BOB had often run in track races at high school, but never had he equaled the pace that was now taking him to the boats. It was as though wings had suddenly lifted him through space at an alarming rate of speed.

The youth had all he could do to prevent coming in contact with thorns and fringed plants, but he did his best. But what of thorns when Professor Bigelow needed help?

On and on he went, swinging his rifle over shrubs and bushes. At times it was necessary to hold his arms high above his head to prevent striking limbs and other projections.

At last, after what seemed a terribly long time, he parted the foliage and gazed ahead to see what was happening. Then a look of rage came on his face.

On the river bank a terrific struggle was taking place between Professor Bigelow and the two Indians who had been left behind. The men had the professor down, and the latter’s face was ghastly white as strong arms and hands tried to choke him into unconsciousness. Occasionally he would manage to call out a muffled cry for assistance.

For a moment Bob took in the situation carefully. Then he rushed at the men with rage and fury and landed on the back of the one nearest, bearing him to the ground with a thud. The Indians glanced up in surprise at this abrupt interruption, and they turned to deal with this new enemy.

One of the men gained his feet and launched himself with all force at Bob’s side, the impact hurling the youth from the back of the first man. But Bob shook the fellow off and threw an arm around his neck with the strength of one in desperation. There was a terrific struggle, and the two thrashed about, neither able to gain the upper hand. Bob gripped the Indian’s neck with all his strength, and the man’s face began to turn purple from the terrific strain. It was clearly evident that he would soon be put out of the fight.

But the other Indian was not motionless. In fact if it had not been for him, the youth would have had the better of the first fellow, for he was slowly giving out. But suddenly Bob felt a heavy body landing on his back and had to release his hold on the first man.

This again gave the Indians the advantage, and they were quick to sense their chance.

Bob soon saw that he could gain nothing as things were. He must resort to some other means.

Professor Bigelow was now beginning to show signs of life, but he was so badly battered that what little he did to help amounted to nothing, for he was soon sent sprawling to the ground.

Suddenly Bob gained his feet, intent upon resorting to boxing, a method that the Indians probably knew little about.

A quick glance around showed that his friends had arrived and were making for the boats as fast as they could. But it was only a glance, for the Indians were rushing at him with redoubled force.

Bob caught the first man squarely between the eyes and sent him sprawling to the ground in a dazed condition. The other Indian saw that it would be useless to continue the fight, for the other whites were returning fast.

He turned and made for the boat, Bob at his heels. The youth suspected that the man was going after a gun, and he was right. But he hardly had the revolver in his hand when Bob pounced upon him and wrenched the weapon from his grip. One hard blow put him out of the fight.

Then, for the first time, Bob drew a long breath. He was panting and gasping from exertion, but he hurried over to Professor Bigelow.

“Are you all right?” he asked.

“Yes,” the professor replied, getting to his feet. And then: “That was a wonderful fight you put up, Bob. If you had come much later, the Indians would have escaped with the boat and our provisions.”

“So that was their game!” said Mr. Lewis angrily, glancing at the still limp Indian on shore. “They wanted to put you out and then escape with the boats, leaving us here to starve!”

He drew his fist, and for a moment it looked as if another fight were going to take place.

“Just for that we should desert them,” gritted Joe.

“Can hardly do that,” said Mr. Holton. “It would amount to the same as murder for robbery, and such punishment is unjust. Now if they had killed one of our party it might be different. Even then I’d hesitate to do it.”

“But they’ve got to have some kind of punishment,” persisted Joe. “Who knows but that they’ll attempt the same thing later?”

“We’ll have to keep a close lookout,” returned the professor. “If we see any more treachery we won’t dare take any more chances.”

The other members of the crew could not understand the actions of the two would-be deserters, and at once cast them aside as traitors, calling them names which, had they been translated into English, would have been extremely shocking to civilized persons.

In a short time the two Indians emerged into consciousness, and they sat awaiting any fate that might be thrust upon them. The explorers were at a loss to know what to do with the men, but they finally decided to give them hard jobs in full view of all, so that they could neither escape again with the boats nor get the others of the crew to thinking their way.

“Probably won’t have any more trouble,” remarked Mr. Lewis, as they prepared to start up the river again. “We’ll keep a sharp lookout, and if we see any more dishonesty we’ll act accordingly.”

The specimens were prepared, and they resumed the journey up the river, hoping that few more days would pass before they found the unknown Indians. The whites were anxious and yet rather fearful to come in contact with them, fortified as the boats were. Professor Bigelow, however, took the matter lightly, and often when his friends thought of his numerous visits to strange tribes, many of them hostile, they were inclined to cast aside their worries and leave the future happenings to him. For surely, with his wide experience, he could see to any predicament.

“We want to make good time today,” said Mr. Holton. “Twenty-five miles, at least.”

“We will,” Joe’s father assured him. “Unless,” he added, “more rapids hold us back.”

“I don’t think—I hardly believe they will,” Professor Bigelow said, but this was a statement of hope rather than of conviction.

Bob and Joe constantly took motion pictures of the country they were passing through, and often they took the cameras with them on hunting trips, to photograph not only wild life but any adventures that they might have. The number of feet of exposed film had grown to nearly a thousand, and they intended to make it several more before they “closed” the picture. They were allowed four thousand feet and fully expected to use all of it.

The next day after the fracas with the traitorous Indians, they were paddling swiftly along when suddenly there was a jar and a crash, and the foremost boat was sent aside and heading in the opposite direction. At once the explorers were on their feet and had their rifles in ready grasp. They cautiously peered over the side into the river, half expecting to see a dozen or more savages leap out and make for the boat.

But no savages came. Instead there arose a large black body, nearly ten feet long, shaped like a seal, with the faintest suggestion of fins protruding from its side. For a moment it glanced about, then swam on up the river.

“A manatee,” said Mr. Holton. “Or sea-cow, if you prefer that name.”

“Sure is a whopper,” observed Joe. “Looks like it might be dangerous. Is it?”

“No,” his father replied. “One of the most harmless animals of South America.”

Mr. Lewis raised his rifle to bring the creature down as a specimen, but just as he prepared to pull the trigger it darted below the water and swam off at a rapid pace, leaving a thin streak of ripples behind. Then the naturalists saw that shooting would mean only a waste of bullets.

A few miles on they came upon another rapids and saw that it would be necessary to lay a portage of logs along the river bank in order to get the boats through. Anxious to make time, they worked untiringly and had the task completed in a short time.

“Now to get the boats through,” said Mr. Holton, beginning to unload their contents.

The canoes were heavy, even with the provisions removed, and it required all the combined strength of the whites and the Indian crew to get them beyond the rough stretch. But the undertaking was finally finished.

Next the provisions were carried around, placed in the boats, and the latter were moved into the river. At last the strenuous task was completed.

“Ready to go again?” asked Joe.

“It’s about noon,” said Professor Bigelow. “I suggest that we get a lunch.”

The others agreed, and an ample repast was prepared.

Then Mr. Lewis advised that they take it easy under low palm trees. The others, with the exception of Bob and Joe, were glad of a chance to repose. The boys, however, were restless and eager to explore the surrounding territory. Unlike their elders, their tireless limbs cried out for action, even after hard labor.

“We’ll be careful and not take any chances,” Joe assured the men.

But had they realized what dangerous country they were in, they would never have started out.