it mean? What _is_ a Naturalist, in your book?"

"Why, a radical thinker, of course. An opponent of government
policies, of progress. One who believes we're running out of living
space, using up the last of our natural resources."

"What do you suppose motivates Naturalists, really?"

"Well, they can't stand the pressures of daily living, or the
prospects of a future when we'll be still more hemmed in."

Ritchie nodded. "Any more than you could, a few months ago, when you
tried to commit suicide. Wouldn't you say that _you_ were thinking
like a Naturalist then?"

Harry grimaced. "I suppose so."

"Don't feel ashamed. You saw the situation clearly, just as the
so-called Naturalists do. And just as the government does. Only the
government can't dare admit it--hence the secrecy behind this
project."

"A hush-hush government plan to stimulate further breeding? I still
don't see--"

"Look at the world," Ritchie repeated. "Look at it realistically.
What's the situation at present? Population close to six billion, and
rising fast. There was a leveling-off period in the Sixties, and then
it started to climb again. No wars, no disease to cut it down. The
development of synthetic foods, the use of algae and fungi, rules out
famine as a limiting factor. Increased harnessing of atomic power has
done away with widespread poverty, so there's no economic deterrent to
propagation. Neither church nor state dares set up a legal
prohibition. So here we are, at the millennium. In place of
international tension we've substituted internal tension. In place of
thermonuclear explosion, we have a population explosion."

"You make it look pretty grim."

"I'm just talking about today. What happens ten years from now, when
we hit a population-level of ten billion? What happens when we reach
twenty billion, fifty billion, a hundred? Don't talk to me about more
substitutes, more synthetics, new ways of conserving top-soil. There
just isn't going to be _room_ for everyone!"

"Then what's the answer?"

"That's what the government wants to know. Believe me, they've done a
lot of searching; most of it _sub rosa_. And then along came this man
Leffingwell, with _his_ solution. That's just what it is, of
course--an endocrinological solution, for direct injection."

"Leffingwell? The Dr. Leffingwell whose name was on that photostat?
What's he got to do with all this?"

"He's boss of this project," Ritchie said. "He's the one who persuaded