“I tell you I’m not crazy,” insisted the tall man. “Durkin, they got a big mine.”

Bill Durkin laughed roughly, and sneered openly at his partner, Frank Maget. “G’wan, you’re drunk.”

“Well, I was last night,” admitted Maget. “But I’d slept it off this morning. I was lying under that table in the Portuguee’s, and when I opened my eyes, there were these three birds sitting near me. They hadn’t spotted me. I heard ‘em talking of wealth, how their mine was of unbelievable richness and greater than any other deposit in the world. Well, that means something, don’t it?”

“That’s all right,” said Durkin. “But whoever saw a cricket fifteen inches long?”

[Illustration: Its form was that of a gigantic frog, and from its throat sounded the terrific bellowing which rivaled thunder.]

“Listen. There were three of these guys. One was a hell of a looking fellow: his face was piebald, with purple spots. His skin was bleached and withered, and one eye looked like a pearl collar button! They called him Professor, too, Professor Gurlone. Well, he takes out this damn cricket thing and it was sort of reddish purple but alive, and as long as your forearm. This professor guy says his son had taken an ordinary cricket and made it grow into the one he had. But the mine was what interested me. I kept my mouth shut and my ears open, and it’s in the Matto Grosso. May be emeralds, diamonds, or gold. Boy, I’m heading for it, right now. The old guy’s going back to-morrow, get me?”

“It’s a lot of bunk,” growled Durkin, who was stout and red of countenance.

“Yeh? Well, Otto Ulrich don’t put fifty thousand into bunk.”

Durkin whistled. “You mean the German loosened up that much?” he asked, and his eyes showed interest.

“Sure. He paid this Gurlone fifty thousand dollars--credit, of course.”

“Well--maybe there’s something in the mine story. But boy, you were drunk when you saw that cricket. No cricket ever grew that big. You always see things when you get too much rum in you.”

“The hell you say,” cried Maget. “I saw it, I tell you!”

Durkin feigned elaborate politeness. “Oh, all right, Frank. Have it your own way. You saw a cricket that big and this Gurlone feller took a couple of pink elephants out of his pocket to pay the check. Sure, I believe you.”

But money never failed to attract the two tropical tramps. They were looking for trouble, not work, and the idea of a raid on a rich mine in the Matto Grosso was just what they would enjoy.

An hour later, they had cornered a small, inoffensive peon named Juan. Juan, Maget and Durkin had discovered, had come out of the wilderness with Professor Gurlone, the strange looking gentleman who spoke of a fabulously wealthy mine and commanded checks for fifty thousand dollars from a reputable banking firm. Such a man was worth watching.

The two rascals were expert at pumping the little half-breed. They knew peons, and the first thing that happened was that Durkin had slipped Juan several dollars and had pressed a large glass of whiskey on the little man.

The conversation was in broken English and Spanish.

“Quien sabe?”

Durkin and Maget had this phrase flung at them often during the course of the talk with Juan, and there were many elaborate shrugs.

There was a mine, way back in the Matto Grosso, said Juan. He thought it might contain silver: there had been the shaft of an old mine there. But now they were deep down in the ground, digging out reddish brown ore, and the cavern smoked and smelled so badly a man could work but an hour or two before being relieved. But the pay was very high. Also, Juan, in his rambling way, spoke of grotesque animals. What were these creatures like? asked Durkin. Then came a shrug, and Juan said they were like nothing else on earth.

Durkin discounted the part of the story having to do with the strange animals. He thought it was peon superstition. But now he was sure there was a rich mine to be raided.

“It’s a tough part of the Grosso,” he said, turning to Maget.

“Sure. Hard to carry enough water and supplies to make it. Say, Juan, who was that big Portuguee with Professor Gurlone? He’s blind, ain’t he? His eyes were white as milk, and his face tanned black as river mud. Surely is a great big guy, and tough looking, too.”

Durkin drummed on the table, considering the matter, while Juan spoke of the big Portuguese. The swarthy man with the colorless blind eyes was Espinosa, former owner of the mine. He had sold part of his claim to the Gurlones, but had remained with them as an assistant. Though blind, he knew the depths of the mine and could feel his way about, and direct the peons in their labors.

“I’ve got it,” said Durkin, turning back to Juan and Maget. “Juan, it’s up to you. You’ve got to blaze the trail so we can follow you in. And you can steal food and cache it for use on the way, see? We’ll come along a day or so after the Gurlones.”

It took some persuading to make Juan consent to their plot, but the peon yielded at last to money and the promise of part of the spoils. “Maybe you can steal Gurlone’s samples and they’ll give us a line on what he’s up to out there. Whether it’s emeralds or diamonds or gold that they’re taking out of the mine.”

Juan was stupid and superstitious, like most of his fellows. He had obeyed orders, digging out the red ore, and that was all he knew. But prompted by the two tramps, he was ready for trouble, too.

Juan told them that Professor Gurlone carried a small lead case which he seemed to prize greatly.

“Get it, then,” ordered Durkin.

The two tramps saw Gurlone’s party start on the morrow. There were many cases of supplies loaded into launches, some marked Glass, Acids, and so on. Then there were boxes of food and various things needed in a jungle camp.

Juan, their tool, was working with the other peons, and at ten o’clock in the morning the launches set out, pushing into the current of the Madeira.

Old Gurlone, of the livid face, was in charge of one boat, and the gigantic Portuguese, with his colorless eyes and burned complexion, sat beside him.

That night, the two tropical tramps stole a small boat with a one-cylinder motor, and started up the river.

It was a hard journey, but they were used to river and jungle work, and the object they had in view was enough to make them discount trouble. They speculated upon what manner of treasure it was they would find in the cavern of the Matto Grosso mine. It might be precious stones, it might be gold. Certainly it was something very valuable.

They carried little supplies, but they were heavily armed. For food, they might hunt and also depend on the caches left by their friend, Juan the peon.

Three hundred miles from Manaos, they came to the landing where old Gurlone had unloaded his boats. The two tramps drew their own craft up on shore a quarter of a mile away, keeping out of sight, and hid the boat in dense brush. Then they crept up the river bank, keeping out of sight of the boatmen, who were preparing for the return voyage, and cut into the jungle so as to strike the trail of the caravan ahead.

For several hours they followed the path easily. They found palm trees blazed with new marks, and these they were sure their friend Juan had left for them. But the trail was easy to keep without these. The supplies had been loaded on burros, which had been awaiting the boats.

That night, they camped beside a small stream. They were but twenty-four hours behind Professor Gurlone and his party, and the food Juan had cached for them was in good condition.

They were up at daybreak, and pressed on, armed to the teeth and ready for a fight.

“What’s that?” said Durkin, stopping so suddenly that Maget ran into him.

They had been walking at a swift pace along the jungle path, the giant trees forming a canopy overhead. Monkeys screamed at them, birds flitted a hundred feet above them in the roof of the forest.

The sun beat on the jungle top, but few rays lightened the gloom beneath.

From up ahead sounded a frightful scream, followed by a long drawn out wailing. Maget glanced at Durkin, and the latter shrugged, and pressed on. But he gripped his rifle tightly, for the cries were eery.

From time to time the two stopped to catch better the direction of the wails. At last, they located the spot where the injured person lay.

It was under a great bombax tree, and on the shaded ground writhed a man. The two stopped, horrified at the squirming figure. The man was tearing at his face with his nails, and his countenance was bloody with long scratches.

He cursed and moaned in Spanish, and Durkin, approaching closer, recognized Juan the peon.

“Hey, Juan, what the hell’s the matter? A snake bite you?”

The bronzed face of the sturdy little peon writhed in agony. He screamed in answer, he could not talk coherently. He mumbled, he groaned, but they could not catch his words.

At his side lay a small lead container, and closer, as though he had dropped it after extracting it from its case, lay a tube some six inches in length. It was a queer tube, for it seemed to be filled with smoky, pallid worms of light that writhed even as Juan writhed.

“What’s the trouble?” asked Durkin gruffly, for he was alarmed at the behavior of the peon. It seemed to both tramps that the man must have gone mad.

They kept back from him, with ready guns. Juan shrieked, and it sounded as though he said he was burning up, in a great fire.

Suddenly the peon staggered to his feet; as he pushed himself up, his hands gripped the tube, and he clawed at his face.

Perplexity and horror were writ on the faces of the two tramps. Maget was struck with pity for the unfortunate peon, who seemed to be suffering the tortures of the damned. He was not a bad man, was Maget, but rather a weakling who had a run of bad luck and was under the thumb of Durkin, a really hard character. Durkin, while astounded at the actions of Juan, showed no pity.

Maget stepped forward, to try and comfort Juan; the peon struck out at him, and whirled around. But a few yards away was the bank of the stream, and Juan crashed into a black palm set with spines, caromed off it, and fell face downward into the water. The glass tube was smashed and the pieces fell into the stream.

“God, he must be blind,” groaned Maget. “Poor guy, I’ve got to save him.”

“The hell with him,” growled Durkin. He grasped his partner’s arm and stared curiously down at the dying peon.

“Let go, I’ll pull him out,” said Maget, trying to wrench away from Durkin.

“He’s done for. Why worry about a peon?” said Durkin. “Look at those fish!”

The muddy waters of the stream had parted, and dead fish were rising about the body of Juan. But not about the dying man so much as close to the spot where the broken tube had fallen. White bellies up, the fish died as though by magic.

“Let’s--let’s get the hell back to Manoas, Bill,” said Maget in a sickly voice. “This--this is too much for me.”

A nameless fear, which had been with Maget ever since the beginning of the venture, was growing more insistent.

“What?” cried Durkin. “Turn back now? The hell you say! That damn peon got into a fight with somebody and maybe got bit by a snake later. We’ll go on and get that treasure.”

“But--but what made those fish come up that way?” said Maget, his brows creased in perplexity.

Durkin shrugged. “What’s the difference? We’re O. K., ain’t we?”

In spite of the stout man’s bravado, it was evident that he, too, was disturbed at the strange happenings. He kept voicing aloud the question in his mind; what was in the queer tube?

But he forced Maget to go on. Without Juan, the peon, to leave them caches of food on the trail, they would have a difficult time getting provender, but both were trained jungle travelers and could find fruit and shoot enough game to keep them going.

Day after day they marched on, not far from the rear of the party before them. They took care to keep off Gurlone’s heels, for they did not wish their presence to be discovered.

When they had been on the journey, which led them east, for four days, the two rascals came to a waterless plateau, which stretched before them in dry perspective. Before they came to the end of this, they knew what real thirst was, and their tongues were black in their mouths before they caught the curling smoke of fires in the valley where they knew the mine must be.

“That’s the mine,” gasped Durkin, pointing to the smoke.

The sun was setting in golden splendor at their backs; they crept forward, using great boulders and piles of reddish earth, strange to them, for cover. Finally they reached the trail which led to the hills overlooking the valley, and a panorama spread before them which amazed them because of its elaborateness.

It seemed more like a stage scene than a wilderness picture. Straight ahead of them, as they lay flat on their stomachs and peered at the big camp, yawned the black mouth of a large cavern. This, they were sure, was the mine itself. Close by this mouth stood a stone hut. It was clear that this building had something to do with the ore, perhaps a refining plant, Durkin suggested.

There were long barracks for the peons, inside a barbed wire enclosure, and they could see the little men lounging now about campfires, where frying food was being prepared. Also, there was a long, low building with many windows in it, and houses for supplies and for the use of the owners of the camp.

“Looks like they were ready in case of a fight,” said Durkin at last. “That fence around the peons looks like they might be havin’ trouble.”

“Some camp,” breathed Maget.

“We got to find somethin’ to drink,” said Durkin. “Come on.”

They worked their way about the rim of the valley, and in doing so caught glimpses of Professor Gurlone, the elderly man they had spotted in Manaos, and also saw the big Portuguese with his sightless eyes.

At the other side of the valley, they came on a spring which flowed to the east and disappeared under ground farther down.

“Funny water, ain’t it?” said Durkin, lying down on his stomach to suck up the milky water.

But they were not in any mood to be particular about the fluids they drank. The long dry march across the arid lands separating the camp from the rest of the world had taken all moisture from their throats.

Maget, drinking beside his partner, saw that the water glinted and sparkled, though the sun was below the opposite rim of the valley. It seemed that greenish, silvery specks danced in the milky fluid.

“Boy, that’s good,” Durkin finally found time to say, “I feel like I could fight a wildcat.”

The water did, indeed, impart a feeling of exhilaration to the two tramps. They crept up close to the roof of the parallel shaft which they had seen from the other side of the valley, and looked down into the camp again.

Professor Gurlone of the livid face and Espinosa the blind Portuguese, were talking to a big man whose golden beard shone in the last rays of the sun.

“That’s the old bird’s son,” said Durkin, “that Juan told us about. Young Gurlone.”

A rumbling, pleasant laugh floated on the breeze, issuing from the big youth’s throat. The wind was their way, now, and the valley breathed forth an unpleasant odor of chemicals and tainted meat.

“Funny place,” said Maget. “Say, I got a hell of a headache, Bill.”

“So’ve I,” grunted Durkin. “Maybe that water ain’t as good as it seemed at first.”

They lay in a small hollow, watching the activity of the camp. The peons were in their pen, and it was evident that they were being watched by the owners of the camp.

As purple twilight fell across the strange land, the two tramps began to notice the dull sounds which came to their ears from time to time.

“That’s funny thunder,” said Maget nervously. “If I didn’t know it was thunder, I’d swear some big frogs were around here.”

“Oh, hell. Maybe it’s an earthquake,” said Durkin irritatedly. “For God’s sake, quit your bellyachin’. You’ve done nothin’ but whine ever since we left Juan.”

“Well, who could blame me--” began Maget. He broke off suddenly, the pique in his voice turned to a quiver of fear, as he grasped Durkin’s arm. “Oh, look,” he gasped.

Durkin, seeing his partner’s eyes staring at a point directly behind him, leaped up and scrambled away, thinking that a snake must be about to strike him.

He turned round when he felt he was far enough away, and saw that the ground was moving near the spot where he had been lying.

The earth was heaving, as though ploughed by a giant share; a blunt, purplish head, which seemed too fearful to be really alive, showed through the broken ground, and a worm began to draw its purple length from the depths. It was no snake, but a gigantic angleworm, and as it came forth, foot after foot, the two watched with glazed eyes.

Maget swallowed. “I’ve seen ‘em two feet long,” he said. “But never like that.”

Durkin, however, when he realized that the loathsome creature could not see them and was creeping blindly towards them with its ugly, fat body creasing and elongating, picked up rocks and began to destroy the monstrous worm. He cursed as he worked.

Dull red blood spattered them, and a fetid odor from the gashes caused them to retch, but they finally cut the thing in two, and then they moved away from there.

The dull rumblings beneath them frightened Maget, and Durkin too, though the latter tried to brazen it out.

“Come on, it’s gettin’ dark. We can take a look in their mine now.”

Maget, whimpering, followed. The booming sounds were increasing.

But Durkin slipped down the hillside, and Maget followed into the valley. They crept past the stone shack, which they noticed was padlocked heavily.

Durkin stopped suddenly, and cursed. “I’ve cut my foot,” he said. “These damn shoes are gone, all right, from that march. But come on, never mind.”

They crept to the mouth of the cavern and peered in. “Ugh,” said Maget.

He drew back with a shudder. The floor of the mine was covered with a grey slush, in which were seething white masses of slugs weaving in the slime. A powerful, rotten odor breathed in their faces, as though they stood in the mouth of a great giant.

“Ah!” yelled Durkin, throwing his arms across his face.

The greenish, ghostly light which emanated from the slime was weaker than moonlight, just enough to see by; a vast shadow hovered above their heads, as though a gigantic bat flew there. The sweep and beat of great wings drove them back, and they fled in terror from such awful corruption.

But the flying monster, with a wing spread of eight feet, dashed past them, and silhouetted against the rising moon like a goblin. Then came another, and finally a flock of the big birds.

Durkin and Maget ran away, passing the stone house which stood near the cavern’s mouth. The booming sounds from the bowels of the earth filled their ears now, and it was not thunder; no, it issued from the depths of the mine.

“We--we got to get somethin’ to eat,” said Durkin, as they paused near one of the shacks, in which shone a light.

Sounds of voices came from the interior. They crept closer, and listened outside the window. Inside, they could see Espinosa, Gurlone senior, and the big youth with the golden beard, Gurlone junior.

“Yes, father,” the young man was saying. “I believe we had better leave, at once. It’s getting dangerous. I’ve reached the five million mark now, with the new process, and it is ready to work with or sell, just as we wish.”

“Hear that?” whispered Durkin triumphantly. “Five million!”

“It’s all ready, in the stone house,” said young Gurlone.

“Why should we leave now?” said old Gurlone, his livid face working. “Now, when we are just at the point of success in our great experiments? So far, while we have struck many creatures of abnormal growth, still, we have overcome them.”

“Well, father, there is something in the mine now which makes it too dangerous to work. That is, until they are put out of the way. You can hear them now.”

The three inside the shack listened, and so did Durkin and Maget. The booming sounds swelled louder and the earth of the valley shook.

“I t’ink we better go,” said Espinosa gruffly. “I agree with your son, Professor.”

“No, no. We can conquer this, what ever it is.”

“You see, father, while you were away, we broke through into a natural cavern, an underground river. It was then that the trouble started. You know the effect of the stuff on the insects and birds. It enlarged a cricket one hundred times. You saw that yourself. Six of the peons have disappeared--they didn’t run away, either. They went down the shaft and never came back.”

“Oh, they probably fell into the water and drowned,” said old Gurlone impatiently. “Even if they did not, we can kill anything with these large bore rifles.”

“We’d better pull out and let it alone for a while,” said young Gurlone gravely. “The peons have been trying to bolt for several days. They’d be gone now if I hadn’t penned them in and electrified the fence.”

Maget put his hand on his friend’s shoulder. “I’m starving,” he whispered.

Durkin nodded, and they turned away, toward what they had marked as a supply shack. They heard a low murmur from the peons’ pen, as they began to break off the hasps of the lock which held the door of the storehouse.

They got inside with little trouble, and began to feel about in the dark for food. They located biscuits and canned goods which they split open, and these they wolfed hungrily, listening carefully for sounds from outside.

“Here they come,” said Maget, gripping Durkin’s arm.

They looked out the window of the supply shack, and saw old Gurlone issue from the building outside which the two tramps had been listening. In one hand, the old Professor, brave as a lion, carried an old fashioned double-barreled elephant gun, and the rays from a powerful electric torch shone across the barrel.

At least, they thought the bizarre figure was old Gurlone, from the size. For the man was clad in a black, shiny suit, and over his head was a flapping hood of the same material in which were large eyeholes of green glass. Behind this strange form came a larger one, armed also with a big bore rifle and with another powerful flashlight.

The blind Portuguese was armed, too, but he was not clad in the black suit. He took his stand beside the mouth of the cavern, and waited while the two Gurlones entered the mine.

“My foot hurts,” said Durkin suddenly, breaking the silence.

“I’m going out and see what happens,” said Maget.

Durkin limped after Maget, who now took the lead. They crept close as possible to the mine opening, and saw the big Portuguese standing there in silence, listening carefully. Any sounds the two might have made were drowned in the great bellowing from within the cavern.

These noises, so like the croak of bullfrogs but magnified a thousand times, were terrifying to the heart.

The sweep of wings sounded on the night air, and Espinosa drew back and squatted close to the ground, as immense green creatures, flying on dusty wings, issued from the mine.

“God, those are moths,” breathed Maget.

Yes, unmistakably, they were moths, as large as condors. The green ones, but for their size, were lunar moths, familiar enough to the two tramps. More bats came, disturbed by the entrance of the two Gurlones.

Durkin broke, then. “I’m--I’m--I guess you’re right, Maget,” he whispered, in a terrified voice. “We should have never come. If my foot wasn’t hurt, I’d start for the river now. Curse it, what a place!”

The booming, vast croaks filled the whole valley, reverberating through the hills. Wails sounded from the peon camp.

The big Portuguese was shouting to the Gurlones. “Come out, come out!”

Maget gripped his own rifle, and stood up, bravely. His fear, though it was great, seemed to have brought out the better side of the man, while Durkin, so brave at first, had cracked under the strain.

“Look out, they’ll see you,” whimpered Durkin.

Maget strode forward. A blast of fetid, stinking air struck his face, and he choked. The noises were now ear-splitting, but above the bellows came the sounds of the big rifles, the echoes booming through the recesses of the cavern.

Then the two Gurlones, running madly, burst from the mine entrance.

“Run,” they screamed. “Run for your life, Espinosa!”

“I’ll help you,” cried Maget, and Durkin could detain him no longer.

The Gurlones hardly noticed the newcomer, as they ran madly towards the shelter of their houses. Espinosa joined them, going swiftly in spite of his blind eyes.

The croaking made Maget’s brain scream with the immensity of the sound. Luminous, white disks, three feet in diameter, glared at him, and the creature, which progressed with jerky leaps toward him, almost filled the mouth of the mine.

It was hot in pursuit of the fleeing Gurlones. It squatted and then jumped, and presently it was out in the night air.

Its form was that of a gigantic frog, but it stood some twenty feet in height, and from its throat sounded the terrific bellowing which rivalled the thunder.

Maget bravely stepped forward, and began to fire into the huge, soft body. The great mouth opened, and as the dum-dum bullets tore gashes in the blackish green batrachian, the thunderous croaks took on a note of pain.

The odor of the creature was horrible. Maget could scarcely draw his breath as he fired the contents of the magazine into the big animal. Two more jumps brought the frog almost to Maget’s feet, and the tropical tramp felt a whiskerlike tentacle touch his face, and bad smelling slime covered him.

The frog was blind, without doubt, from its underground life, but the tentacles seemed to be the way it finally located its prey, for it turned on Maget and made a final snap at him. The great jaws closed like the flap of hell, and Maget leaped back with a cry of triumphant terror.

The bullets had finally stopped the big frog, but at its heels came a strange, jellylike creature, not quite as bulky as the frog, but pushing along on its legs and with a tail some eight feet thick and fifteen feet in length. This, too, evidently a polywog, was blind, with whitened discs for eyes, but it slid along at a rapid rate because of its size. Maget’s gun was empty; he turned so flee, but the polywog stopped and sniffed at the thick blood of its fellow. Then, to Maget’s relief, it began to hungrily devour its companion.

Utterly filthy, and ferocious, the polywog in silence snapped great chunks from the dead giant frog.

“Hello. Who are you?”

Maget turned, having forgotten the amenities of life in the excitement. Professor Gurlone and his son, still clad in their black suits, but with their helmets off, were standing beside him, clutching their guns and lights.

The big Portuguese, Espinosa, appeared, and Durkin was beside him.

“Why,” said Maget, between gasps, “we just happened to be out exploring, and we saw your camp. We were on our way in when we heard the noises and came to investigate.”

“I see,” said old Gurlone. “What made you head in this direction, and where’s your outfit?”

“Oh, we cached most of it back there,” said Maget. “My partner’s hurt his foot, so he can’t walk well. Isn’t that so, Durkin?”

“Yeh,” growled Durkin. “I got a sore foot, all right.”

Old Gurlone was suspicious of the vague story which Maget and Durkin concocted as the explanation of their presence in the valley. But evidently the Professor was too worried about the situation in which he and his friends were, to question the two tramps very closely. In fact, he seemed rather glad that he had two more pairs of hands to aid him and he thanked Maget for his bravery.

They dispatched the great polywog as it tore its parent to bits, and then the five men, the two Gurlones, Espinoza, Maget, and the limping, cursing Durkin, retired to one of the shacks.

The living quarters of the Gurlones was quite elaborate. There were many books on rough shelves, and there was a small bench filled with glass phials and chemicals, though the main laboratory was in one of the long buildings.

Professor Gurlone poured drinks for the five, and welcomed Durkin and Maget as allies.

“We’ll need every man we can get, if we are to cope with these great creatures,” said old Gurlone. “The peons are too frightened to be of use. Luckily, it was a frog we came upon on the banks of the subterranean river. There is no telling how many more creatures of the same or greater size may be down there. We will have to destroy them, every one.”

Maget and Durkin shuddered. “Say,” blurted Durkin, his face working nervously, “how the hell did that frog get so big? I thought I was seein’ things, Professor.”

“No, no,” said Professor Gurlone. “You see, the ore in the mine contains radium, that is, salts of radium. It is a pitchblende deposit, and it happens to be so rich in radium content that throughout the ages it has affected all the life in the cavern. The arid land surrounding the ore--this has been, generally, one of the characteristics of radium deposits--has kept most of the jungle creatures away, but underground beings such as reptiles, worms and frogs, have gradually become immune to the effects of the ore and have grown prodigiously and abnormally under the stimulation of the rays given off by the radium.