Why doesn't Ralph blow the conch when the meeting dissolves into chaos in the book Lord of the Flies chapter 5?

Ralph is worried that if he blows the conch and the boys fail to return it will spell the end of all hope of maintaining rules and common sense on the island. He feels that if they ignore the conch even once then they will ignore it permanently. By not blowing the conch Ralph hopes to avoid that situation. He feels that perhaps he can blow it the next day, in more normal circumstances, and that probably the boys will still obey the call.