The English Society for Psychical Research and its American branch have of late years popularized "telepathy", or thought transference. A series of elaborate investigations were made by Messrs. Edmund Gurney, F. W. H. Myers, and Frank Podmore, accounts of which are contained in the proceedings of the Society. Among the European investigators may be mentioned Messrs. Janet and Gibert, Richet, Gibotteau, and Schrenck-Notzing. Podmore has lately summarized the results of these studies in an interesting volume, "Apparitions and Thought-transference, an Examination of the Evidence for Telepathy." Thought Transference or Telepathy (from _tele_--at a distance, and _pathos_--feeling) he describes as "a communication between mind and mind other than through the known channels of the senses." A mass of evidence is adduced to prove the possibility of this communication. In summing up his book he says: "The experimental evidence has shown that a simple sensation or idea may be transferred from one mind to another, and that this transference may take place alike in the normal state and in the hypnotic trance. * * The personal influence of the operator in hypnotism may perhaps be regarded as a proof presumptive of telepathy." The experiments show that mental concepts or ideas may be transferred to a distance. Podmore advances the following theory in explanation of the phenomena of telepathy: "If we leave fluids and radiant nerve-energy on one side, we find practically only one mode suggested for the telepathic transference--viz., that the physical changes which are the accompaniments of thought or sensation in the agent are transmitted from the brain as undulations in the intervening medium, and thus excite corresponding changes in some other brain, without any other portion of the organism being necessarily implicated in the transmission. This hypothesis has found its most philosophical champion in Dr. Ochorowicz, who has devoted several chapters of his book "De la Suggestion mentale," to the discussion of the various theories on the subject. He begins by recalling the reciprocal convertibility of all physical forces with which we are acquainted, and especially draws attention to what he calls the law of reversibility, a law which he illustrates by a description of the photophone. The photophone is an instrument in which a mirror is made to vibrate to the human voice. The mirror reflects a ray of light, which, vibrating in its turn, falls upon a plate of selenium, modifying its electric conductivity. The intermittent current so produced is transmitted through a telephone, and the original articulate sound is reproduced. Now in hypnotized subjects--and M. Ochorowicz does not in this connection treat of thought-transference between persons in the normal state--the equilibrium of the nervous system, he sees reason to believe, is profoundly affected. The nerve-energy liberated in this state, he points out, 'cannot pass