pause. Relaxation. Tests. The black-clad figure spoke to one in yellow in a tone of pleased relief.

"Successful so far, Master Leithgow! We may congratulate ourselves on the consummation of the first step. It has been done, I believe, well within the time limit."

"Yes, Dr. Ku; yes. And now—how long will be needed to finish?"

"That is up to you. Normally, I would require a month. In that time all could be done safely, with small chance—"

"Too long!" said Leithgow.

Carse intervened:

"Why too long, Eliot?"

The old scientist went over close to him, and, in a lowered voice, explained:

"Ku Sui would develop immunity to the V-27 in a month. Two weeks of it would give him part immunity. Even ten days might. He has to be re-gassed four times a day."

"But, letting him come out of it every night and resting normally?" the Hawk objected.