Peter Rabbit had lost his appetite. Now when Peter Rabbit loses his appetite, something is very wrong indeed with him. Peter has boasted that he can eat any time and all the time. In fact, the two things that Peter thinks most about are his stomach and satisfying his curiosity, and nearly all of the scrapes that Peter has gotten into have been because of those two things. So when Peter loses his appetite or his curiosity, there is surely something the matter with him.