indrops against the sun, and all of the
bright, unattainable Christmas tree ornaments of his childhood.

So rapt was he that he scarcely heard the alarm. Yet he responded
automatically to the sound that now sent him scrambling into his
exposure suit. He fitted one varium-protected oxy-tank to his helmet and
tucked another one under his arm for Captain DeCastros.

This was superfluous, for DeCastros not only had donned his rig; he had
managed to recall to memory a few dozen vile, degrading swear words
gleaned from the sin-pits of Marronn, to hurl at Mr. Wordsley.

No one could have helped it, really. Ships under the Drive are insulated
from contamination clouds and everything else in normal space. The
substance polluting the ventilation system, therefore, must have been
trapped within their field since Vega. Now it had entered the ship
through some infinitesimal opening in the hull.

It was the engineer's job to find that break. It was not easy,
especially with DeCastros breathing down one's neck. Mr. Wordsley began
to perspire heavily, and the moisture ran down and puddled in his boots.

An hour passed that was like an age. The prognosis became known and was
not reassuring. This was one of the toxic space viruses, dormant at
absolute zero, but active under shipboard conditions. A species, in
fact, of the dread, oxygen-eating _dryorus_, which multiplies with
explosive rapidity, and kills upon penetration of the human respiratory
system.

Because of the leak in the hull, the decontaminators could not even hold
their own. Mr. Wordsley shuddered to note that ominous, rust-colored
cobwebs--countless trillions of _dryori_--already festooned the
stringers of the hull.

Another precious hour was taken from them. Mr. Wordsley emerged wearily
from the last inspection hole.

* * * * *

"Well?" DeCastros snapped. "Well--well?" His face was greenish from the
effects of the special, contamination resistant mixture that they were
breathing.

"I found the leak," Mr. Wordsley said.

"Did you fix it?"

"It was one of the irmium alloy plugs in the outer hull beneath the
pile. They were originally placed there, I believe, for the installation
of a radiation tester. The plug is missing, and I am sorry to say that
we have no extras. Anything other than irmium would melt at once, of
course."

"We have less than eight hours of pure air in the tanks," DeCastros
said. "Have you thought of that, you