But, as the noise grew louder, they hesitated no longer, but pressed right on. Suddenly, on emerging into an open space where the growth had been flattened out in every direction, they came on a scene that, for an instant, almost deprived them of their breath.

In the midst of the open space, Nat and Joe were bending over the form of Ding-dong, who was stretched on the ground, seemingly unconscious. Not far off, an immense snake, which must have been fully fifteen feet long, was lashing wildly about in its death agonies.

“Oh, professor!” cried Nat, as he saw the newcomers, “we’re so glad you have come. Ding-dong was attacked by that serpent and badly crushed. It was only by firing at the creature that we managed to save his life.”

“Is he badly hurt?” choked out Joe anxiously.

The professor, who had been bending over the unconscious lad, shook his head.

“Merely shock, and possibly a sudden weakening of the heart,” he said. Taking a small vial from a pocket medicine-case, the professor forced some of its contents between Ding-dong’s lips. In a few moments the boy was able to sit up and take notice of things about him.

By this time the convulsive dying movements of the snake had ceased, and it lay still.

“Ugh! What a monster!” shuddered Ding-dong. “I can feel his terrible folds around me yet.”

As usual, when under the stress of emotion, Ding-dong’s hesitating manner of speech had left him, and he enunciated quite plainly.

“How did it happen?” asked the professor.

“I was looking for wood,” explained Ding-dong, “and thought I had found a f-f-f-fi-fine c-c-chunk of timber. But w-w-when I pu-pu-put my hand on it, the ber-ber-blessed thing turned out to be a snake. I yelled at the top of my voice, and started to run, but before I had gone far I tripped and fell. The n-n-n-n-next instant the snake had me.”

“Joe and I were a short distance off,” chimed in Nat, taking up the story, “and heard Ding-dong’s yell. We hurried to him, and you can imagine how horrified we were to see him struggling with that serpent. Joe raised his rifle, but then lowered it again. He was scared to shoot at the snake for fear of hitting Ding-dong. But at last we saw a chance. I fired once and Joe twice.”

“And all three bullets penetrated the brute in and about the head,” struck in Mr. Tubbs, who had been examining the snake.

“So they did,” declared the professor, as he and the boys joined the ruddy-headed one; “good shooting, boys. This snake is of the boa variety. They are common all along this coast, but usually they are thickest near rivers. As a rule, they will not attack human beings, although cases have been recorded of their doing so. I imagine that it was Master Bell’s having grabbed him that angered his snakeship. Shall we take the skin for a souvenir?”

“N-n-n-no, thank you,” stuttered Ding-dong, “it will be no trouble to re-re-remember that f-f-f-fellow without having to l-l-l-look at his skin.”

“I agree with you,” said Mr. Tubbs. “I guess we’ll leave him here for a while. It won’t be long before some animal or other makes away with it.”

Leaving the repulsive looking carcass on the ground, they set out to return to the Discoverer.

“Well, all is well that ends well,” said the professor, as they tramped along; “at first I had a dreadful fear that you lads had been attacked by Indians.”

“Indians!” exclaimed Nat. “Are there Indians in this part of Bolivia?”

“Oh, yes; several tribes,” was the rejoinder.

“Are they savage?” inquired Joe.

“I am sorry to say that they are. In other parts some of the natives have been converted to Christianity, but the natives of this section are fierce and warlike. I hope we shall manage to steer clear of them.”

“What is the tribe called?” asked Nat.

“They are known as the Caripunas,” was the rejoinder. “The early Jesuits had much trouble with them, and they have ever since remained in a more or less wild and hostile state. They are very much averse to having any one enter their country, and that was one of the minor reasons why this trip was made by means of the dirigible.”

“Their country!” echoed Joe. “I should think the Bolivian government would send a regiment up here and subdue the rascals.”

“Several such expeditions have been despatched,” was the response, “but the fate of all has been the same. Several months after their departure the remainder of the force has come straggling home, more dead than alive, to tell a tale of death and defeat.”

“But how can Indians cope with civilized troops?” Nat wanted to know.

“For one thing, they are inured to the hardships of the forest,” rejoined the professor; “for another, these Bolivian Indians wage war with poisoned arrows shot from long blow guns. A man usually dies in a few minutes after such an arrow has struck him, unless medical attention is at hand. Armed with these weapons, the Indians creep up on their foes and noiselessly decimate an entire force. It is in this way that the Indians have managed to reserve this part of the country for themselves and keep the hated white man out of it.”

The boys looked rather grave as they continued their tramp back to the Discoverer.

“Looks to me as if we were in for a more exciting time than we bargained for,” observed Nat to Joe.

“I guess you are right,” rejoined Joe. “A battle with Indians who employ such deadly weapons does not appeal to me.”

“Oh, I guess we’ll get through without trouble,” exclaimed Nat. “At any rate, if we are attacked, we can climb aboard the good old Discoverer and soon be out of range.”

“That’s so,” agreed Joe, and the lads dismissed the matter from their minds; but whether Nat’s surmise was correct or not, we shall see in due time.