The papers here brought together have recently appeared in the 'Nineteenth Century' and the 'British Medical Journal, and are reprinted by permission. They are published to meet the wishes of some who have suggested to me it might prove useful and acceptable that they should be collected into a small volume, and thus become more available for current reference than they would otherwise have been. They were so favourably received at the time of publication that I may venture to hope it is not presumptuous to give them this more permanent shape. Nothing has been written in the way of criticism which seemed to me at all substantial, or to call for any modification of the text; so that while I can hardly hope that their somewhat aggressive tone will pass altogether without disapproval from a certain school of psychical researchers, yet I may venture to think that they will now, as they did when first published, meet with general acceptance from the medical and scientific world, and that they will serve a useful purpose in dissipating some popular errors and a good deal of pseudo-scientific superstition, superimposed on a slender basis of physiological and pathological phenomena. They may be of some service, also, in unmasking a prevalent system of imposture which had imposed upon a good many journalists and men of literary culture.

ERNEST HART.

88 WiMpolE Street, W. March 1898.