to sleep — all but the ape-man. Silently and powerfully he strained at the bonds which fettered his wrists.
The muscles knotted beneath the smooth, brown skin of his arms and shoulders, the veins stood out upon his temples from the force of his exertions — a strand parted, another and another, and one hand was free. Then from the jungle came a low guttural, and the ape-man became suddenly a silent, rigid statue, with ears and nostrils straining to span the black void where his eyesight could not reach.
Again came the uncanny sound from the thick verdure beyond the camp. A sentry halted abruptly, straining his eyes into the gloom. The kinky wool upon his head stiffened and raised. He called to his comrade in a hoarse whisper.
"Did you hear it?" he asked.
The other came closer, trembling.
"Hear what?"
Again was the weird sound repeated, followed almost immediately by a similar and answering sound from the camp. The sentries drew close together, watching the black spot from which the voice seemed to come.
