o forward
and press the grooved panel upon the wall in front of you."

* * * * *

Nat stepped forward, found the panel, and pressed it. The wall swung
open, like two folded doors, revealing another room within, perfectly
circular.

It contained a quantity of pieces of apparatus, some glowing with
light, some dark, and a radio transmitting set; it was evidently the
secret lair of the Black Caesar. And there he was, trapped at last by
the mortal illness that had overtaken him!

He was lying upon the couch, his great form stretched out, his
features hideously swollen by the same disease that had attacked the
guards.

Nat raised his ray-rod, but Axelson feebly put up his hand, and Nat
lowered the weapon. And, as the five gathered about the dying man,
again Nat felt that strange sense of pathos and pity for him.

He had never known Earth life, and he was not to be measured by the
common standards applicable on Earth.

"Don't fire, Nat," said Madge in a shaky voice. She was seated beside
Axelson, and--the wonder of it--she was sponging the foam from his
lips and moistening his forehead. She raised a crystal that contained
some fluid to his lips, and he drained it greedily.

"So--Earth wins, Nathaniel Lee," whispered Axelson hoarsely. "I am
dying. I know it. It is the same dreaded disease that came to the Moon
at the time of my father's landing there. Three-fourths of the Moon
animals died. It is mortal. The lungs burn away.

"My father told me that on Earth it is not mortal. He called it
'cold'--but I am burning hot."

Then only did Nat understand, and the irony of it made him catch his
breath and grit his teeth to check his hysterical laughter. The Black
Caesar, the terror of Earth, was dying of a common cold which he
himself had given him.

The coryza germ, almost harmless on Earth, among a population
habituated to it for countless generations, had assumed the potency of
a plague here, where no colds had ever been known--among the Moon men,
and even among the guards, after their lifetime in the germless
climate of Eros.

"I've failed, Nathaniel Lee," came the Black Caesar's voice. "And yet
that hardly troubles me. There is something more that I do not
understand. She is a creature like ourselves--with will and reason.
She is not like the Moon women. She told me that she did not wish to
be queen of the Earth because she did not love me. I do not
understand. And so--I am glad to