Our author lays before the reader a summary of all the historic evidence available, together with a detailed record of his own experiments with this medium, conducted in Naples in November and December 1908. A complete resume of every theory that has been advanced to date, with a provisional hypothesis of his own. He then discusses at some length the biological and psychological peculiarities of the case, from the point of view of one who assumes, on the strength of the existing testimony, that the facts are established.