He passed out into the laboratory. It was darker at this hour of dawn than at midnight with the moonlight in it. The sheeted figure still lay upon the slab. Was it a body obtained in the usual way, under the sanction of the law, or had it a criminal history? Nobody knew better than Nick the secrets that may lurk in the dissecting-room. With such thoughts, he paused a moment beside the body. He was about to lift the sheet in order to satisfy some doubts which still lingered in his mind when he was attracted by a slight noise in the cellar. He quickly stepped to the head of the stairs. Certainly there was some person below. Nick cautiously descended the steps. The electric lights were not shining, but the furnace sent up a glow in which the surrounding objects were dimly visible. The first of these objects to command Nick's attention was no other than the white face of Dr. Jarvis bending over the furnace. He had removed some portion of the arch above the raging fire, and just as Nick's eye fell upon him, he put a human arm into the white flame. In that fierce heat it was almost instantly consumed, and only the faintest smell of burning flesh escaped into the cellar. The corpse from which the arm had been taken lay upon the floor. Nick could not see it plainly, but his heart leaped wildly. There was but one explanation of Dr. Jarvis' conduct. Under the cloth in the laboratory above, Nick had seen the outline of a body. Whose, then, was this man giving to the flames? It could not be any but Chick's! Evidently the doctor had, by some fiendish trick, succeeded in overcoming his powerful watcher, and he was now removing all trace of the body, preparatory to his own flight to the ends of the earth. The horror of this thought was almost too much for Nick's iron nerves. If this was Chick's body, all human help was now vain. What should be done to secure the most certain retribution? Plainly the corpse, or what remained of it, must be recovered before the fire had completely made away with it. Nick was about to leap forward, and interrupt the dreadful work which was in progress under his eyes, when suddenly a new inspiration came to him. With a bound as noiseless as a tiger's, he was at the top of the stairs. In another instant he stood beside the sheeted form upon the slab. He withdrew the cloth. The body was Chick's. CHAPTER VI. THE LAST LINK IN THE CHAIN. Nick's first glance at the body of Chick took a weight like a mountain of lead off his heart. Chick was bound and gagged. This was enough to make Nick certain that no serious harm had come to him, but he was instantly made aware of it in another way. Cautiously Chick lifted an eyelid. A less acute observer than Nick would not have seen the movement. The eye opened wide, and then it winked. Chick was all right. "Shall I cut this rope?" asked Nick. Chick spoke straight through the gag with very little trouble.