entley felt the cold chills racing along his spine as he listened to the old man's flow of words. He behaved well, but Bentley could feel in spite of that, that there was a hidden current of menace in the old man's behavior. He wished that Ellen would keep him talking, would somehow make sure of his identity. Perhaps the same thought was in her mind, for it had scarcely come to him when the girl spoke again.
"Before he disappeared Professor Barter wrote a learned treatise on—"
"I am Professor Barter, I tell you, young woman. But if you wish proof the title of the treatise was 'The Language of the Great Apes.'"
Ellen turned quickly to Bentley and nodded. She was satisfied that the man was the person he claimed to be. He didn't ask how Ellen happened to know about him, and Bentley himself considered the proof entirely lacking in conclusiveness. Anyone might know about the last treatise of Barter.
However, they could but await developments.
They followed Barter along the trail. Now and again apes challenged from the jungle, and Barter answered them with that strange laughter of his, or with a flow of gibberish that was like nothing human.
Bentley shivered. Barter, by his laughter, was identifying himself to the great anthropoids. But with his gibberish was he actually conversing with them?
"This experiment of yours," said Bentley when the period of silence became unbearable, "—won't you tell us about it?"
The old man cackled.