Some have also sought to induce hypnosis by the stimulus of heat - e.g., warm plates of metal (Berger).

I here mention in particular the so-called mesmeric, mesmerizing, or magnetic passes, upon which Richet sets great value. I have already shown and described above, in the second experiment, how they are made. It is not certain whether the stimulation of temperature, as Heidenhain and Berger suppose, or the slight motion of the air, or the mental influence, is the efficient agent in this case. I myself consider it most likely that the various agencies combine, but that the mental factor is the most important It is not necessary to assume the existence of any peculiar force, such as the magnetic fluid of the mesmerist.

I may here mention that the method of so-called "mesmeric passes" was not used by Mesmer; it is true that he endeavoured to influence by touch, but these peculiar, monotonous, long-continued passes which I have described above were unknown to him.

Pitres maintains that certain portions of the body are particularly sensitive to stimulation of the skin. The zones hypnoghus described by him sometimes exist only on one side of the body, sometimes on both. Stimuli applied to them are said to produce hypnosis in certain persons, as is indeed maintained of other parts. Among these parts of the body the crown of the head, the root of the nose, the elbows and the thumbs are mentioned. Crocq, of Brussels, is in agreement with Pitres as to the "zones"; but he says he has found other spots which vary with the individual. Crocq thinks that this enables him to eliminate "suggestion."

According to Chambord and Laborde a gentle scratching of the skin of the neck induces hypnosis. I myself have seen many persons who maintained that they became hypnotized only when I touched their foreheads. It is often stated that touches on the forehead induce a peculiar sleepy condition in many persons (Purkinje, Spitta). An Englishman named Catlow magnetized by means of gentle stroking of the forehead (Baumler). I also know some persons who, in order to go to sleep more easily, cause other parts of the body to be gently stimulated - the head, or soles of the feet, for example. Eulenburg maintains that pressure on the cervical vertebrae induces hypnosis. Boyd asserts that he once saw hypnosis induced by the introduction of a catheter into the male urethra; this was, of course, only a case of drowsiness in which sleep supervened later on. Herzog, commenting on Boyd's statement, has very properly pointed out that there could be no question of hypnosis in the case, which he explains as I have done.

Petersen includes the ovaries in the hypnosi-genetic zones.

Finally, I mention the action of the electric battery, whose influence, according to Weinhold, has the same effect as mesmeric passes; but Weinhold, however, does not consider that mental influences are in this case excluded. Eulenburg obtained a lethargic condition by galvanizing the head; but the person experimented on had already had attacks of lethargy, More recently Harrison Low states that he has seen hypnosis induced by the Rontgen rays. But we are justified in assuming that in all these cases in which hypnosis is supposed to have been caused by the means just mentioned, the hypnosis has only come on because the subject believed that the means employed induced hypnosis. Hirt often uses electricity in this way, but it is at the same time perfectly certain that it is not the electricity, but the subject's belief in its effect, that produces the hypnosis.

To conclude, I further mention stimulations of the muscular sense, such as the cradle-rocking used to send little children to sleep; I leave on one side the question as to whether hypnosis can be attained by this means. Similar states are said to be produced among uncivilized people by violent whirling or dancing movements: the movements are, however, accompanied by music and other mental excitations. The best known are the Aissaouas, in Algiers (Figuier, Bert, Delphin). "They carry on their business chiefly in the Algerian town of Constantine. They are able by means of dancing and singing to throw themselves into a state of ecstasy difficult to describe, in which their bodies seem to be insensible even to severe wounds. They run pointed iron into their heads, eyes, necks, and breasts, without injuring themselves" (Hellwald). The same thing is related of the Buddhist convents in Thibet (Hellwald, Gabriel Huc). It has often been pointed out that the monotonous singing and uniform whirling movements of the dervishes induce hypnosis in the performers.

I have, however, myself often watched the howling and dancing dervishes at Cairo and Constantinople without being able to detect any indication of hypnosis.

I have hitherto only spoken of sense-stimuli among the physical methods. But it must also be mentioned that the absence of these stimuli is likewise specified as an expedient for hypnosigenesis. Jendrissik, of Buda-Pesth, expresses the opinion that fixed attention is only effective because it causes fatigue of the nerves of sight, and consequently produces insensibility to stimulation. Striimpell observed a case in which a person fell asleep immediately on the cessation of sense-stimulation. A case of Ballet's, in which sleep and suggestibility were induced by closing the eyes and stopping the ears, probably belongs to the domain of hypnosis induced by suggestion; and I think that the same is true of the method described by Hartenberg in Paris, in 1900, by means of which hypnosis is supposed to be induced without suggestion being called into, play. Hartenberg lets the patient be comfortably seated, and then applies one electrode to his forehead and the other to his chest. The faradic current is then started, but without including the patient in the circuit. The subject is then told to take deep inspirations, and at the same time to concentrate his whole attention on his breathing; as soon as he begins to blink the experimenter closes his eyelids.