The Ecitons, or foraging ants of Brazil are the terrors of the forests. Cases have been known in which these marching armies of myriads of the creatures have caused the desertion of entire villages. Animals, even the ferocious jaguar, flee before them, and birds and the minor forms of animal life give them a wide berth. They overwhelm by sheer force of numbers. One of their columns is like a stream of water. When it strikes an obstruction it spreads out till it has covered it. Then the relentless march goes on, leaving behind it devastation and death.

All these facts were known to Captain Sprowl from hear-say, and to Professor Von Dinkelspeil from his books. Yet neither of them had ever actually beheld one of the great movements of these creatures.

But Captain Sprowl’s warning to get out of the way came too late. The jungle on each side of the clearing was thick and too densely grown with thorn bushes and spined plants to permit escape in that direction.

Both paths out of the place were now blocked by the approaching armies advancing from opposite directions. To have attempted to pass by them would have been madness. In an instant anyone rash enough to face the columns would have been overwhelmed from head to foot by a tidal wave of Ecitons.

It was an awkward predicament. The armies approached closer every minute and it speedily became a matter of importance to secure some place of refuge.

The only one that offered was the mango tree from which the anaconda, whose carcass had attracted the foraging bodies, had made its last attack. Luckily, the branches grew close to the ground and it was an easy matter to clamber up into safety.

“Up with you all!” cried the skipper and then bent with a cry of pain.

One of the forerunners of the ant battalions had climbed up his leg and bitten him painfully on the calf.

“Consarn the critter!” roared the skipper, as he slapped his leg and killed his tormentor, “it stings like all Billy-go-long. I wouldn’t care to be sot on by a thousand on ‘em.”

This incident served to hasten their climb into the tree. Thanks to the low-hanging branches already mentioned, they were soon ensconced therein, and, as they thought, out of danger. From their different perches they eyed the scene below with interest.

As far as the eye could reach the ant columns extended. It was, of course, impossible to estimate the numbers in each advancing file, but there must have been millions upon millions of the tiny creatures. Insignificant enough in themselves as individuals, yet in this multiplicity of numbers they were calculated to inspire respect, even fear.

The forerunners reached the body of the snake a short time after the party had clambered into the tree. Within a few minutes the whole serpentine body of the reptile with its brilliant coloring was obscured by the moving mass of ants. They literally covered it from tip to tip and still fresh numbers appeared, till the ground seemed to heave with them, like a carpet placed on a draughty floor.

It was a fascinating sight, and the boys watched it with a deep interest not unmixed with awe. So densely were the tiny creatures packed that they appeared as one solid body rather than an enormous collection of individual Ecitons.

“Gracious!” exclaimed Tom, as they watched. “I hope none of them take a notion to come up here! They could make it mighty unpleasant for us if they did.”

“Onpleasant!” exclaimed Captain Sprowl, “that’s the word and then some, my lad. They’d drive us out of the tree and then——”

He waved his hand at the surging brown mass below in eloquent silence.

“’And the little ‘uns picked the bones—o-h-h-h!’” he sang dismally.

The professor, who was seated astride one of the lower limbs, interrupted at this juncture.

“Here iss luck!” he exclaimed. “Look, mein friends! I catch a fine spezimen!”

He held up in triumph the body of an ant that he had caught climbing up the trunk. It was fully two inches long and armed with a pair of immense forceps as related to the rest of its structure.

“Did that ant climb up the tree?” demanded the captain sharply.

“Ches! You didn’t dink dot it flewed up, hein?” asked the professor, popping the dead ant into his specimen box.

The boys laughed at this example of Teutonic wit. But Captain Sprowl did not appear amused. Instead he gave vent to a low whistle that sounded somehow indicative of dismay.

“What’s the matter?” asked Jack.

The captain, who sat next him on a bough above that occupied by the professor, placed his mouth close to Jack’s ear.

“Don’t say anything or scare the others,” he said earnestly in a hoarse whisper, “but if many of them takes a notion to climb this tree our name is D-E-N-N-I-S, Dennis.”

There came a sudden cry from the professor.

“Ach! here come some more. See, dey chase dot lizard oop der tree. Vunderful! If I haf not see it, I not belief idt!”

He drew out a fair-sized flask and dropped some liquid on the two ants he had just succeeded in capturing.

The ants shriveled up instantly. The touch of the stuff had killed them.

“What’s that stuff?” asked Captain Sprowl sharply.

“Ah! Idt iss a new sordt of insect killer,” cried the professor triumphantly; “der invention of a Cherman. Idt iss too powerful for ortinary use. Idt is only soldt to naturalists.”

“Say, let me have that bottle a minute, will you?” exclaimed the captain quickly.

“Der boddle? Vot for?”

“’Cause in about ten minutes, if we don’t do something to keep ‘em off, the ants is going to be as thick in this tree as they are below,” was the sharp reply. “Look down there now. They’re coming already. Jack, get down below and lend the professor a hand to keep them off.”

Jack did as he was told. He saw that the captain had conceived some plan of using the insect killer in case of an attack by the ants; and he soon realized that the situation called for quick and decisive action. Within a few minutes of his joining the professor, it was all he could do to brush back the invaders. His hands were stung fearfully; but both he and the professor kept bravely at their task.

“Keep ‘em back! I’ll be thar in a minute,” hailed Captain Sprowl, while a strong smell of chemicals filled the air.

With hands that bled from the tiny, powerful forceps of the invading ants, Jack and the savant kept at their task. But it was growing too much for them. In overwhelming numbers the tiny creatures were swamping them like an approaching tide.

“Hurry up!” cried Jack, “we can’t do much more.”

“Himmel! Dey are gedding vurse undt vurse!” roared the professor. “Ach! mein poor handts!”

“Never mind your hands,” admonished Jack, “we must keep them back.”

But every second the tree trunk grew more thickly covered with the ferocious little creatures. Beneath the circle that Jack and the professor managed to keep clear, they swarmed and surged furiously. Escape was out of the question. The travelers were going through an experience that has befallen many a castaway of the jungle. Bones have been found by searching parties, picked clean of flesh and bleaching, after the passing of an army of the marching ants.