All these things have been done over and over for the last forty years, and people have not known whether to consider them a species of necromancy or well-practiced tricks, in which the performers were accomplices, or, perhaps, a few more thoughtful and better-instructed people have looked upon them as involving psychological problems of the greatest interest, which might some day strongly influence all our systems of mental philosophy. But whether done by the mesmerist of forty years ago or the hypnotist of the past decade, they were identical in character, and were simply genuine examples of the great power of suggestion when applied to persons under the mesmeric or hypnotic influence. Such exhibitions, however, are unnecessary and undignified, if not positively degrading, to both subject and operator, whether given by the self-styled professor of the town-hall platform or the aspiring clinical professor of nervous diseases before his packed amphitheatre of admiring students. One of the most singular as well as important points in connection with hypnotism is the rapport or relationship which exists between the hypnotizer and the hypnotized subject. The manner in which the hypnotic sleep is induced is of little importance. The important thing, if results of any kind are to be obtained, is that rapport should be established. This relationship is exhibited in various ways. Generally, while in the hypnotic state, the subject hears no voice but that of his hypnotizer; he does no bidding but his, he receives no suggestions but from him, and no one else can awaken him from his sleep. If another person interferes, trying to impose his influence upon the sleeping subject, or attempts to waken him, distressing and even alarming results may appear. The degree to which this rapport exists varies greatly in different cases, but almost always, perhaps we should say always, the condition exists in some degree. In some rare cases this rapport is of a still higher and more startling character, exhibiting phenomena so contrary to, or rather, so far exceeding, our usual experience as to be a surprise to all and a puzzle to the wisest. One of these curious phenomena is well exhibited in what is known as community of sensation, or the perception by the subject of sensations experienced by the operator. The following experiment, observed by Mr. Gurney and Dr. Myers of the Society for Psychical Research, will illustrate this phase of the subject. The sensitive in this experiment is designated as Mr. C., and the operator as Mr. S. There was no contact or any communication whatsoever of the ordinary kind between them. C. was hypnotized, but was not informed of the nature of the experiment which was to be tried. The operator stood behind the hypnotized subject, and Mr. Gurney, standing behind the operator, handed him the different substances to be used in the experiment, and he, in turn, placed them in his own mouth.