t
it's okay now."

The Millers and the girls listened to their recital with mixed horror
and relief that the effect of the cold had vanished so quickly. Dr.
Miller's brows were knit as he tried to puzzle out what had happened.

"You saw no projection beam, I assume?"

"Not a trace," Rick said emphatically.

"You were actually in the mist when this cold effect hit you?" Dr.
Miller asked.

"I was," Rick agreed. "How about you, Scotty?"

"Same. I was groping around trying to find something to get my hands on.
I was actually in the pool of water. Rick was on the edge of it."

Dr. Miller considered. "Even if your assumption about dry ice is
correct, Rick, that wouldn't explain the cold effect. If one touches dry
ice, it is cold enough to cause a burning sensation, but had dry ice
been used on you it would have taken chunks of it in contact with your
skin. You felt nothing solid, I assume?"

Both boys shook their heads.

"Then we can rule out dry ice. I can't imagine what hit you."

"The Blue Ghost," Barby said, and shuddered visibly. "This ought to
prove it, I guess."

Rick admitted it. "Ought to is right, but I'm stubborn enough to keep
looking for a rational explanation. I got some water from the pool.
Anyone want to look with me?"

They all did, and followed Rick to the kitchen. He set up the microscope
and plugged in the substage light, then found a well slide and placed a
drop of water on it. But examine the drop as he would, using the most
powerful magnification, he could see nothing but a bit of brown debris
that seemed to be a thread of withered alga.

He took another drop from the coke bottle and tried again with similar
results. He shook the bottle and placed a third drop on a clean slide.

Rick focused the microscope on the drop of water. Yesterday--or was it
the day before? He couldn't remember clearly he was so tired--the rock
basin had been literally swarming with paramecia and other forms of
life. Today, following the appearance of the ghost, the water from the
basin was as devoid of life as the planet Jupiter.

He moved the well slide from side to side, bringing different parts of
the drop under his lens. There was a tiny wisp of vegetable matter he
recognized as a dead bit of Riccia, and a few black threads of algae.

Rick shook his head in bewilderment. "Whatever the Blue Ghost is," he
stated, "it's a killer. The mob we saw is gone."

Dr. Miller took over the instrument and confirmed Ri