ppeared 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.

"You'll know all about it--soon! You'll know everything, but the
secret will still rest with Caleb Barter. Do not be too curious, my
friends."

"We are anxious to reach civilization, Professor," said Bentley,
deciding to be placative with the old man. "Perhaps you can arrange
for guides for us?"

Barter laughed.

"I could not permit you to leave me for some time," he said. "I want
you to witness my experiment. The world would never believe me without
the evidence of reliable witnesses."

Barter laughed again.

* * * * *

They entered a clean clearing which was a riot of flowers. At the
further edge was a log cabin of huge proportions. The whole thing had
a decidedly homely appearance, but it was a welcome sight to the
castaways. There were cages in which strange birds chattered shrilly
in their own language at sight of the three. A pair of tame monkeys
chased each other on the roof of the house, whose corners were almost
hidden by climbing vines whose growth one could almost see.

Barter led the way at a swift walk across the clearing and into the
house.

Bentley gasped. Ellen Estabrook exclaimed with pleasure.

The reception room was as neat as though it received the hourly
attentions of a fussy housewife. It was cozily furnished, yet it was
evident that the furniture had been made on the spot of rough wood
and skins of various animals. Deep skin rugs cove