not using the microscope; instead, he seemed to be studying one of his cryptic pages of notes. As his father entered, he looked up sharply and swiftly laid the sheet down—face down.
Perhaps it wasn't all Sally's imagination; the boy did look nervous, and there was a drawn, white look to his thin young face. His father said gently, "Harry, Mother tells me she saw you blinking, as if your eyes were tired, when you were looking into the microscope today. You know if you look too much, it can be a strain on your sight."
Harry nodded quickly, too quickly, perhaps. "Yes, Dad," he said. "I read that in the book. It says there that if you close the eye you're looking with for a little while, it rests you and your eyes don't get tired. So I was practising that this afternoon. Mother must have been watching me then, and got the wrong idea."
"Oh," said Henry Chatham. "Well, it's good that you're trying to be careful. But you've got your mother worried, and that's not so good. I wish, myself, that you wouldn't spend all your time with the microscope. Don't you ever play baseball with the fellows any more?"
"I haven't got time," said the boy, with a curious stubborn twist to his mouth. "I can't right now, Dad." He glanced toward the microscope.
"Your rotifers won't die if you leave them alone for a while. And if they do, there'll always be a new crop."
"But I'd lose track of them," said Harry strangely. "Their lives are so short—they live so awfully fast. You don't know how fast they live."
"I've seen them," answered his father. "I guess they're fast, all right." He did not know quite what to make of it all, so he settled himself in his chair with his paper.