The others nodded agreement and sat watching. In the shadows no creature moved. Afar off some bird cried mournfully like a lost soul condemned to wander forever alone in the grim green solitudes. No other sound came to the listeners save the ever-present hum of the big forest mosquitoes, to which they now had become indifferent. For all they could see or hear of their two guides, they might as well have been alone. Yet they knew the Brazilians were not far away, threading the maze with sure step and scouting hawk-eyed for any sign of danger.

At length a long soft whistle sounded in the bush ahead. Any Indian hunter hearing that sound would straightway have begun scanning the high branches, for the liquid call was that of the mutum, or cura.s.sow turkey.

But the waiting trio knew it for Pedro's signal that all was clear. At once they slid their canoe to sh.o.r.e, lifted its bow to a firm grip on the clay, and, after plumbing the shadows, quietly advanced in squad column.

A few steps, and they halted suddenly and whirled. A voice had spoken just behind them. There, squatting leisurely between the root b.u.t.tresses of a huge tree, Lourenco looked up at them in amus.e.m.e.nt. They had pa.s.sed within rifle length of him without seeing him.

"Of what use are your eyes, comrades?" he chaffed. "In the bush one should see in all directions at once. You were looking at that patch of sunlight just ahead, yes? But danger lurks in the shadows, not in the glaring light."

Without awaiting an answer, he arose and took the lead. At the edge of the small sunlit s.p.a.ce beyond he halted.

"You were heading for the right place," he added then. "Look around. Do you see anything?"

Swiftly they scrutinized the gap left by the fall of a great tree whose gigantic trunk had bludgeoned weaker trees away in its crushing descent.

Seeing nothing unusual, they then peered around them. Tim suddenly snapped up his rifle.

"Holler tree there--and a man in it! Hey! come out o' there!"

"Your eyes improve," Lourenco complimented. "But the man is Pedro."

Tim lowered the gun as Pedro, grinning, came out of his concealment.

"That is the tree of the Raposa," Lourenco went on. "The lightning flashing in from above showed us the man. But now, senh.o.r.es, I think we must tramp the bush for some time before we find that Raposa again.

There is no trace of him here."

"Hm!" said Knowlton. Striding to the hollow tree, he peered about inside it. The cavity was almost big enough to sling a hammock in, but it was empty of any indication of habitation, human or otherwise. A temporary refuge--that was all.

"No sign anywhere around here, eh?" queried McKay.

"We have found none. We shall look farther, but I have small hope. If you senh.o.r.es will make the camp this time we shall start at once and stay out until dark. Build no fire until we return. And if you hear the call of the mutum, pay no attention to it; we may use it to locate each other if we separate, and also perhaps as a decoy. Any wild man, red or white, hearing that call would seek the bird making it, for a fine fat mutum is well worth killing. Keep quiet and be on guard."

"Right. Go ahead."

The bushmen turned at once and stole away. The others returned to the canoes, transported the necessary duffle to the base of the hollow tree, made camp with a few poles, and squatted against the trunk to smoke, watch, and wait. Several times they heard mutum calls receding in the distance. Then came silence.

The sun-thrown shadows in the gap crawled steadily eastward. Knowlton tested the feed of his automatic, which, since its balkiness in the fight with the Peruvians, he had kept carefully oiled and free from the slightest speck of rust. Tim arose at intervals and paced up and down in sentry go, eyes and ears alert--a useless activity, but one which provided an outlet for his restless energy. McKay let his gaze rove over the small area visible from their post, studying the contours of the towering trunks, the p.r.o.ne giant whose fall had opened the hole in the leafy roof, the parasitical vines twined about other trees, the thin, outflung b.u.t.tresses supporting the mighty columns--all familiar sights to him, but the only things to occupy his vision. So limned on his brain did the scene become that after a time he could close his eyes and see it in every important detail.

It might have been two hours after Pedro and Lourenco had departed--the shadows had grown much longer--when over McKay stole the feeling that he was being watched. He glanced at his companions and found that neither of them was looking at him. Knowlton, sitting with hands clasped around updrawn knees, was dozing. Tim, though wide awake, was staring absently at a fungus. The captain's eyes searched the short vistas all about, spying nothing new. Still the feeling persisted. Then all at once his roaming gaze stopped, became fixed on a point some forty feet away.

There rose a rough-barked red-brown tree, and from it, near the ground, projected a blackish bole. McKay was very sure the protuberance had not been there before. He had stared steadily at that tree more than once, and its shape was quite clear in his mind. Was that b.u.mp an insensate wood growth now revealed for the first time by the changing sun slant, or--

For minutes he watched it. It did not move. Then Tim, restless again, rose directly in McKay's line of sight, yawned silently, swung his gun to his shoulder, and began another slow parade of his self-appointed post. When he had stepped aside McKay looked again for the puzzling bole.

It was gone.

With a bound the captain was up and dashing toward the tree, drawing his pistol as he ran. But within three strides he went down. A tough vine, unnoticed on the ground, looped snakily around one ankle and threw him hard. His gun flew from his hand. As he fell a tiny whispering sound flitted past, followed by a small blow somewhere behind him. Ensued a gruff grunt from Tim and the swift clatter of a breech bolt.

Raging, McKay kicked his foot loose and heaved himself up. Empty handed, he continued his rush for the tree. But when he reached it he found nothing behind it. If anything had been there it now was gone, and the vacant shadows beyond were as inscrutable as ever.

Feet padded behind him and Tim and Knowlton halted on either side. A moment of silent searching, and Tim broke into reproach.

"Cap, don't never do that again! If ye take a tumble in my line o' fire, for the love o' Mike stay down till I shoot! I come so near drillin' ye when ye hopped up that I'm sweatin' blood right now."

In truth, the veteran was pale around the mouth and his broad face was beaded with cold drops.

"I seen more 'n one time in France when I felt like shootin' my s'perior officer, but I never come so near doin' it as jest now. I had finger to trigger and had took up the slack, and a hair's weight more pull would have spattered yer head all around. And besides givin' me heart failure ye let that guy git away. We'll never find him--"

"You saw him?" McKay cut in.

"I seen somethin' beyond ye--couldn't make out what 'twas, but from the way ye was goin' over the top I knowed it must be a man. And then when the arrer come--"

"Arrow?"

"Sure. Missed ye when ye took that flop, and stuck in the tree over yonder. What'd ye rush the guy for, anyways? Whyn't ye drill him from where ye was?"

In the reaction from his sudden fright Tim was as wrathfully ready to "bawl out" his captain as if he were some raw rookie. McKay, with a cool smile, explained his abrupt action, meanwhile reconnoitering the dimness for any further sign of the vanished a.s.sailant. None showed.

While Tim stood vigilant guard the other two stooped and moved around the base of the tree, narrowly examining the ground. Beyond it they paused at one spot, fingered the soil lightly, and lit a match or two.

"No ghost," said Knowlton. "Barefoot man. Didn't leave much trace, but enough to show he was here. Let's look at that arrow."

Back to the hollow tree they went, retrieving McKay's pistol on the way.

About a yard above the earth a long shaft projected from the bark.

Knowlton reached for it, but McKay held him back and drew it out.

"M-hm! Thought so!" he muttered. "Poisoned."

"Oof! Nice, gentle sort of a cuss," rumbled Tim. "That smear on the point--is that poison?"

"Poison. Quickest and deadliest kind of poison. Mixes instantly with blood. Paralysis--convulsions--death. The least scratch and you're gone.

Wicked head on this thing, too: looks like a piece of serrated bone. See all those little barbs along the edges? War arrow, all right."

"Meanin' that we'll be jumped pretty soon by more Injuns. If that guy's on the warpath he ain't alone."

"Wouldn't be a bad idea to take cover," nodded McKay. Turning the five-foot shaft downward, he plunged its head into the soft ground and left it sticking there, harmless.

"Tim, go down and guard the canoes. Merry, lie in between these roots and keep watch off that way. I'll go over to that tree where the spy hid."

For another hour the camp was silent. Each in his covert, finger on trigger, the trio watched with ceaseless vigilance, expecting each instant to detect dusky forms crawling up from tree to tree. Yet nothing of the sort came. Nor did any hostile sound reach them. Somewhere parrots squawked, somewhere else the puppylike yapping of toucans disturbed the solitude; nothing else.

The wan light faded. The sun crawled up the trees, leaving all the ground in shadow. Then, not far off, sounded the soft whistle of the mutum. Suspicious, the watchers held their places until, with another whistle, Pedro came into view, followed by Lourenco.

McKay arose, met them, and briefly explained the situation. They nodded, but seemed undisturbed.

"We can start a fire now, Capitao," Lourenco said. "Night comes and we are hungry. There will be no danger before another dawn."

With which he leaned his rifle against a tree and started immediate preparations for a meal. Pedro continued on to the canoes, made sure they were drawn up high enough to remain in place in case of any sudden rain, and returned with Tim. Around them now resounded the swiftly rising roar of the nightly outbreak of animal life. The sun vanished. At once blackness whelmed all except the little fire.

"See anything while you were out?" asked McKay.