sex itself, primal and basic, the most widespread concomitant of life in
this continuum, is completely illogical and paradoxical. Most
baffling--decidedly, this research on sex must go on."

Roger pressed a button and a tall, comely woman appeared--a woman of
indefinite age and of uncertain nationality.

"Show Miss Marsden to her apartment," he directed, and as the two women
went out a man came in.

"The cargo is unloaded, sir," the newcomer reported. "The two men and
the five women indicated have been taken to the hospital."

"Very well, dispose of the others in the usual fashion." The minion went
out, and Roger continued, emotionlessly:

"Collectively, the other passengers may be worth a million or so, but it
would not be worthwhile to waste time upon them."

"What are you, anyway?" blazed Costigan, helpless but enraged beyond
caution. "I have heard of mad scientists who tried to destroy the Earth,
and of equally mad geniuses who thought themselves Napoleons capable of
conquering even the Solar System. Whichever you are, you should know
that you can't get away with it."

"I am neither. I am, however, a scientist, and I direct many other
scientists. I am not mad. You have undoubtedly noticed several peculiar
features of this place?"

"Yes, particularly the artificial gravity and those screens. An ordinary
ether-wall is opaque in one direction, and doesn't bar matter--yours are
transparent both ways and something more than impenetrable to matter.
How do you do it?"

"You could not understand them if I explained them to you, and they are
merely two of our smaller developments. I do not intend to destroy your
planet Earth; I have no desire to rule over masses of futile and
brainless men. I have, however, certain ends of my own in view. To
accomplish my plans I require hundreds of millions in gold and other
hundreds of millions in uranium, thorium, and radium; all of which I
shall take from the planets of this Solar System before I leave it. I
shall take them in spite of the puerile efforts of the fleets of your
Triplanetary League.

"This structure was designed by me and built under my direction. It is
protected from meteorites by forces of my devising. It is indetectable
and invisible--ether waves are bent around it without loss or
distortion. I am discussing these points at such length so that you may
realize exactly your position. As I have intimated, you can be of
assistance to me if you will."

"Now ju