asked Maget.

"Exactly. The radio-activity of the elements in the ore give off the light. There are three rays, the alpha, beta and gamma, and--"

The professor forgot himself in a lecture on the properties of radium.

Durkin, breaking in, asked, slyly. "Is this radium worth as much as silver?"

Young Kenneth Gurlone laughed, and even old Professor Gurlone smiled.

"Radium is worth more than gold or diamonds or platinum. Its value is fabulous. We have five million dollars worth already, in the form of the chloride."

"Whew," whistled Durkin.

He glanced sidewise at Maget.

"Yes," said Professor Gurlone, "five million dollars worth of it!

Those great monsters who have been developed throughout the ages by the action of the radium rays on their bodies, causing them to grow so prodigiously, are but incidents. We must destroy them, so that our work cannot be interfered with. We must use dynamite, blow them to bits. They are powerful enough to crush the stone bank by the mine mouth and ruin the labors of the past two years, gentlemen."

Armed, and once more fortified with whiskey, the five made their way outside. The moon was darkened by an immense shadow, as one of the giant bats winged its way over their heads. But there were no more monster frogs. The ugly, bulky shapes of the dead polywog and its parent lay before them.

"We are safe for the moment," said Professor Gurlone. "Go and quiet the peons, Espinosa: they will listen to you."

The peons still wailed in terror; the blind Espinosa slipped silently away.

"Come," said Professor Gurlone, to his son and to Maget and Durkin. "I will show you the laboratory, so that you can understand better the effects of radium on growth."

The professor led them to the long, low, many-windowed building nearby, and flooded it with light. It contained cage after cage in which were monkeys, pumas, and various jungle folk. These creatures set up a chattering and howling at the light and intruders.

Maget glanced curiously about him. He saw shining vials and gla.s.sware of queer shapes on long black tables, and tubes of chemicals. There were immense screens of dull lead. "Those are for protection," said Professor Gurlone, "as are the lead-cloth suits we wear. Otherwise we would be burned by radium rays."

Maget looked about, to see if his partner was listening, but he had gone away.

However, Maget was intensely interested. He went from cage to cage as Professor Gurlone, rather in the manner of a man giving a lecture to students, pointed out animal after animal that had been treated by the radium.

"This," said the professor, "is a monkey which usually attains a height of two feet. You can see for yourself that it is now larger than a gorilla."

The horrible, malformed creature bared its teeth and shook its bars in rage, but it was weak, evidently, from the treatment accorded it. Its hair was burned off in spots, and its eyes were almost white.

There was a jaguar, and this beast seemed to have burst its skin in its effort to grow as large as three of its kind.

"You see, we have not so much time as nature," said Professor Gurlone.

"These beasts cannot be enlarged too rapidly, or they would die. They must be protected from the direct rays of the radium, which is refined. In the ore, the action is more gradual and gentle, since it is less concentrated. But the metal itself would burn the vital organs out of these creatures, cause them to be struck blind, shrivel them up inside and kill them in a few minutes in the quant.i.ty we have. We expose them bit by bit, allowing more and more time as they begin to grow immune to the rays. Here, you see, are smaller creatures which have grown some eight or ten times beyond normal size."

All the animals seemed the worse for wear. Maget, his brain reeling, yet was beginning to grasp what radium did to one. It was not gold that you could pick up and carry away.

"If a man touched that radium," he asked, "what would happen to him?"

"Just what I said would happen to the animals if we did not give it to them gradually," said Gurlone, with a wave of his hand. "It would kill him, strike him down as though by invisible poison gas. His heart and lungs would cease to function, pernicious anemia would set in, as the red corpuscles in his blood perished by millions. He would be struck blind, fall down and die in agony."

To Maget came the picture of the unfortunate Juan. As though answering his unasked question, Professor Gurlone went on. "We had a peon coming up with us," he said. "His name was Juan. He stole my sample-case, which contained an ounce of radium chloride, and ran off with it. If he opens it, it will kill him in just that way."

Maget shivered. "But--but didn't it hurt you to carry it?" he asked.

"No. For it was incased in a lead container some two inches in thickness, and the rays cannot penetrate such a depth of lead. They are trapped in the metal."

"Father, father, you're wasting time," broke in Kenneth Gurlone, shaking his yellow head. "We must act at once. The peons are almost mad with fear. Even Espinosa cannot quiet them. And every moment is precious, for the monsters may break forth."

But Maget was looking nervously about for Durkin. Where was he? Durkin had his mind on the treasure, and--

As they turned toward the door, the professor saying. "The rays from the ore, which is nor so concentrated as the purified metal, do not kill--" Durkin suddenly appeared.

He carried his rifle at his hip, and he limped and cursed angrily.

"Come across," shouted Durkin. "Give me the key to that stone house.

Snap into it, and no argument."

"The key--to the stone bank?" repeated old Gurlone.

"Yes. I'll give you five counts to throw it over--then I'll shoot you and take it," snarled Durkin savagely. "I want that treasure, whatever it is, and I'll have it. One ... two ... three...." The tramp sent a shot over their heads as a warning.

"Hey, Bill, easy, easy," pleaded Maget. "That stuff is radium. It'll ruin you, boy!"

"Shut up, you yeller-bellied b.u.m," snarled Durkin. "Four...."

A tinkle of metal came on the stone floor of the laboratory, as old Gurlone tossed his keys to Durkin.

"Don't go in that shack," cried young Gurlone. "It'll be your death, man--"

"Liars," yelled Durkin, and backed out the door.

"H'm," said old Gurlone, turning to Maget. "So you came to rob us, eh?"

But Maget thought of Juan, and then he knew he did not want Durkin, in spite of his failings, to perish so. He ran for the door, and across the clearing.

"Durkin--Bill--wait, it's Frank--"

Great bellowings sounded from the bowels of the earth, but Maget ignored these in his effort to save his partner. Durkin had the padlock off the stone shack, and pulled back the door.

As the door disclosed the interior, Maget could see that a greenish haze filled the entire building. Wan liquid light streamed forth like heavy fluid.

Bravely, to save his pal from death, Maget ran forward. But Durkin had entered the stone shack.

Maget went to the very door of the building. Durkin was inside, and Maget could see his partner's thick form as a black object in the strange, thick air.