AT Bob’s words of surprise, Joe burst out laughing. Mr. Holton could not help joining him, although he tried to restrain himself.

“That was about the craziest thing you ever did, Son,” Mr. Holton said, as soon as he could get his breath. “I’m afraid friend policeman will never forgive you.”

Bob grinned.

“I——Wait. He’s coming to.” The youth bent over the prone man.

“W-w-what happened, boy?” he demanded, sitting up and rubbing his jaw. “World come to an end?”

His friends laughed still harder.

“You—you tell—him, Dad,” pleaded Bob, as soon as he could manage to utter the words.

Mr. Holton sobered himself as best he could.

“There’s been a mistake,” he said, keeping his face straight with difficulty, “a terrible mistake. It seems that Bob here mistook you for the thief, He was the one that knocked you out.”

The officer stared for a moment at Mr. Holton. Then his gaze fell on Bob, who was wondering just what would be the outcome of his misdeed.

“I’m sorry,” the youth apologized. “When I felt you rushing past me so wildly I thought sure you were the thief running away. I should have made sure, though.”

The policeman continued to gaze at Bob.

“Well, all I can say, boy,” he began at last, still rubbing his chin, “is that you whip up a wallop of a punch. You’re the first bird that’s ever put Pat Callahan cold, and that’s something. I ain’t no runt, you know.”

“I hope you’ll forgive me, sir,” Bob said. “I’m terribly sorry.”

“Forget it.” The officer gained his feet. “We’d better be thinking about that thief,” he went on, looking about the basement, “though I suppose he’s miles away from here by now.”

Joe ran hurriedly up the basement steps and dashed on through the house. He reached the front door in but a few seconds, and then looked out over the lawn.

Then he uttered a cry of anger, as he caught sight of the thief running madly toward his automobile.

“Stop!” Joe commanded, running in that direction.

Exerting himself to the utmost, the boy pursued the fleeing man. He was but a short distance away when the latter jumped into his car and started the engine, a moment later shooting away toward the road.

Joe made an unsuccessful attempt to mount the running board, but failed. Then, criticizing himself for not arriving at the scene sooner, he watched the car turn up the road.

Impulsively, he jumped into Mr. Holton’s sedan, but found that the key was not there.

“We’re licked,” he moaned. “No use going after him. His car could run circles around Mr. Holton’s, anyway.”

He waited a little while for his father and friends to appear, but when they did not, he again went into the house.

“Joe! See anything of the fellow we’re after?” The speaker was Bob, who had appeared at the top of the basement stairs.

“Yeah, but it didn’t do me any good,” the other youth answered, and then told of his pursuing the escaped man.

“So he got away, did he?” said the policeman. “Well, we’ll fix him. There’s a telephone in that front room there. I’ll call up headquarters and tell them to stop him.”

“Maybe the wires have been cut,” suggested Mr. Lewis.

Somewhat to their surprise, the telephone was in working order.

After calling the police station and giving a complete description of the fleeing man and the car he was driving, the officer moved that they make a thorough search of the house in the hopes of finding the stolen specimens there.

“We men will look in the basement,” said the officer. “You younger fellows can search the upper floor. If you find anything, let us know right away.”

“Leave it to us,” chuckled Joe, as he led the way up the stairway. “If that stuff is up there, we’ll find it.”

“Maybe he took it with him in the car when he left,” said Bob. “He was a long time in leaving, you know.”

The chums searched the upper floor thoroughly but could find no trace of the stolen specimens. They went back over the rooms once more, but could again find nothing.

“I’m afraid we’ll have to admit defeat,” Mr. Holton said, when the chums had made their way downstairs. “We’ve looked all over the place, but it’s no use. One thing seems apparent: the thief took the specimens with him when he escaped.”

The situation was indeed most disappointing. They had come to this isolated house confident that they could recover the box of stolen specimens. Then, when they were about to find them and arrest the thief, the tables were unexpectedly turned. It was most disheartening, to the naturalists especially.

Although they had searched every section of the house, they resolved to look once more, even though it had become necessary to switch on electric lights. They also looked through several outbuildings.

An hour later, however, it became evident that nothing was to be found. Tired and downhearted, the five left the house and got in Mr. Holton’s car, ready to admit defeat.

The policeman took his leave at the police station, and then the others drove on home.

“The last we’ll see of those valuable specimens, perhaps,” moaned Mr. Lewis, as he brought the automobile up in front of the houses.

“Don’t be too sure of that,” spoke up Bob, assuming an air of optimism. “Like that officer said, with radio and all the latest inventions, police can trail anyone nowadays.”

“That’s right,” agreed Mr. Holton. “I certainly hope he’s caught.”

“And that they do it before we leave for Africa,” added Mr. Lewis.

“Africa!” repeated Bob longingly. The coming expedition to the Dark Continent had been absent from his mind all the afternoon and evening. “You will take Joe and me with you, won’t you? Please say that we can go. We’ll do all we can for the expedition and won’t cause any trouble.”

“There’s no danger of your doing that,” Mr. Holton said at once. “In fact, there have been times when Ben and I were glad you were near. But the hazard of it all, boys!”

“You know, Howard,” began Mr. Lewis, “I’ve been thinking this thing over, and I believe the trip to Africa would do the boys a world of good.”

“Hurrah!” cried Joe impulsively.

“They are plenty old enough to look out for themselves,” Mr. Lewis resumed. “And we’ll have to credit them with a lot of initiative. Personally, I am in favor of letting them go with us.”

Joe looked at his father hopefully, although in some surprise.

Bob seized upon the opportunity at once.

“That’s the way to talk, Mr. Lewis,” he said. “You see how we came out on that expedition into the Andes Mountains. Were successful in about everything. And the moving-picture house was well pleased with the pictures we took. There’ll be another opportunity to make money taking movies of Africa—if we can go.”

Mr. Lewis rose from his chair.

“Suppose we talk the matter over with their mothers,” he suggested. “And it won’t be easy to get their consent, either. But we can see what they think of it.”

Mr. Holton was very much undecided about the matter of allowing Bob and Joe to go, but he consented to do as Mr. Lewis suggested.

“Then,” he said, addressing the chums, “we can let you know later how things stand. All right?”

“Sure,” Joe answered. He felt that there was a big chance of things going in his favor. “But please don’t talk against it to our mothers.”

Mr. Holton smiled, and then, at a call from the Lewis residence, the little party disbanded.