the weird mystery gathering about him. He stepped nearer the sphere. It was curiously like a miniature world. The irregular bluish areas would be seas; the green and the brown spaces land. In some parts, the surface appeared mistily obscured—perhaps, by masses of cloud.

Larry saw an odd-looking lamp, set perhaps ten feet behind the slowly spinning, floating ball, throwing upon it a bright ray of vividly blue light. Half the strange sphere was brilliantly illuminated by it; the rest was in comparative darkness. That blue lamp, it came to Larry, lit the sphere as the sun lights the earth.

"Nonsense!" he muttered. "It's impossible!"

Aroused by the seeming wonder of it, he was drawn nearer the ball. It spun rather slowly, Larry noted, and each rotation consumed several seconds. He could distinguish green patches that might be forests, and thin, silvery lines that looked like rivers, and broad, red-brown areas that must be deserts, and the broad blue stretches that suggested oceans.

"A toy world!" he cried. "A laboratory planet! What an experiment—"

Then his eyes, looking up, caught the glistening, polished lens of a powerful magnifying glass which hung by a black ribbon from a hook on one of the heavy steel beams which supported the huge mass of silently whirring apparatus.

Eagerly, he unfastened the magnifier. Holding it before his eyes, he bent toward the strange sphere spinning steadily in the air.

"Suffering shades of Caesar!" he ejaculated.

Beneath the lens a world was racing. He could see masses of vividly green forest; vast expanses of bare, cracked, ocherous desert; wastes of smooth blue ocean.

Then he was gazing at—a city?

Larry could not be sure that he had seen correctly. It had slipped very swiftly beneath his lens. But he had a momentary impression of tiny, fantastic buildings, clustered in an elflike city.

A pygmy planet, spinning in the laboratory like a world in the gulf of space! What could it mean? Could it be connected with the strange call from Agnes, with the blood on the floor, with the strange and ominous silence that shrouded the deserted room?

"Oh, Larry!" a clear, familiar voice rang suddenly from the door. "You came!"

Startled, Larry leaped back from the tiny, whirling globe and turned to the door. A girl had come silently into the room. It was Agnes Sterling. Her dark hair was tangled. Her small face was flushed, and her brown eyes were wide with fear! In a white hand, which shook a little, she carried a small, gold-plated automatic pistol.

She ran nervously across the wide floor to Larry, with relief dawning in her eyes.

"I'm so glad you came!" she gasped, panting with excitement. "I started to call you on the phone, but then I was afraid it would kill you if you came! Please be careful! It may come back, any minute! You'd better go away! It just took Dr. Whiting!"

"Wait a minute," Larry put in. "Just one thing at a time. Let's get this straight. To begin with, what is it that might kill me, and that got the doctor?"

"It's terrible!" she gasped, trembling. "A monster! You must go away before it comes back!"

Larry drew a tall stool from beside one of the crowded tables and placed it beside her.

"Don't get excited," he urged. "I'm sure everything will be all right. Just sit down, and tell me about it. The whole story. Just what is going on here, and what happened to Dr. Whiting."

He helped her upon the stool. She looked up at him gratefully, and began to speak in a rapid voice.

"You see that little planet? The monster came from that and carried the doctor back there. And I know it will soon be back for another victim—for sacrifice!"

She had pointed across the great room, toward the strange little globe which hung between the pillars of red and violet light.

"Please go slow!" Larry broke in. "You're too fast for me. Are you trying to tell me that that spinning ball is really a planet?"

Agnes seemed a little more composed, though she was still flushed and breathing rapidly. Her small hand still gripped the bright automatic.

"Yes, it is a planet. The Pygmy Planet, Dr. Whiting called it. He said it was the great experiment of the century. You see, he was testing evolution. We began with the planet, young and hot, and watched it until it is now almost as old as Mars. We watched the change and development of life upon it. And the rise and decay of a strange civilization. Until now its people are strange things, with human brains in mechanical bodies, worshiping a rusty machine like a god—"

"Go slow!" Larry pleaded again. "I don't see—Did the doctor build—create—that planet himself?"

"Yes. It began with his work on atomic structure. He discovered that certain frequencies of the X-ray—so powerful that they are almost akin to the cosmic ray—have the power of altering electronic orbits. Every atom, you know, is a sort of solar system, with electrons revolving about a proton.

"And these rays would cause the electrons to fall into incredibly smaller orbits, causing vast reduction in the size of the atoms, and in the size of any object which the atoms formed. They would cause anything, living or dead, to shrink to inconceivably microscopic dimensions—or restore it to its former size, depending upon the exact wave-length used.

"And time passes far more swiftly for the tiny objects—probably because the electrons move faster in their smaller orbits. That is what suggested to Dr. Whiting that he would be able to watch the entire life of a planet, in the laboratory. And so, at first, we experimented merely with solitary specimens or colonies of animals.

"But on the Pygmy Planet, we have watched the life of a world—the whole panorama of evolution—"

"It seems too wonderful!" Larry muttered. "Could Dr. Whiting actually decrease his size and become a dwarf?"

"No trick at all," Agnes assured him. "All you have to do is stand in the violet beam, to shrink. And move over in the red one, when you want to grow. I have been several times with Dr. Whiting to the Pygmy Planet."

"Been—" Larry stopped, breathless with astonishment.

"See the little airplane," Agnes said, pointing under the table.

Larry gasped.

Beneath the table stood a toy airplane. The spread of its glistening, perfect wings was hardly three feet. A wonderful, delicate toy, accurate in every detail of propeller, motor and landing gear, of brace and rudder and aileron. Then he realized that it was no toy at all, but a faithful miniature of a commercial plane. A complete, tiny copy of one of the latest single-motor, cabin monoplane models.

"It looks like it would fly," he said "a friend of mine his a big one, just like it! Taught me to fly it, last summer vacation. This is the very image of it!"

"It will fly!" Agnes assured him, now composed enough to smile at his amazement. "I have been with the doctor to the Pygmy Planet in it.

"You stand in the violet ray until you're about three inches high," she explained, "and then get into the plane. Then you fly up and into the violet ray at the point where it touches the planet, and remain there while you grow smaller. When you are the right size, all you have to do is drop to the surface, and land. To come away, you rise into the red ray and stay in it till you grow to proper size, when you come down and land."

"You—you've actually done that?" he gasped. "It sounds like a fairy story!"

"Yes, I've done it," she assured him. Then she shuddered apprehensively. "And the things—the machine-monsters, Dr. Whiting called them—have learned to do it, too. One of them came down the red ray, and attacked him. The doctor had a gun—but what could he do against one of those?" She shivered.

"It carried him back up the violet beam. Just a few minutes ago, I started to