What does Jack say about the conch in "Lord of the Flies", and what is the relevance to the story?

The conch is a major symbol in the book.  It represents order and civilization, or at least the quest for it.  Ralph uses the conch in the first chapter and gathers all the surviving boys together when he blows it.  The boys decide that, in meetings, whoever is holding the conch is the one who may speak.  Thus the conch also represents power.  Jack lusts for power, so he respects the conch in the earlier chapters.  In chapter 8, when Jack and Ralph clash once again, Jack tries to take over as leader.  At a meeting, Jack takes the conch and speaks.  He tells the boys that Ralph is an ineffectual leader and he should be replaced.  Jack demands a new vote.  When he loses once again to Ralph, he is humiliated and frustrated.  He gently lays the conch on the ground before leaving the group and running down the beach. His act is a symbolic shift for the conch.  It will not represent power from now on; only a feeble left-over representation of once was a civilization.  By chapter 11, when Piggy is killed holding the conch, the shell has ceased to have any meaning. Jack no longer sees it as anything more than a shell.