He had not felt it, but the eel had let go its hold on his leg, and had disappeared. But only for a moment. Suddenly, from somewhere near, its gleaming body writhed crazily, and a terrific twist of its tail hit Phil a glancing blow on the chest. He was swept under, and the water around him became a maelstrom. When next he bobbed to the tumultuous surface, he managed to get a much-needed breath of air--and in the swirling currents glimpsed the long, snake-like head of the eel go shooting by, with thin trickles of stuff that looked like white jelly clinging to it. That explained what was happening. The eel had been challenged by the ameboid monster, and they were fighting for possession of him--the common prey. * * * * * The water became an inferno of whipping and lashing movements, of whitish fibers and spearing thrusts of a glistening black electric body. Unquestionably the eel was using its numbing electric shock on its foe. Time and time again Phil felt the amoeba grasp him, searingly, only to be wrenched free by the force of the currents the combat stirred up. Once he thudded into the bottom of the river, and his lungs seemed about to burst before he was again shot to the top and managed to get a breath. At last the water quieted somewhat, and Phil, at the surface, saw the eel bury its head in a now apathetic mound of flesh. It tore a portion loose with savage jaws, a portion that still writhed after it was separated from the parent mass; and then the victor glided swiftly downstream, and disappeared under the surface.... Holmes floated helplessly on the inky water. He could see the amoeba plainly; it was still partly paralyzed, for it was very still. But then a faint tremor ran through it; a wave ran over its surface--and it moved slowly towards him once again. Desperately Phil tried to retreat. The will was there, but the body would not work. Save for a feeble flutter of his hands and feet, he could not move. He could not even turn around to bid Sue and David Guinness good-by--with his eyes.... Then a fresh, loved voice sounded just behind him, and he felt something tighten around his waist. "It's all right, dear!" the voice called. "Hang on; we'll get you out!" Sue had come in after him! She had grasped the rope tied to his belt, and she and her father were pulling him back to the bank! He wanted to tell her to go back--the amoeba was only feet away--but he could only manage a little croak. And then he was safe up on the ledge at the other side of the river. * * * * * A surge of strength filled his limbs, and he knew the shock was rapidly wearing off. But it was also wearing off of the monster in the water. Its speed increased; the ripplings of its amorphous body-substance became quicker, more excited. It came on steadily.