Instantly the aspect of the duel changed. For, upon the outrage of that assault, a fury not less insane than the maniac’s fired the professor, and he who always had prided himself upon a considered austerity of the emotions, was roused to the world-old, baresark thirst of murder which lies somewhere, black and terrible, in the soul of every courageous man, and, sends him, at the last, straight to the throat of his enemy. Power flushed through his veins; his muscles distended with the strength of steel. Driving his fingers deep under the chin, he tore the hideous, distorted face from his shoulder. His right hand, drawn back for a blow, twitched upon the cord from which depended his heavy poison-bottle. Shouting aloud, he swung up the formidable weapon and brought it down upon the juggler’s head with repeated blows. The man’s grasp relaxed. Back for a fuller swing Professor Ravenden leaped, and crushed him to the ground. The thick glass was shattered, and on the blood-stained sands a little spot of heaven’s blue fluttered in the breeze, instantly to be trampled under foot. Suddenly the scientist swayed and lurched forward. An influence as potent for death as the most murderous weapons of man was abroad, loosed when the glass shattered. The deadly fumes of the cyanide, rising from the base of the jar which its owner still held, were doing their work. With barely sense enough surviving to realise his new peril, he flung it far from him. A mist fell, like a curtain, somewhere between his eyes and his brain, befogging the processes of thought. Heavily he dropped to his hands and knees over the feet of the senseless juggler, his face toward Colton. Colton seemed to have risen. This the professor took to be a figment of his reeling brain. It annoyed him. “Lie down! Be quiet!” he muttered. “You are dead, and I am going to kill your murderer!” Calling up all his will-power, he crawled to the juggler’s head and set his fingers to the palpitating throat. Another moment and the death of a fellow-man would have been upon the soul of the scholarly scientist, when an arm under his chest and an insistent voice in his ear brought him back to reason. “In God’s name, Professor, don’t strangle the poor devil!” The baresark grip relaxed. Professor Ravenden collapsed, rolled over on his back and looked up stupidly into the white face of Dick Colton. “Where—where—is my _pseudargiolus?_” he asked plaintively. “It’s all right, professor; there wasn’t any _pseudargiolus_. Just lie quiet for a moment.” Professor Ravenden struggled up to a sitting posture. “Let me rise,” he cried. “I have lost my specimen of _pseudargiolus_. It fell when the jar broke.” He looked about him, and his eyes fell on the juggler. “The pteranodon?” he queried. The mist was clearing from his brain, and his mind swung dizzily back to the great speculation. “What does it all mean?” he groaned.