Dr. Calvin stopped him with an impatient gesture, "Please, Peter. This isn’t one of your petty laboratory problems. If we can’t determine the modified Nestor by some gross difference that we can see with the naked eye, one that there is no mistake about, we’re out of luck. The danger of being wrong, and of letting him escape is otherwise too great. It’s not enough to point out a minute irregularity in a graph. I tell you, if that’s all I’ve got to go on, I’d destroy them all just to be certain. Have you spoken to the other modified Nestors?"