What can you infer about Ralph's state of mind from this description? What has brought about this state of mind?

Earlier in the novel, Ralph was surprised to discover that he had begun to bite his nail. In chapter 8 this passage appears:

''Ralph sat down and began to poke little holes in the sand. He was surprised to see that one had a drop of blood by it. He examined his bitten nails closely and watched the little globe of blood that had gathered where the quick was gnawed away.'' (145)