Chatham sat down and bent over the microscope. Puzzled and a little hurt, he twirled the focusing vernier and peered into the eyepiece, looking down once more into the green water world of the rotifers.

There was a swarm of them under the lens, and they swam lazily to and fro, their cilia beating like miniature propellers. Their dark eyes stared, wet and glistening; they drifted in the motionless water, and clung with sucker-like pseudo-feet to the tangled plant stems.

Then, as he almost looked away, one of them detached itself from the group and swam upward, toward him, growing larger and blurring as it rose out of the focus of the microscope. The last thing that remained defined, before it became a shapeless gray blob and vanished, was the dark blotches of the great cold eyes, seeming to stare full at him—cold, motionless, but alive.

It was a curious experience. Henry Chatham drew suddenly back from the eyepiece, with an involuntary shudder that he could not explain to himself. He said haltingly, "They look interesting."

"Sure, Dad," said Harry. He moved to occupy the chair again, and his dark young head bowed once more over the microscope. His father walked back across the room and sank gratefully into his arm-chair—after all, it had been a hard day at the office. He watched Harry work the focusing screws as if trying to find something, then take his pencil and begin to write quickly and impatiently.

It was with a guilty feeling of prying that, after Harry had been sent reluctantly to bed, Henry Chatham took a tentative look at those papers which lay in apparent disorder on his son's work table. He frowned uncomprehendingly at the things that were written there; it was neither mathematics nor language, but many of the scribblings were jumbles of letters and figures. It looked like code, and he remembered that less than a year ago, Harry had been passionately interested in cryptography, and had shown what his father, at least, believed to be a considerable aptitude for such things.... But what did cryptography have to do with microscopy, or codes with—rotifers?

Nowhere did there seem to be a key, but there were occasional words and phrases jotted into the margins of some of the sheets. Mr. Chatham read these, and learned nothing. "Can't dry up, but they can," said one. "Beds of germs," said another. And in the corner of one sheet, "1—Yes. 2—No." The only thing that looked like a translation was the note: "rty34pr is the pond."

Mr. Chatham shook his head bewilderedly, replacing the sheets carefully as they had been. Why should Harry want to keep notes on his scientific hobby in code? he wondered, rationalizing even as he wondered. He went to bed still puzzling, but it did not keep him from sleeping, for he was tired.

Then, only the next evening, his wife maneuvered to get him alone with her and burst out passionately:

"Henry, I told you that microscope was going to ruin Harry's eyesight! I was watching him today when he didn't know I was watching him, and I saw him winking and blinking right while he kept on looking into the thing. I was minded to stop him then and there, but I want you to assert your authority with him and tell him he can't go on."

Henry Chatham passed one nervous hand over his own aching eyes. He asked mildly, "Are you sure it wasn't just your imagination, Sally? After all, a person blinks quite normally, you know."

"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