It is shown that rescatteriug effects required by unitarity can produce the reaction Do $F', even when the "8'-exchange" or "annihilation" diagram is not present. This is addressed both in a general context and a specific model. In the latter, it is the mode Do E"q which plays the major role in generating the @Efinal state, as the E'q state is produced using the uu component of the g, and scatters, I/' q E$, by quark exchange, utilizing the ss component of the q.