[93] See Animal Magnetism, by Binet and Féré, in the International Science Series, and the references there given.
[94] In many cases the post-hypnotic performance of an enjoined action, or the experience of a post-hypnotic hallucination, is associated with the partial recurrence of the hypnotic trance, or of some condition closely allied to it. Mr. Edmund Gurney has carefully investigated the question (Proc. S.P.R., iv. pp. 268-323. See also Delbœuf's article there quoted, "De la pretendue Veille Somnambulique," Rev. Phil., Feb. 1887), and has shown that, with some subjects, during the performance of the enjoined action a further command can be given, or a further hallucination imposed, and that the whole incident will have passed from memory a few seconds later. In the case of some persons hypnotised by Dr. Bramwell, and bidden to see after waking an imaginary scene in a crystal, I have myself observed that they retained no recollection a few minutes later of the scene which they had been describing; and in at least one case the subject at the time of the hallucination was apparently insensible to pain. On the other hand, as Mr. Gurney has pointed out (loc. cit., p. 270), "there are some cases in which no reason whatever appears for regarding the state in which the action is performed as other than normal," and the same remark apparently holds good of post-hypnotic hallucinations. And there are many persons who can see hallucinatory pictures in a crystal, a glass of water, etc., when in full health and in a perfectly normal condition. See Mr. Myers' article already referred to (S.P.R., vol. viii.).
[95] De la Suggestion, p. 29.
[96] La Somnambulisme provoqué, p. 233.
[97] Rev. de l'Hypnotisme, November 1886, p. 148.
[98] Professor Sully, to quote a recent instance, in his work on Illusions in the International Scientific Series (ed. 1887), devotes less than a page and a half to the discussion of the sensory hallucinations of normal life, and sums up the subject by saying that "when not brought on by exhaustion or artificial means, the hallucinations of the sane have their origin in a preternatural power of imagination" (p. 117).
[99] The question, which was worded as follows:—Have you ever, when believing yourself to be completely awake, had a vivid impression of seeing, or being touched by a living being or inanimate object, or of hearing a voice, which impression, so far as you could discover, was not due to any external physical cause?—was printed at the top of a schedule containing twenty-five spaces for the names and other particulars of those answering. Collectors were instructed not to select those of whom the question was asked; and to record alike negative and affirmative answers. In the case of an affirmative answer being received, further particulars were sought. For a full discussion of the various sources of error incident to an inquiry of this nature, and the precautions taken to avoid them, and for details of the results obtained, the reader is referred to the Report of the Committee, presented in a condensed form to the Congress of Experimental Psychology which met in London in 1892, and to be published in full in the Proc. S.P.R., vol. x., part 26 (forthcoming).
[100] There was ill-health alone in about 5 per cent., anxiety alone in about 11 per cent., and both ill-health and anxiety in about 1.7 per cent. of first-hand cases.
[101] Hallucinations occurring in the ambiguous state between waking and sleeping are called by some writers hypnagogic. For the purposes of our investigation, coincident hallucinations occurring at times when it is doubtful whether the percipient is fully awake, e.g., when he is in bed, are termed "borderland." Their evidential value is, of course, somewhat less than that of hallucinations occurring when the percipient is unquestionably awake. (See cases 57, 59, 65, 66, etc.)
[102] Including apparitions of persons not dead more than twelve hours, and not known by the percipient to be dead.