Aaron Carruthers hesitated for a bare fraction of a second. "Karl!" he whispered. "Our lives depend on him. Time flies fast for us, Nan.

Already it is growing light. But not on our earth. Karl still sits upon his chair staring incredulously at the miracle of our disappearing bodies. It will take weeks of time, as it affects us, for the initial shock to travel along his nerves to the center of his brain."

His voice shook with emotion quite contrary to his usual calm nature.

"Oh, I know it's hard to understand, Nan. I was a fool to meddle with laws of which I know so little compared to what there is yet to know."

"Then it's all true, Aaron. The little rat that came out from under the ray as an old rat was one and the same animal."

Carruthers nodded. "Time has changed in proportion to our size. We're moving so much faster than the earth that we must of necessity be bound to the universe of which we are now an integral part."

For a long time they remained silent, each immersed in dark, troubled thoughts. Nanette broke the silence.

"You don't suppose, Aaron, by any chance that Professor Dahlgren is still alive and on our planet?"

Carruthers shook his head negatively. "It's beyond human reason, Nan.

He was lost in the ray for over forty hours. Translated into minutes he's been gone twenty-four hundred minutes. Since the mouse we placed within the light ray aged approximately two years in the s.p.a.ce of one minute, Professor Dahlgren would, if he were alive, be about four thousand, eight hundred years old."

Nanette rose abruptly to her feet. "Oh bother the figures. My head's swimming with them. It's getting light now, and I'm hungry."

"Eat one of your food tablets," suggested Carruthers.

"Please don't get funny," said Nanette. "Karl has them in his coat pocket."

"Hum-m-m!" coughed Carruthers, following her example by rising to his feet. "Looks as though we'd have to rustle our food. I've got nothing on my person but a knife, a pencil, a fountain pen and some pieces of paper. Nothing very promising in any of them."

At that moment the sky became fused with reddish light. Over the horizon appeared a shining orb. Far-away hills and valleys leaped into sight. Then for the first time Carruthers noted the high plateau upon which he had spent the night. Had they ventured a hundred yards farther during the night they would have plunged into the rocky floor of a canyon a thousand feet below.

"Let's see if we can find a way down to the valley," he suggested. "If we get anything to eat it will have to come from trees. This plateau is barren of any form of vegetable matter."

They found a winding descent leading downward. It looked like a path that had been worn by the pa.s.sage of many feet.

"Someone's been here before us," he exclaimed. "The ground is too well worn to be accidental."

"Look! Look!" pointed Nanette. Her face had become pale from the excitement of her discovery. "What is it, Aaron?"

Carruthers bent forward to examine the strange footprint. It was nearly two feet across and divided in the center, as if the animal that made it had but two toes.

"From the size of the tracks and the length of the animal's stride, I should say it was some form of an amphibious dinosaur long extinct in our own world."

"Are they dangerous?"

"It all depends upon the species. Some of them are pure vegetarians; others are carnivorous. The heavy tramping we heard during the night evidently came from the beast who left these footprints."

They had come upon the footprints where the path made a turn, leading into a dense growth of trees and underbrush. And as Carruthers knelt beside the path he heard a rustle as of something moving directly behind him. Wonderingly, he turned his head to trace the disturbance.

But the woods seemed empty. "Strange," he murmured. "Did you hear something moving in back of us, Nan?"

Nan shook her head. "You don't think we're in any danger from these beasts, do you?"

Carruthers said nothing for the moment. Instead, he looked sharply in all directions and saw nothing. "Let's push on till we come to some kind of a shelter. Perhaps we'll find people much like ourselves."

Down the path they hurried, glancing curiously right and left at unknown flowers and trees. A bird with brilliant feathers skimmed above their heads, uttering shrill cries. Other voices from the birds and animals in the woods took up the cry. The woods grew denser as they pushed into the unknown.

In the woods at their right a rodent squeaked as some larger animal pounced upon it. Presently they came to a pool of water roughly seventy feet across. While they knelt to quench their thirst they saw two young deer eyeing them from the far side. Soft feet pattered behind the kneeling couple. Carruthers half whirled as he rose to his feet and peered into the jungle behind him.

A blur of reddish brown vanished behind a tree. Man or animal Carruthers couldn't determine. He grasped Nanette by the arm and pulled her back to the path.

"Quick!" he whispered. "There's someone or something following us. I'm sure of it now."

Nanette's voice trembled slightly. "What is it, Aaron?"

"I don't know." He turned his head again. This time he saw the thing that was following. A low e.j.a.c.u.l.a.t.i.o.n of alarm escaped his lips. A gigantic ape! The mouth of the creature sagged grotesquely, revealing two rows of yellow fangs. And its orange colored eyes were burning coals set close together. Carruthers sucked in a deep breath.

"Run, Nan," he gritted. "I'll try and scare him away."

Simultaneously with the scream of fright from the startled girl, a huge mountain of grayish flesh and bones blocked the downward slope of the path. Carruthers paled as he turned and faced the new menace.

Coming directly toward them he saw an immense animal so great in size that it seemed to shut out the light. A prehistoric dinosaur! It came slowly and leisurely, swinging its great red mouth from side to side.

Other denizens in the woods, sensing the presence of the huge killer, fled in a panic of alarm. Their shrill cries increased the terror that froze the hearts of the two earth people.

Nanette clung to her companion in abject terror, unable to move. Her fear stricken eyes were wild and staring as the mountain of flesh pushed towards them.

The animal's long neck arched far in front of its body, and its long, pointed tail remained out of sight within the trees.

Carruthers backed off the path into the underbrush, dragging the girl after him. The jaws of the huge animal opened wide with antic.i.p.ation.

Lumberingly he turned from the path and followed. Trees crashed before its gigantic bulk. The woods became a bedlam of snapping branches.

The horrified scream of the girl ended in a gurgling sigh. She toppled to the ground in a dead faint. Carruthers flung himself beside her crumpled body and gathered it into his arms. A quick glance he threw at the spot where he had last seen the gigantic ape. The animal was no longer there. It had disappeared.

The man's lips became a hard, straight line. Even as he straightened to his feet the leaves and branches of an overturned tree whipped his face. The red mouthed dinosaur was perilously near. So close that Carruthers could smell its great, glistening body. The odor was musky and foul.

Stumbling blindly he attempted to widen the distance between himself and his pursuer. But the hungry dinosaur pounded steadily on its course. There was no getting away from it. Its beady eyes sought out its prey and its keen smell told it exactly where the earth beings were.

On and on staggered Carruthers. The extra burden of the girl hampered his movements. Unseen roots tripped him time and time again. Each time he scrambled to his feet and picked up the unconscious girl. Briars tore at his clothing and stung his hands.

The underbrush was thickening. A warm, dank smell clung to the vegetation now almost tropical in nature. Beads of sweat rolled down the man's forehead and into his eyes. But the horrible fear of those red, dripping jaws spurred him to renewed efforts.

He doubled to the left, hoping to throw the animal off his tracks. The undergrowth seemed to thin out at this point. Renewed hope flowed through the young scientist's blood. He stumbled on blindly, scarce watching where his feet were taking him. A sigh of relief came to his lips. Ahead of him he saw a clearing. His stride lengthened and he broke into a shambling run.

Then it was he saw, towering walls rising up on both sides of him--steep walls that he could never scale, even if alone. He tried to change his course, but the huge bulk of the pursuing dinosaur effectively blocked his path. There was no alternative but to push on and pray for an opening in the rugged cliffs.