Fear has taken over the island: right at the start of the chapter, remembering (for one of the final times in the novel) their old life at school, Samneric laugh, and then suddenly stop laughing:

The twins shared their identical laughter, then remembered the darkness and other things and glanced round uneasily.

Their fear, when they think they have seen the beast, becomes directly translated to Ralph, who like them has just been dreaming of his old home.

'Piggy-where are the spears?'

'I can hear the-' 'Quiet then. Lie still.'

They lay there listening, at first with doubt but then with terror to the description the twins breathed at them between bouts of extreme silence. Soon the darkness was full of claws, full of the awful unknown and menace.

The request for the spears, and the blossoming of the idea of the beast is the key factor which allows Ralph and Piggy's civilised law and order to crumble entirely. This is symbolised when Ralph does not blow, but only raises the conch - his fear of the beast prevents him from making a loud noise. The beast has overtaken the law:

Ralph took the conch from where it lay on the polished seat and held it to his lips; but then he hesitated and did not blow. He held the shell up instead and showed it to them and they understood.

This weakness is what allows Jack to take over at the meeting, and sow the seeds of his eventual rebellion - "We don't need the conch any more", he says, as the chapter draws to a close.