The place, located on the smooth rock floor of a large natural basin, seemed a veritable cauldron of seething colors which rippled and blended in a dazzling maze of unearthly splendor. But Dixon forgot everything else in that weird camp as his startled gaze fell upon the creature standing directly in front of him.

He knew instinctively that the thing must be one of the Alpha Centaurians, for in its alien grotesqueness the figure was utterly dissimilar to anything ever seen upon Earth before.

Life upon the shattered planet of that far distant sun had apparently sprung from sources both crustacean and reptilian. The Centaurian stood barely five feet in height. Its bulky, box-like body was completely covered with a chitinous armor that gleamed pale yellowish green.

Two short powerful legs, scaled like those of a lizard, ended in feet that resembled degenerated talons. Two pairs of slender arms emanated from the creature's shoulders, with their many-jointed flexible length ending in delicate three-p.r.o.nged hands.

The scaly hairless head beneath the Centaurian's white globe device bore a face that was blankly hideous. Two great lidless eyes, devoid of both pupils and whites, stared unblinkingly at Dixon like twin blobs of red-black jelly. A toothless loose-lipped mouth slavered beneath.

Dixon averted his gaze from the horror of that fearful alien face, and looked anxiously around for Ruth. He saw her almost at once, over at his right. She was tethered by a light metallic rope that ran from her waist to one of the metal beams supporting the great shimmering ball of opalescent fire which formed the central control of the hybrids.

One of the white globe devices had been placed upon Ruth's head and she was apparently unhurt, for she pluckily flashed a rea.s.suring smile at Dixon.

Directly in front of Dixon and some forty yards away there was a large pen-like enclosure, with vari-colored shafts of radiance from banks of projectors constantly sweeping through it. Dixon drew in his breath sharply as he saw the frightful life lying dormant in that pen. It was a solid ma.s.s of hybrids--great loathesome figures fashioned from a score of different worms, insects, and spiders. The globes upon the gruesome mammalian half-heads were still dark and unfired with opalescence.

The invaders had apparently raided most of the surrounding country in obtaining those grafted half-heads. Near where Dixon stood there was a tragic little pile of articles taken from the Centaurians'

victims--prospectors' picks, shovels, axes, and other tools.

Over to the left of the dormant hybrids stood the second Alpha Centaurian, curiously examining Dixon's projectile. The creature apparently suspected the deadly nature of the gleaming cylinder for it soon laid it carefully down and packed cushions of soft fabric around it to shield it from any possible shock.

Then at an unspoken command from the first Centaurian the great hybrid whirled Dixon around to face a small enclosure just behind him in which were located banks of control panels and other apparatus. One of the pieces of mechanism, with a regularly s.p.a.ced stream of sparks snapping between two terminals, was apparently a radio receiver automatically recording the broadcast from the s.p.a.ce ship. Dixon was unable to even guess the nature of the remaining apparatus.

"Bruce, be careful!" Ruth called in despairing warning. "He is going to put the thought-reading machine on your brain. Then he'll learn what the projectile is for, and everything will be lost!"

Dixon's mind raced with lightning speed in the face of this new danger. He stealthily slipped a hand over the revolver in his pocket.

There was one vulnerable spot in the great hybrid holding him, and that was the opalescent globe on the creature's head. If he could only smash that globe with one well-directed shot, he might be able to elude the Centaurians for the precious minute necessary to send the projectile on its deadly journey.

The hybrid began maneuvering Dixon toward the instrument enclosure.

For a fleeting second the grip of the tentacles upon his shoulders loosened slightly. Dixon took instant advantage of it. Twisting himself free from the loosened tentacle in one mighty effort, he whirled and fired pointblank at the opalescent globe on the head looming above him.

The bullet smashed accurately home, shattering the globe like a bursting bubble. The great hybrid collapsed with startling suddenness, its life force instantly extinguished as the globe burst.

Dixon leaped to one side and swung the gun into line with the Centaurian's hideous face. He pulled the trigger--but there was no response. The rusty old firearm had hopelessly jammed.

Dixon savagely flung the revolver at the Centaurian. The creature tried to dodge, but the heavy gun struck its body a glancing blow.

There was a slight spurt of body fluid as the chitinous armor was partly broken.

Dixon's heart leaped exultantly. No wonder these creatures had to create hybrids to fight for them. Their own bodies were as vulnerable as that of a soft-sh.e.l.led crab!

The Centaurian quickly drew a slender tube of dark green from a scabbard in its belt. Dixon dodged back, looking wildly about him for a weapon. There was an ax in the pile only a few yards away. Dixon s.n.a.t.c.hed the ax up, and whirled to give battle.

The other Centaurian had come hurrying over now to aid its mate. Dixon was effectually barred from attempting any progress toward the projectile by the two grotesque creatures as they stood alertly there beside each other with their green tubes menacing him. Dixon waited tensely at bay, remembering those searing radium burns upon Emil Crawford's body.

Then the first Centaurian abruptly leveled a second and smaller tube upon Dixon. A burst of yellow light flashed toward him, enveloping him in a cloud of pale radiance before he could dodge.

There was a faint plop as the protecting white globe upon his head was shattered. The yellow radiance swiftly faded, leaving Dixon unhurt, but he realized that the first round in the battle had been won decisively by the Centaurians. His only chance now, was to end the battle before the paralyzing rays of the green moon sapped his strength.

He warily advanced upon the Centaurians. Their green tubes swung into line and twin bolts of violet flame flashed toward him. He dodged, and the bolts missed by inches. Then Dixon nearly fell as his foot struck a bundle of cloth on the ground.

The next moment he s.n.a.t.c.hed the bundle up with a cry of triumph. It was his lead-cloth tunic, torn and useless as a garment, but invaluable as a shield against the searing effects of those bolts of radioactive flame. He hurriedly wrapped the fabric in a rough bundle around his left forearm. The next time the tubes' violet flames flashed toward him he thrust his rude shield squarely into their path.

There was a light tingling shock, and that was all. The bolts did not sear through.

With new confidence, Dixon boldly charged the two Centaurians. A weird battle ensued in the garishly lighted arena.

The effective range of the violet flashes was only about ten feet, and Dixon's muscular agility was far superior to that of his antagonists.

By constant whirling and dodging he was able to either catch the violet bolts upon his shielded arm or else dodge them entirely.

Yet, in spite of the Centaurians' clumsy slowness, they maneuvered with a cool strategy that constantly kept the Earth man's superior strength at bay. Always as Dixon tried to close with one of them he was forced to retreat when a flanking attack from the other threatened his unprotected back. And always the Centaurians maneuvered to bar Dixon from attempting any dash toward the projectile.

The minutes pa.s.sed, and Dixon felt his strength rapidly ebbing, both from his herculean exertions and from the paralyzing rays of the green moon beating down upon his unprotected head. As his speed of foot lessened the Centaurians began inexorably pressing their advantage.

Dixon was no longer escaping unscathed. In spite of his frantic efforts to dodge, twice the violet bolts grazed his body in searing flashes of exquisite agony.

His muscles stiffened still more in the attack of the Green Sickness.

Desperately dodging a Centaurian bolt, he stumbled and nearly fell. As he staggered to regain his balance, one of his antagonists scrambled to the coveted position behind him.

It was only Ruth's scream of warning that galvanized Dixon's numbed brain into action in time to meet the imminent peril.

In one mighty effort he flung his ax at the Centaurian in front of him. The heavy blade cut deep into the thinly armored body. Mortally wounded, the creature collapsed.

Dixon whirled and flung up his shielded left arm just in time to intercept the violet bolt of the other Centaurian. Warily backing away, Dixon succeeded in retrieving his ax from beside the twitching body of the fallen invader.

Then, with the heavy weapon again in his hand, he remorselessly charged his remaining foe. The Centaurian's tube flashed in a veritable hail of hurtling violet bolts, but Dixon caught the flashes upon his shield and closed grimly in.

One final leap brought him to close quarters. The heavy ax whistled through the air in a single mighty stroke that cleft the Centaurian's frail body nearly in two.

Then Ruth's excited scream came again. "Bruce--the other one! Get it quick!"

Dixon turned. The wounded invader, taking advantage of their preoccupation in the final struggle with its mate, had dragged its crippled body over to the instrument enclosure. Dixon staggered toward it as fast as his half-paralyzed muscles would permit.

He was just too late. The Centaurian jerked a lever home a fraction of a second before Dixon's smashing ax forever ended his activities. The lever's action upon the pen of inert hybrids was immediate.

The sweeping lances of light vanished in a brief sheet of vivid flame which kindled the dark globes on the hybrids' gruesome heads to steady opalescence--and the dread horde came to life! Sprawling from the pen, they came scuttling toward Dixon in a surging flood--a scene out of a nightmare.

Dixon faced the oncoming horde in numb despair, knowing that his nearly-paralyzed body had no chance in flight. Then, just as the hybrids were nearly upon him, he heard Ruth's encouraging voice again.

"There's still one chance left, Bruce," she cried, "and I'll take it!"

Dixon turned. Ruth had in her hand the tiny contact grenade he had given her for a last emergency. She snapped the safety catch on the little bomb, then hurled it squarely at the giant opalescent globe looming close beside her.