Twice Harry went out in search of food and of an exit from the cavern.  The first time he was away for several hours, and returned exhausted and empty-handed and without having found any exit other than the one by which we had entered.

He had ventured through that far enough to see a group of Incas on watch at the other end.  They had seen him and sprung after him, but he had returned without injury, and at the entrance into the cavern where we lay they had halted abruptly.

The second time he was gone out more than half an hour, and the instant I saw his face when he returned I knew what had happened.

But I was not in the best of humor; his terror appeared to me to be ridiculously childish, and I said so in no uncertain terms.

But he was too profoundly agitated to show any anger.

“You don’t know, you don’t know,” was all he said in answer to me; then he added; “I can’t stand this any longer.  I tell you we’ve got to get out of here.  You don’t know how awful—­”

“Yes,” said Desiree, looking at me.

“But I can scarcely walk,” I objected.

“True,” said Harry.  “I know.  But we can help you.  There must be another exit, and we’ll start now.”

“Very well,” I said quite calmly; and I picked up one of the spears which we had carried with us, and, rising to my knees, placed the butt of the shaft against the wall near which I lay.

But Harry saw my purpose, and was too quick for me.  He sprang across and snatched the spear from my hand and threw it on the ground a dozen feet away.

“Are you crazy?” he shouted angrily.

“No,” I answered; “but I am little better, and I doubt if I shall be.  Come—­why not?  I hinder you and become bored with myself.”

“You blame me,” he said bitterly; “but I tell you you don’t know.  Very well—­we stay.  You must give me your promise not to act the fool.”

“In any event, you must go soon,” I answered, “or starve to death.  Perhaps in another twenty-four hours I shall be stronger.  Come, Desiree; will that satisfy you?”

She did not answer; her back was turned to us as she stood gazing across the stream into the depths of the cavern.  There was a curious tenseness in her attitude that made me follow her gaze, and what I saw left me with no wonder at it—­a huge, black, indistinct form that moved slowly toward us through the darkness.

Harry caught sight of it at the same moment as myself, and on the instant he turned about, covering his face with his hands, and called to Desiree and me to do likewise.

Desiree obeyed; I had risen to my knees and remained so, gazing straight ahead, ready for a combat if it were not a physical one.  I will not say that a certain feeling of dread did not rise in my heart, but I intended to show Desiree and Harry the childishness of their terror.

Nothing could be seen but the uncertain outline of the immense bulk; but the same penetrating, sickening odor that had before all but suffocated me came faintly across the surface of the stream, growing stronger with each second that passed.  Suddenly the eyes appeared—­two glowing orbs of fire that caught my gaze and held it as with a chain.