How does Bob Ewell's language, when he is giving testimony about the attack on Mayella, reveal his character and his feelings about his daughter?

Mr. Ewell is surly and crass in the witness chair, but the judge, who clearly does not respect the man, manages to keep everything orderly. Mr. Gilmer asks Mr. Ewell for his version of the events. Mr. Ewell claims that he heard Mayella screaming when he was coming in from the woods with kindling, and that he ran to the house to find Tom Robinson having sexual intercourse with her. He uses the highly offensive term "ruttin," which causes an uproar in the court. After the judge calms everyone down, Mr. Ewell says that he ran to get the sheriff. He implores the judge to "clean up" the "nigger-nest" that are his neighbors, claiming that his neighborhood is getting dangerous.

Atticus questions Mr. Ewell, asking whether a doctor was called, and Mr. Ewell again says that no doctor was called, saying that he has never called a doctor in his life and never thought of doing so. Atticus asks if Mr. Ewell remembers Mayella's injuries as being the same as described by the sheriff. Mr. Ewell says that he does. Atticus asks if Mr. Ewell can write, and he says he can, so Atticus asks him to write his name on an envelope. In so doing, it is revealed that Mr. Ewell is left-handed.