The explorer smiled. “If you’d ever seen one of these Indians stalk game you would not ask the first question,” he replied. “Do you notice that they always use small bore, muzzle-loading guns and double ‘B’ shot and yet they kill tapir and jaguar? They could only do that by getting so close to their quarry that the light charge of shot acts like a solid ball. In other words, they creep within a dozen feet of the most wary creatures in the South American jungle and an Indian who can do that could sneak into those fellows’ camp and be within arm’s reach without being seen or heard. As for being captured, why there’s no more chance than of capturing a ghost! And if by a miracle they were seen why should those rascals ever suspect the Bucks knew anything about them or us, or had any connection with officers whom they probably imagine are hundreds of miles distant? No, don’t worry on that score.”

At this moment a low, plaintive, long-drawn whistle was borne faintly from the forest across the stream and instantly the Indians leaped up and stood motionless, listening intently and peering apprehensively across the river.

Once more, from the black depths of the jungle, came the mysterious sound and hastily gathering up their half-finished meal, the Indians came crowding close to the group of white men.

“Eh, eh, Joseph! Why makeum for ’fraid like so?” queried Mr. Thorne. “What you sabby?”

Joseph turned fear-wide eyes and terrified features towards the explorer. “Kenaima!” he exclaimed in a whisper.

Mr. Thorne whistled. “So that’s it!” he ejaculated. Then, turning to the Indians, “No makeum ’fraid, Joseph! Kenaima no makeum walk this side. No huntum you fellow Buckman same way!”

“Please tell us, what does he mean?” begged Tom, utterly at a loss to understand what had frightened the Indians or what the explorer was talking about. “What is a Kenaima?”

“The blood avenger,” replied Mr. Thorne in a low voice. “If an Indian is killed, tribal law demands that his slayer must be destroyed, and not only the assassin must pay the penalty but all his relatives as well. The man chosen to wreak vengeance is the ‘Kenaima’ or, as the Indians believe, a man in whom the spirit of vengeance takes up its abode until its mission is accomplished. Until the Kenaima kills his victim he cannot see or speak to any living being, but must live alone, ever trailing the one he seeks until he has wreaked vengeance. He may chose either one of two forms--the ‘tiger Kenaima’ or the snake or ‘camudi Kenaima.’ If the former, he must strike down his man with a short club, if the latter he must strangle him, but in either case he must not kill his victim outright at once. Instead he must disable him and then return three days later when the wounded man is put out of his misery by the Kenaima driving a wooden spear through his body. Then the avenger must lick the blood from the spear or--so they believe--the spirit of vengeance will not leave and the Kenaima will go mad, ranging the forests and killing all he meets.”

“Uugh! it makes me shiver,” cried Tom, edging closer to his father and the fire.

“And I thought these Indians were peaceable!” exclaimed Frank as he glanced nervously about.