BOB shook his head to rid himself of the sickening saliva. He wiped his face with his handkerchief, with his hands, with anything he could find. At the same time he stepped out of reach of the treacherous animal.

When he had completed rubbing, he turned sheepishly to Joe.

“Guess I learned my lesson,” he said quietly. “But who’d ‘a’ thought it of the brutes?”

“Isn’t wise to do anything unless you know what you’re doing,” Joe reminded him.

“I’ve a notion to go over and wring its neck!” snorted Bob, glancing at the llama, which had resumed its grazing as if nothing had happened.

“Better not,” Joe warned him. “You might not be able to do it. And the Indian that owns them might come out.”

“Let him come!” Bob was confident that he could manage both the llama and the Indian.

He decided to let the matter drop, however, and continue the walk about the plateau.

As the youths hiked farther, they passed the grassy region and came to a higher slope that was dotted with occasional patches of cacti, thorn bushes, and stunted trees. The Australian eucalyptus, a small tree, was abundant.

“Can’t raise anything here,” remarked Bob. “Almost as bad as it is on the Sahara Desert.”

The chums made a wide circuit about Cuzco, coming in sight of the monoplane from the opposite side.

“You’re just in time to stand guard,” Mr. Holton told Bob. “And while you’re doing that, the rest of us will look around a bit. We’ve all been busy studying maps of the Andes.”

The adventurers took turns watching the airplane and seeing the country all during the remainder of that day. If it were able to follow schedule, the train from Mollendo, bringing the others of the expedition, would arrive the next afternoon.

At that time all the air travelers but Mr. Lewis were in the railroad station waiting. Mr. Lewis had remained at the field to guard the ’plane.

“It’s coming,” said Mr. Wallace, and a minute later the train pulled up and stopped.

Dr. Rust and the other scientists stepped off, to be met by the naturalists and the youths.

“I think it might be wise,” began Mr. Holton, “to establish a temporary camp here near Cuzco, perhaps in the field by the monoplane. Is everyone with me in this?”

Professor Allan nodded.

“I am in favor of it,” he said. “Until we make further preparations for our work in the mountains it would be wise to put up our tents there.”

At the field they found Mr. Lewis waiting for them. He also agreed to follow Mr. Holton’s suggestion.

Four tents were pitched in a semicircle beside the airplane. The expedition’s supplies were placed systematically inside, and then began a discussion about the coming exploration.

“We who are after Inca ruins have decided to set off for the region near Mount Panta,” Dr. Rust said. “In our opinion, there is an opportunity to find wonderful Inca remains in this section. Most likely we will stay within twenty miles of that mountain for three or four weeks. Where we will go then we will have to decide later.”

“Now of course you archÆologists want to know as nearly as possible where we naturalists will be,” began Mr. Holton. “I don’t know whether everyone will agree,” he went on, “but I know of a place that supposedly abounds with wild creatures. And I would suggest that we head for that spot.”

The others looked at him inquiringly.

“This morning while I was out scouting around I came across an American who was just returning from a hunting trip in the Andes,” Mr. Holton resumed. “He informed me that the valley of the Comberciato is teeming with wild game. According to his estimate, that’s about a hundred miles from here, northwest. It——”

“I’ve heard of it, too,” cut in Mr. Wallace, his face beaming with scientific enthusiasm. “Why not go there? We’ll probably find it worth our while.”

“I’m willing,” came from Joe’s father.

“Then let’s call it settled,” Mr. Holton said. “We’ll start out as soon as possible.”

“Here’s where Mr. Sutman and his airplane come in,” remarked Professor Allan. “By the use of the ’plane, we can keep informed as to the whereabouts of the other division of the expedition. It will prove a valuable asset to our equipment.”

Bob and Joe and Mr. Dunn took it on themselves to go back to the railroad station and have the many boxes of food and supplies removed to the camp. The scientists had purposely left them in charge of the agent until after deciding the course of the expedition and had carried only the lighter bags and cases to the camp.

The railroad agent, when asked of a means of transporting the boxes, pointed outside to a large cart drawn by a mule. Walking lazily at the side was an Indian.

“He will do it for you,” the railroad man said in poor Spanish.

Then, knowing that the Americans could not speak the Quichua language, the agent called to the native and asked if he would be willing to take the boxes.

The Indian merely nodded and went into the building after the first load. In all, there were about seventy-five cases, and he knew it would be necessary to make several trips.

“That mule doesn’t look any too willing to pull the load,” observed Joe with a laugh. “Be funny if he’d stop still when only about halfway there.”

When the cart was loaded with about fifteen or twenty of the boxes, the Indian called for the animal to pull ahead. But the stubborn mule refused to budge.

“Now what will he do?” mused Joe, looking at the impatient Indian.

He soon saw. The native removed five boxes and carried them back into the station. Then, with the cart lighter, he again attempted to make the mule move ahead.

But apparently it was still too much of a load, at least for comfort.

“That crazy donkey just doesn’t want to go, that’s all.” Mr. Dunn had been taking in the incident with a great deal of interest.

The Indian was becoming impatient. He had apparently removed all he was going to from the cart and intended to resort to force.

Walking to one side, he pushed with all his strength on the balky animal, at the same time saying something in Quichua that the whites guessed was not pleasant.

Slowly, very slowly, the mule struggled forward, snorting as if in rage. Gradually he quickened his pace, but never exceeded a walk.

“At this rate it’ll take us the rest of the afternoon to get everything in camp,” muttered Bob, amused and yet angered at the stubborn beast.

The youth guessed fairly right. The sun was almost ready to sink below the horizon when the last box was unloaded from the cart, after five trips had been made to carry all of the supplies.

“Too late to do anything tonight,” said Mr. Lewis, as the Indian, mule, and cart disappeared over the plateau. “I suppose we’d better take it easy, anyway. We’ll have some busy days ahead of us.”

Early the next morning the explorers were up preparing for the mountain journey.

“The first thing now is to get mules,” said Mr. Wallace. “And,” he added with twinkling eyes, “they’ll have to be faster than the one that carried our stuff last night.”

“You forgot.” Dr. Brown, the physician, was moving up to Mr. Wallace. “The first thing isn’t to get mules,” the doctor continued with a smile. “Medical attention always comes before anything else.”

“That means a physical examination?” asked Bob.

“Yes. And it also means vaccination against smallpox and typhoid fever. Those two diseases are very common in this part of Peru.”

Dr. Brown had attended to everyone but the youths and Mr. Wallace. But it did not take long to finish with them.

“Now as I was saying,” began Mr. Wallace, “the next thing is to get mules. And I know where we can find them. I inquired yesterday and found that a wealthy Peruvian who lives at the edge of Cuzco can let us have as many as we need. He will also see that we get native guides.”

“Don’t forget that we need about twenty-five mules—for both parties of the expedition,” Professor Allan reminded him.

“I haven’t,” the naturalist returned. “We can get as many as we need. Suppose we do it now.”

Mr. Wallace, Dr. Rust, and Professor Kelley set out at once to get the pack animals.

Meanwhile, Bob and Joe took movie cameras and walked leisurely up the hillside, intending to photograph anything that would come before them.

The boys had not gone far when they came upon a large group of Indian men, dressed in short, coarse trousers, hand-woven shirts, and brightly colored blankets. On their heads were the flat “pancake” hats which are common in this region.

“Here’s a good chance to take movies,” said Joe happily. He had brought the camera to his shoulder and pointed it toward the Indians, turning the crank steadily.

Suddenly the natives rushed angrily at the youths and made a grab at the motion-picture cameras.