The infamous "n-word" epithet for Jim was apparently used before Albert Bigelow Paine. I found the phrase used in a review of _Puddn'head Wilson_ from _The Booklover's Magazine_ for February, 1904. The review was written by T. M. Parrott. I've misplaced the original message, but I hope that this helps whoever was asking about the origins of the term. Donna Campbell