Thanks to the excellent scholarship of BARB, I've found the quotation about
Mark Twain by Bret Harte in the Pemberton biography. It begins on page 73
and continues to the top of p. 75. The whole passage is well worth
reading. According to Margaret Duckett's MARK TWAIN AND BRET HARTE, Harte
told the story to Pemberton (p. 8).
Hooray for the Mark Twain Forum! Three Cheers for Barb!