who had
been adapted to similar conditions bred true and their progeny was
conditioned from birth to live under those conditions.

"Ten years later, ten years ago," the Head Teacher told us, "you
children were born. Born of parents carefully selected from those who
volunteered for the experiment. And from birth you have been brought up
under carefully controlled and gradually changing conditions.

"From the time you were born the air you have breathed has been very
gradually thinned and its oxygen content reduced. Your lungs have
compensated by becoming much greater in capacity, which is why your
chests are so much larger than those of your teachers and attendants;
when you are fully mature and are breathing air like that of Mars, the
difference will be even greater.

"Your bodies are growing fur to enable you to stand the increasing cold.
You are comfortable now under conditions which would kill ordinary
people quickly. Since you were four years old your nurses and teachers
have had to wear special protection to survive conditions that seem
normal to you.

"In another ten years, at maturity, you will be completely acclimated to
Mars. Its air will be your air; its food plants your food. Its extremes
of temperature will be easy for you to endure and its median
temperatures pleasant to you. Already, because of the five years we
spent in space under gradually decreased gravitational pull, the gravity
of Mars seems normal to you.

"It will be your planet, to live on and to populate. You are the
children of Earth but you are the first Martians."

Of course we had known a lot of those things already.

* * * * *

The last year was the best. By then the air inside the dome--except for
the pressurized parts where our teachers and attendants live--was almost
like that outside, and we were allowed out for increasingly long
periods. It is good to be in the open.

The last few months they relaxed segregation of the sexes so we could
begin choosing mates, although they told us there is to be no marriage
until after the final day, after our full clearance. Choosing was not
difficult in my case. I had made my choice long since and I'd felt sure
that she felt the same way; I was right.

Tomorrow is the day of our freedom. Tomorrow we will be Martians, _the_
Martians. Tomorrow we shall take over the planet.

Some among us are impatient, have been impatient for weeks now, but
wiser counsel prev