Now took place an unprecedented incident.

The air of comity, or at least neutrality, which brooded over the two parties had given way to that of silent but intense hostility. The prowling movement of the native with the spear as he slipped into the wood, the sudden advance of Jared Long, whose face became like a thunder-cloud, when every hope of a friendly termination vanished, and the abrupt halt of the bowman, showed that all parties had thrown off the cloak of good will and become deadly enemies.

The third savage kept his place farther down the stream, his black eyes fixed on the archer in front, while he doubtless was waiting for some action on the part of his comrade who had stolen into the wood. As has been stated, he was nigh enough to hurl his javelin, so that both the white men were too wise to eliminate him from the curiously involved problem that confronted them.

The bowman having halted, stood a moment with his piercing black eyes fixed on the nearest white man, as if seeking to read in his face the meaning of his action or rather abrupt cessation of action.

"Professor," called Jared, "I'll attend to the one in front of you; but look out for the scamp among the trees."

Grimcke was relieved to hear this, and had there been only the two natives to confront, he would have been disturbed by no misgiving, but there were signs that the third one down the stream was preparing to do his part in the treacherous business. He too began advancing, but instead of doing so with the quick, angry stride of the New Englander, he stepped slowly and softly, as if seeking to conceal his movement.

Grimcke would have been glad to turn the archer over to the care of Long, but he was so frightfully close, that he did not dare do so. A moment's delay on the part of his friend would be fatal. At the same time, it was not to be forgotten that the most stealthy foe of all was prowling among the trees on the right.

The Professor's hope, as has been explained, was that his own retrogression had disconcerted the plans of this special miscreant for whom, however, he kept a keen watch.

The archer still held his bow, with the arrow in place grasped by his right hand, the long weapon resting against his hip. Provided he was right-handed, the bow would have to be shifted to his left hand, the arrow drawn back with the right and the missile then launched at his foe. This, it would seem, involved enough action to give both Grimcke and Long abundance of time in which to anticipate him.

But there remained the possibility that the savage was left-handed, in which event, the necessary action on his part would be much less, though sufficiently complicated to afford the white men abundance of time to anticipate him.

The native was left-handed, with a quickness that surpassed all expectation, the bow was suddenly raised, the end of the arrow drawn back and the missile driven directly at the breast of Grimcke.

At precisely the same instant, the latter's strained ear caught the crackling of a twig, above the din of the rapids (which was much less there than below), and something was discerned moving among the trees on his right. His frightened glance in that direction gave him a glimpse of a dusky figure in the act of hurling his javelin.

Thus it was that the spearman and archer let fly at precisely the same instant, and Jared Long, who was so anxious to help his friend, saw only the deft movements of the archer. Grimcke could not fire at both in time to save himself, but he instinctively did the very best and indeed the only thing that could be done. Without moving his feet, he dropped to a sitting posture, instantly popping up again like a jack-in-the-box.

The movement took place at precisely the right instant, and both the javelin and arrow whizzed over his head, without grazing him, but the arrow shot by Long's temple so close that he blinked and for an instant believed he had been hit.

But, like the hunter when bitten by a rattlesnake, he determined to crush his assailant and to attend to his hurt afterwards.

The sharp crack of the Winchester, the shriek of the smitten savage and his frenzied leap in the air, followed in such instant succession that they seemed simultaneous. When the wretch went back on the ground he was as dead as Julius Caesar.

A man can fire with amazing rapidity, when using a Winchester repeater, but some persons are like cats in their own movements. The New Englander leveled his weapon as quickly as he could bring it to his shoulder, but the native along the side of the Xingu had vanished as though he never existed.

Whether he knew anything about fire-arms or not, he was quick to understand that some kind of weapon in the hands of the white men had knocked the bowman out of time, and he bounded among the trees at his side, as though he, too, was discharged from the bow. He was just quick enough to escape the bullet that would have been after him an instant later.

The moment Grimcke knew that he was safe from the javelin, which sped over his head, he straightened up, and, still maintaining his removable posture, discharged his gun at the point whence came the well-nigh fatal missile.

But the shot was a blind one, for he did not see the native at the instant of firing. Nothing could have surpassed the alertness of these strange savages. The one with the javelin disappeared with the same suddenness as did his brother down the bank, and, had the archer but comprehended his danger he, too, would have escaped.

The affray roused the wrath of both Long and Grimcke. They had offered the hand of friendship, only to be answered with an attempt upon their lives. One of their assailants had eluded them, and the other would have been an assailant had the opportunity been given.

"Let's shoot him too!"

He alluded to the man who hurled the javelin and who, so far as they could see, was left without any weapon with which to defend himself. In their natural excitement over their victory, the friends forgot themselves for the moment. Heedless of consequences, they dashed among the trees, in pursuit of the savage who had flung his spear with well-nigh fatal effect.

The undergrowth was frightfully tangled, and, as the first plunge, the Professor went forward on his hands and knees. The wonder was how Long kept his feet; but it will be remembered that he was much more attenuated than his companion, and seemed to have picked up a skill elsewhere which now stood him well.

The moon was shining and despite the dense vegetation around him, enough rays found their way to the ground to give him a partial view for few paces in front. He had not gone far when he caught a glimpse of the dusky figure slipping through the undergrowth ahead, and at no great distance.

Strange as it may seem, the impetuosity of the American caused him to gain upon the terrified native, who, having flung his poisoned weapon, was without the means of defending himself. It was not in the nature of things, however, that Long should overtake the fugitive, who was more accustomed to making his way through such obstructions. The first burst of pursuit caused the white man to believe he would win in the strange race, but the next minute he saw he was losing ground.

Determined that the wretch should not escape, he checked his pursuit for an instant, and, bringing his Winchester to his shoulder, let fly.

But brief as was his halt, it give the savage time to make one terrific bound which shut him almost from sight, and rendered the hasty aim of Long so faulty that his intended victim was not so much as scratched.

Had the savage dashed deeper into the forest, he would have passed beyond all peril at this moment, but he was seeking to do that which Long did not discover until after discharging his gun. He headed toward the river, where he was first seen. It must have been that he was actuated by a desire to go to the help of his comrade, or more likely he was anxious to recover his javelin, in which he placed unbounded faith, and believed he could do it without undue risk.

Whatever his purpose, he quickly burst from the forest, while Long, who was pushing furiously after him, discovered from the increasing light in front, that he was close to the Xingu again.

Suspecting his purpose, the white man tore forward at the most reckless speed, and, before the native could recover his weapon and dart back to cover, he himself had dashed into the moonlight.

"Now, we've got him!" he shouted; "there's no getting away this time!"

This exultant exclamation was uttered to a form which appeared on his right, and who he was certain was the Professor; but to his consternation, as he turned his head, he saw that it was the other native, javelin in hand!