The old man's eyes were shadowed with grim foreboding. "I have ordered something to refresh you and your companion," he said. "Eat first, my friends. We will talk later."

The six body-guards left the main cavern. Presently they returned with large trays made of fanlike leaves resembling the palmetto. Fresh fruits and uncooked vegetables formed the bulk of the meal. In silence they ate. After the litter had been cleared away the guards withdrew with the exception of the giant red ape, who crouched near the opening to the tunnel.

"I am glad you have come," began the old chieftain, "but sorry, too.

Our planet, or rather the higher forms of life upon it, are doomed."

Again there came to the ears of the earth people that far-off beat of sound that seemed to shake the ground. They looked to the white bearded leader for explanation.

"Ah, you hear it too," murmured the other. "For centuries, we of the great tribe of Esau have fought for the supremacy of our little world--ever since the Great One appeared in our midst and instructed us in world knowledge."

"And this Great One, as you call him," spoke Carruthers. "Who was he?"

"He was from your world. I never saw him. He comes to me as a legend.

For years he toiled among us, teaching and instructing until we mastered his language. He called himself Dahlgren. Later he ruled all the tribes. We of the Esau line he made into leaders because of our higher intelligence. The tribes of Zaku were trained for war. Perhaps you have noticed the chief of all the Zakus. He is crouching now beside the entrance to our inner walls. He is Marbo, and his followers live in the jungles."

"And does he talk as you do?"

The white chieftain shook his head. "No. Only we of the Esau tribe have mastered speech. Not counting the women of our tribe that comprise our numbers we are only seven in all."

"I owe Marbo my life as does also my companion," said Carruthers.

"Marbo looks upon you earth people as G.o.ds," spoke the old chieftain.

"He and his followers will protect you with their lives."

"And who rules over and beyond?" questioned Carruthers, waving his arm to cover the remaining portion of the electron.

"There is no rule beyond except that of force. The Great One called them by name, Morosaurus, Diplodocus, the Horned Ceratosaurus, and many others whose names I have long forgotten. They are our enemies whom we cannot destroy. And their numbers increase from year to year and are slowly backing us upon our last stronghold."

"Isn't there anything we can do?" asked Carruthers, feeling a quiver of apprehension along his spine.

Slowly, the old chieftain shook his head. "Nothing whatever. Marbo and his followers can control one or two, but when the herds begin to push on into our territory, we are doomed. Even now their rumblings and bellowings come through the jungles. Their thirst and hunger for flesh is enormous."

Carruthers turned upon the girl. "The old chief's words explain everything, Nan. Professor Dahlgren has been here and gone. He lived a lifetime in the span of a few hours earth-time. Now it looks as if we were destined to follow in his footsteps."

"I'm not afraid," said the girl. "Nothing can be worse than what we have already pa.s.sed through." And her eyes softened as she placed her small hands within those of Carruthers. "We have each other, Aaron."

He smiled rea.s.suringly and turned to the old chieftain. "I am Carruthers, a friend and a.s.sistant to Dahlgren. The girl here is Nanette."

The chieftain smiled gravely. "And I am Zark. Welcome to my kingdom, Carruthers and Nanette. We need you here. Now tell me of your world, for long have I waited for a follower of the great Dahlgren to appear before my people."

Throughout the remainder of the day Carruthers talked. The shafts of light paled at the end of the short day. Night came, bringing with it a sense of security against the increasing hordes that thundered and trumpeted beyond the borders of the jungle.

In the morning Zark instructed Marbo to remain close to Carruthers at all times. So the young scientist left the cavern and ascended the path leading to the top of the plateau. He looked at his watch and compared the second hand with the nucleus atom sailing across the heavens to estimate its speed.

Days pa.s.sed as he made his observations. Meanwhile he had searched and found the exact spot wherein he and Nanette had first stepped foot onto the electron. This spot he carefully marked off with a ring of huge boulders carried up by the followers of Marbo. Then he began to calculate upon his pad. There must be no mistakes. He and Nanette must be within the magic circle at the estimated time.

Between times he helped Nanette construct their living quarters in the cavern. Zark had furnished them with skins and furs with which to cover the walls. Carruthers made a fireplace of stones and restored the lost art of fire to Zark, Marbo and their followers.

Days slipped by like minutes. Short days filled with excursions into the jungles. Carruthers' face soon bristled with a stubble of beard.

This lengthened with time. Sharp thorns tore their clothes to ribbons.

Nanette, womanlike, cried many times during the nights because of the lack of a mirror and a comb for her untidy hair.

But other and more important events soon claimed the attention of the earth people. Day by day the herds of dinosaurs and other monsters of like breed edged closer and closer to the tiny civilization around the plateau. It worried Carruthers so much that he sought out Zark and had him bring the other six members of his tribe together for a council of war.

"A complete defensive system, Zark," he told them. "We must make a fortress of the plateau and fill the caverns with food."

Zark shook his head. "No. It is quite useless. Followers of Marbo have recently returned from over the beyond and report strange things. I have hesitated to speak of them for fear of alarming you. Our planet is breaking up. Violent eruptions have caused fires of stone and mud.

The rumblings you have heard were not made entirely by our enemies.

They came from the ground.

"An earthquake," murmured Carruthers, momentarily stunned by the news.

"But they are always of short duration, Zark. We have them on our own planet."

"Ah, but these are different. They cover the whole of our globe. The great Dahlgren noted them while he was with us. He wrote many words and figures on paper concerning them. Only yesterday I unearthed these records. The life of our planet was doomed to destruction during the present year. What matter if the herds of dinosaurs overrun us and destroy lives? In the end they, too, will be destroyed. It is fate. We can do nothing."

Even as the old chieftain spoke a gigantic rumbling, greater in intensity than any heretofore, shook the electron. Above the deep rolling disturbance underground rose the shrill cries of the apemen.

Carruthers leaped to his feet and raced through the tunnel. A herd of dinosaurs choked the path leading to the outside entrance. Marbo brushed past him, shrilling in great excitement.

"Drive them away!" ordered Carruthers. "Like this!" He hurled a rock at the eye of the nearest animal.

The dinosaur bellowed and backed away. The apes, and gorillas, used to fighting only with their long arms, caught on to the stunt with surprising quickness. Their powerful arms reached out. Stones and boulders began to hurtle from the mouth of the tunnel. They thudded against the heads of the great monsters like hailstones.

Subdued and frightened by this sudden display of force, the monsters withdrew down the path. But the apemen had discovered a new method of warfare. They found a childish delight in hurling stones. Within a few minutes the slope was barren of rocks. The animals followed up their momentary advantage and ran screaming down the path. The dinosaurs fled in panic.

AS soon as the enemy had been driven away, Carruthers pointed out to Marbo the advantage of gathering the stones up from the ground and returning them to the s.p.a.ce around the mouth of the tunnel so that he and his followers would be ready for a second repulse.

Zark appeared at this moment and helped with the explanation. His crafty old eyes turned with new respect upon the earthman.

Carruthers toiled with them every day from then on, building and fortifying the plateau against further incursions of the monsters.

Security and peace reigned for several weeks then hostilities broke out afresh.

The rumblings of the electron had increased with each pa.s.sing week.

Volcanic eruptions poured fresh discharges of molten lava and fiery sparks along the edges of the jungles.

"I don't want to needlessly alarm you, Nan," he told her that night, "but the fires have started. Zark was right. Unless we have rain before to-morrow morning the heat and smoke will drive us out into the open."

"But we can go to the top of the plateau," suggested the girl. "There aren't any trees--"