who do the author and jim burden discuss on the train and what is the result

On a train crossing the Midwest, Jim Burden, a successful lawyer working for the railroad in New York City, and an unnamed acquaintance (presumably Cather) reminisce about their childhoods growing up in Nebraska and about a mutual friend, Ántonia Shimerda who they believe exemplifies life on the prairie. Jim is challenged to write his memories of Ántonia and his upbringing and shortly delivers his memoir—which is largely the novel itself—to the acquaintance, who publishes it much as he has written it.