Before Tom and Ned reached the place whence Professor Bumper had called, they heard strange noises, other than the imploring voice of their friend. It seemed as though some great body was threshing about in the jungle, lashing the trees, bushes and leaves about, and when the two young men, followed by Mr. Damon, reached the scene they saw that, in a measure, this really accounted for what they heard.  
Something like a great whip was beating about close to two trees that grew near together. And then, when the storm of twigs, leaves and dirt, caused by the leaping, threshing thing ceased for a moment, the onlookers saw something that filled them with terror.
 
Between the two trees, and seemingly bound to them by a great coiled rope, spotted and banded, was the body of Professor Bumper. His arms were pinioned to his sides and there was horror and terror on his face, that looked imploringly at the youths from above the topmost coil of those encircling him.
 
"What is it?" cried Mr. Damon, as he ran pantingly up. "What has caught him? Is it the giant iguana?"
 
"It's a snake—a great boa!" gasped Tom. "It has him in its coils. But it is wound around the trees, too. That alone prevents it from crushing the professor to death.
 
"Ned, be ready with your rifle. Put in the heaviest charge, and watch your chance to fire!"
 
The great, ugly head of the boa reared itself up from the coils which it had, with the quickness of thought, thrown about the man between the two trees. This species of snake is not poisonous, and kills its prey by crushing it to death, making it into a pulpy mass, with scarcely a bone left unbroken, after which it swallows its meal. The crushing power of one of these boas, some of which reach a length of thirty feet, with a body as large around as that of a full-grown man, is enormous.
 
"I'm going to fire!" suddenly cried Tom. He had seen his chance and he took it. There was the faint report—the crack of the electric rifle—and the folds of the serpent seemed to relax.
 
"I see a good chance now," added Ned, who had taken the small charge from his weapon, replacing it with a heavier one.
 
His rifle was also discharged in the direction of the snake, and Tom saw that the hit was a good one, right through the ugly head of the reptile.
 
"One other will be enough to make him loosen his coils!" cried Tom, as he fired again, and such was the killing power of the electric bullets that the snake, though an immense one, and one that short of decapitation could have received many injuries without losing power, seemed to shrivel up.
 
Its folds relaxed, and the coils of the great body fell in a heap at the roots of the two trees, between which the scientist had been standing.
 
Professor Bumper seemed to fall backward as the grip of the serpent relaxed, but Tom, dropping his rifle, and calling to Ned to keep an eye on the snake, leaped forward and caught his friend.
 
"Are you hurt?" asked Tom, carrying the limp form over to a grassy place. There was no answer, the savant's eyes were closed and he breathed but faintly.
 
Ned Newton fired two more electric bullets into the still writhing body of the boa.
 
"I guess he's all in," he called to Tom.
 
"Bless my horseradish! And so our friend seems to be," commented Mr. Damon. "Have you anything with which to revive him, Tom?"
 
"Yes. Some ammonia. See if you can find a little water."
 
"I have some in my flask."
 
Tom mixed a dose of the spirits which he carried with him, and this, forced between the pallid lips of the scientist, revived him.
 
"What happened?" he asked faintly as he opened his eyes. "Oh, yes, I remember," he added slowly. "The boa——"
 
"Don't try to talk," urged Tom. "You're all right. The snake is dead, or dying. Are you much hurt?"
 
Professor Bumper appeared to be considering. He moved first one limb, then another. He seemed to have the power over all his muscles.
 
"I see how it happened," he said, as he sat up, after taking a little more of the ammonia. "I was following the iguana, and when the big lizard came to a stop, in a little hollow place in the ground, at the foot of those two trees, I leaned over to slip a noose of rope about its neck. Then I felt myself caught, as if in the hands of a giant, and bound fast between the two trees."
 
"It was the big boa that whipped itself around you, as you leaned over," explained Tom, as Ned came up to announce that the snake was no longer dangerous. "But when it coiled around you it also coiled around the two trees, you, fortunately slipping between them. Had it not been that their trunks took off some of the pressure of the coils you wouldn't have lasted a minute."
 
"Well, I was pretty badly squeezed as it was," remarked the professor. "I hardly had breath enough left to call to you. I tried to fight off the serpent, but it was of no use."
 
"I should say not!" cried Mr. Damon. "Bless my circus ring! one might as well try to combat an elephant! But, my dear professor, are you all right now?"
 
"I think so—yes. Though I shall be lame and stiff for a few days, I fear. I can hardly walk."
 
Professor Bumper was indeed unable to go about much for a few days after his encounter with the great serpent. He stretched out in a hammock under trees in the camp clearing, and with his friends waited for the possible return of Tolpec and the porters.
 
Ned and Tom made one or two short hunting trips, and on these occasions they kept a lookout in the direction the Indian had taken when he went away.
 
"For he's sure to come back that way—if he comes at all," declar............