ld be some guns and minor items.

Perhaps somebody could have predicted any of these items in advance,
but it was unlikely that anyone did. Nobody but Calhoun, however,
would ever have put them together and hoped very urgently that things
would work out. He could see a promising total result. In fact, in the
Med Ship hurtling through space, on the fourth day of his journey, he
thought of an improvement that could be made in the sum of all those
happenings when they got mixed together.

He got back to Dara. Maril came to the Med Ship. Murgatroyd greeted
her with enthusiasm.

"Something strange has happened," said Maril, very much subdued. "I
told you that sometimes blueskin markings fade out on children, and
then neither they nor their children ever have markings again."

"Yes," said Calhoun. "I remember that you told me."

"And you were reminded of a group of viruses on Tralee. You said they
only took hold of people in terribly bad physical condition, but then
they could be passed on from mother to child, until sometimes they
died out."

Calhoun blinked.

"Yes?"

"Korvan," said Maril very carefully. "Has worked out an idea that
that's what happens to the blueskin markings on Darians. He thinks
that people almost dead of the plague could get the virus, and if they
recovered from the plague pass the virus on and be blueskins."

"Interesting," said Calhoun, noncommittally.

"And when we went to Weald," said Maril very carefully indeed, "you
were working with some culture material. You wrote quite a lot about
it in the ship's log. You gave yourself an injection. Remember? And
Murgatroyd? You wrote down your temperature, and Murgatroyd's?" She
moistened her lips. "You said that if infection passed between us,
something would be very infectious indeed?"

"This is a long discussion," said Calhoun. "Does it arrive at a
point?"

"It does," said Maril. "Thousands of people are having their
pigment-spots fade away. Not only children but grownups. And Korvan
has found out that it always seems to happen after a day when they
felt feverish and very thirsty, and then felt all right again. You
tried out something that made you feverish and thirsty. I had it too,
in the ship. Korvan thinks there's been an epidemic of something that
is obliterating the blue spots on everybody that catches it. There are
always trivial epidemics that nobody notices. Korvan's found evidence
of one that's making _blueskin_ no longer a word wi