But sound-seeing is only a conspicuous example of synæsthesiæ which exist in as yet unexplored variety. When we find that there are gradated, peremptory, inexplicable associations connecting sensations of light and colour with sensations of temperature, smell, taste, muscular resistance, etc., we are led to conclude that we are dealing, not with the casual associations of childish experience, but with some reflection or irradiation of specialised sensations which must depend upon the connate structure of the brain itself.
This view is consistent with the results of an Enquête sur l'audition colorée recently conducted by Professor Flournoy, from which it appears that of 213 persons presenting these associations only 48 could assign the date of their origin; and is supported by a case described in the Revue de l'Hypnotisme, December 1892, p. 185, where a man who had long exhibited a limited form of audition colorée developed gustation colorée in addition when in a low state of health.
See also the "Report of the International Congress of Experimental Psychology, Second Session, London, 1892," pp. 10-20 (Williams & Norgate, London, 1892), and the American Journal of Psychology for April 1900 (vol. xi. pp. 377-404).
[102] See Proceedings S.P.R., vol. viii. p. 480 [610 A].
[103] The "Census of Hallucinations" was undertaken in 1889, by a Committee of the S.P.R., under the direction of Professor Sidgwick, and consisting of himself and Mrs. Sidgwick, Dr. A. T. Myers, Mr. F. Podmore, Miss A. Johnson, and the present writer. The full report of the committee was published in 1894. (Proceedings S.P.R., vol. x. pp. 25-422.) A summary of the report is given in the original edition. [612 A.]
[104] For prehistoric and historic crystal-gazing see Mr. Andrew Lang's Making of Religion, and Miss Goodrich-Freer's "Recent Experiments in Crystal-Vision," Proceedings S.P.R., vol. v. p. 486 [620 A].
[105] It is right also to state, although I cannot here discuss the problems involved, that I believe these visions to be sometimes seen by more than one person, simultaneously or successively.
[106] See also Proceedings S.P.R., vol. i. pp. 263-283; vol. ii. pp. 1-5, 24-42, 189-200; vol. iii. pp. 424-452, where a full record will be found of Mr. Malcolm Guthrie's experiments [630 B]. Also Proceedings S.P.R., vol. xi. pp. 2-17 [630 C], for Mr. Henry G. Rawson's experiments. Others are recorded in the Proceedings S.P.R., vol. i. pp. 161-167 and 174-215. See also those of Herr Max Dessoir (Proceedings S.P.R., vol. iv. p. 111, and vol. v. p. 355); Herr Anton Schmoll and M. Etienne Mabire (ibid. vol. iv. p. 324 and vol. v. p. 169); Mr. J. W. Smith (ibid. vol. ii. p. 207); Sir Oliver Lodge (ibid. vol. vii. p. 374); Dr. A. Blair Thaw (ibid. vol. viii. p. 422); Dr. von Schrenck-Notzing (ibid. vol. vii. p. 3); Professor Richet (ibid. vol. v. p. 18). See also Phantasms of the Living, vol. i. pp. 32-34, and vol. ii. pp. 653-654. Also the experiments of Professor and Mrs. Sidgwick (Proceedings, vol. vi. and vol. viii.) already referred to in Chapter V.
[107] See Mr. F. Podmore's Apparitions and Thought-transference, Chapter V. [630 D, etc.]; also Proceedings S.P.R., vol. xi. p. 455 [630 F]; and Journal S.P.R., vol. vii. pp. 325-329 [630 E]: ibid. pp. 234-237, pp. 299-306 and pp. 311-319; and vol. xii. p. 223 (March 1906).
[108] It is plain that on this view there is no theoretical reason for limiting telepathy to human beings. For aught we can say, the impulse may pass between man and the lower animals, or between the lower animals themselves. See Journal S.P.R., vol. xi. pp. 278-290 and pp. 323-4; the same, vol. xii. pp. 21-3; the same, vol. iv. p. 289; and Proceedings S.P.R., vol. xiv. p. 285.