[Footnote 1: The work of the English bacteriologist Twort, in 1915, and the Frenchman, d'Herelle, in 1917, brought to the attention of the scientific world the fact that many bacteria are subject to attack and destruction by some unknown active agent with which they are associated in infected material. This agent, whatever its character, changed growing germ cultures to a dead, glassy substance. Twort advanced the thought that the agent might be a living, filtered virus, although he favored the theory that it was an enzyme derived from the bacteria themselves. D'Herelle, on the contrary, believed that this phenomenon was due to a living, multiplying, ultra-microscopic microbe that destroyed certain bacteria. Evidence favoring both theories has come to light, with the result that, at present, controversy is rife. Up to date, the contention of neither side has been proved.] Parkinson's adventure was almost at an end. He had not emerged unscathed, but he had won! The details of his further actions need not be recorded. Suffice it to say that he entered the sphere, carrying his precious, curative germs, arose to the top of the tower, and passed through a round opening in its side. His borrowed knowledge revealed that the car possessed abilities that he had not suspected; with amazing speed he caused it to flash across the Atlantic Ocean to the United States. There he saw the frightful carnage that the Plague had caused, saw the deserted cities--and was filled with self-reproach because he had not acted sooner. Across the miles and miles of deserted country he sped, following the fleeing hordes, finally passing over the stragglers and landing in the heart of the congested areas. After making a few inquiries, he returned to the sphere, and continued on toward the West. He landed, finally, outside the city of San Francisco. A short time later, twisted, deformed, yet triumphant, he was ushered into the presence of the United States government as--the man who had saved the human race. CHAPTER IV The terrible days of the Gray Plague ended in mystery. Much that had puzzled the world, Parkinson, with his Venerian knowledge, explained; but there was one thing, the final, enigmatical act in the strange drama, that was as much of a mystery to him as it was to the rest of the world. Enigma! Of what significance, of what portent--who could tell? When the great vessel from the United States, equipped to destroy the meteor of the Venetians, neared the great thoque sphere, they came upon a scene quite different from what they had expected. Parkinson, who was on the ship, was more surprised than the rest, for he had definite knowledge of what, in the natural course of events, they should see. For the others there was nothing so very strange in what they saw; Parkinson had lied, that was all.