Their mentor, HHMI investigator Mark M. Davis, doesn't mind a bit. In fact, he encourages them, and proudly shows off the product of a protégé's doctoral thesis, which he unofficially titles, “Immune System: The Movie.” The student composed digital video recordings of immune cells going about their machine-like business—not unlike Hollywood's “Terminator”—of seeking out, recognizing, and destroying (or stimulating) other cells.

Illustration: Jonathon Rosen