What does Pearl refuse to do? What must Hester do to persuade her?

In chapter 18 of The Scarlett Letter, Pearl stubbornly refuses to obey her mother's command to jump across the stream and make friends with the minister. Instead, the child points an accusing finger at the vacant spot on Hester's dress. She frowns, she stamps her foot. And when Hester begins to scold, Pearl throws herself into wild contortions and utters piercing shrieks that echo through the forest. Hester has no choice but to pacify Pearl. She knows what the child misses, and she wades into the stream to retrieve her.