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, nea