As far as its mode of production is concerned, hypnotic sleep does not essentially differ from natural sleep, of which it is in fact only a modification, and all the causes which produce fatigue are capable of producing hypnosis in those who are subject to it; it is in this sense that we may say with Richer, that all means are effectual, if only they are applied to a predisposed organism.
Sensorial excitements produce hypnosis in two ways: when they are strong and abrupt, or when they are faint and continued for a prolonged period.
The former mode of excitement was studied for the first time by Charcot and his pupils, who employed, among other means, vivid impressions on the sight, such as the sudden introduction of a solar lamp into a dark room, fixing the eyes on the sun, the incandescence of a strip of magnesium, the electric light, etc. In hysterical subjects the intense excitement immediately produces catalepsy. If the patient is seated at work, is standing, or walking, she is transfixed in the attitude in which she was surprised, and fear is expressed in her countenance and in her gestures. The same effect may be produced by an intense noise, like that of a Chinese gong, by a
whistle, or by the vibration of a tuning-fork. When the subject is predisposed, comparatively slight, but unexpected noises, such for instance as the crackling of a piece of paper, or the chinking of a glass, are enough to produce catalepsy.
If the excitement is moderate, rather than violent, it must be prolonged in order to cause the hypnotic sleep, which, however, it scarcely ever fails to produce. The subject is put to sleep after Braid's method, by fixing his gaze for a few moments on an object which may be slightly luminous, or altogether dark, such as a black stick, which should be held near the eyes and a little above them, so as to produce a convergent and superior strabismus. After a while the eyes become humid and brilliant, the gaze becomes fixed, the pupils are dilated. When the object is withdrawn, the subject remains in a cataleptic state; if it is not withdrawn, the subject soon falls backwards with a sigh, there is a slight frothing on the lips, and lethargy ensues. The convergence of the eyes alone will produce sleep, as for instance at night (Carpenter); some subjects fall asleep spontaneously when their eyes are fixed upon their needle-work, when they are reading, or looking in the mirror while dressing. Monotonous sounds also produce sleep. Weinhold and Heidenhain produced hypnosis by causing the subject to listen to the ticking of a watch; and a faint but continuous musical sound may produce the same effect. It is also well known that monotonous action on the hearing, a nurse's lullaby, the noise of the wind, the reciting of prayers, have a marked effect in producing natural sleep in many people.
It likewise occurred to us to produce a lethargic
sleep by fatiguing the sense of smell with a protracted odour of musk. No experiments have been made on the sense of taste. Tickling of the pharynx has succeeded with many subjects, but in this case it may be from complex reasons, since the subject nearly always fixes his eyes and keeps the thorax motionless.
Some facts appear to indicate that an excitement of the organs of the senses which does not act upon their special functions, but only mechanically, may produce like effects. Thus, when the eyeball is compressed through the closed lid, which was often done by Lasègue, hypnosis may be produced in some subjects, and a like effect may be produced by pressure on the external meatus of the ear. These modes of hypnotization belong, as we think, to the group of those which act by exhaustion of the special senses. In fact, a pressure on the eyeball, however slight, produces irritation at the base of the eye, whence there follows a sensation of light. When the external orifice of the ear is compressed, there is a pressure on the membrane of the tympanum by means of the air contained in the tube, and it may easily be shown that this causes a continuous murmur, which fatigues the sense of hearing, so that in this case also sleep results from exhaustion.
The hypnotizing processes in which a method involving contact with the skin is necessary, are, however, susceptible of more than one interpretation. We know that magnetizers formerly made use of what are termed passes; these passes consist in lightly touching the subject, either directly, or indirectly, through his clothes, and a prolonged repetition of these gestures produces sleep. Ch. Richet has ascertained that a gentle excite-
ment of the skin may produce the somnambulist sleep as well as the excitement of the special senses; yet it may be assumed that the success of the passes is greatly due to the psychical element.
We must note one interesting point in the history of hypnotizing processes, by means of irritation of the skin. On looking over the writings of magnetizers in the first half of the century, we are struck by the recurrence of certain gestures which contributed to discredit animal magnetism. It appears that the experimenter often caused his subject to sit down opposite to him, pressed his or her knees within his own, grasped the thumbs with his hands, and sometimes applied his forehead to that of the subject of experiment. These gestures, which appeared to be indecent, and unnecessary for the purpose he wished to effect, were in fact founded on accurate observations, which have since been verified.
It has been ascertained that when the scalp of hypnotized subjects is slightly irritated, the character of the sleep is changed. Thus, individuals plunged in the state designated by Charcot as lethargic or cataleptic, may be made to pass into the somnambulist state by a slight friction in the region of the scalp. Heidenhain, Grützner, and Berger, by slight and prolonged friction on one side of the heads of subjects in the waking state, have produced in them a unilateral hypnosis, displayed by an excessive muscular excitability. The influence of irritation localized in certain regions has recently been well described by Pitres, who has shown that in some subjects there are zones he terms hypnogenic, sometimes superficial, sometimes deeply seated, and that even a slight irritation of these zones may produce hypnosis,
or occasionally cause it to cease* Such zones may be found in all parts of the body, but most frequently in the vicinity of the joints, on the scalp, and especially on the forehead, and also at the root of the thumb. The legitimate observation of facts therefore justifies the gestures formerly in use, and we must not hastily condemn or deny that which we do not understand.
Irritation of the skin is as effectual when it is done with a feather, or some other inert body, as with the hand. We have ascertained that the sleep may be produced in several instances by placing a magnet close to an hypnogenic zone. We have also observed that the subject may put himself to sleep by pressing on such a zone. It should be added that each subject may display different hypnotic zones, not only as to their site, but as to their action; lethargy, catalepsy, and somnambulism may result in their several forms from the excitement of one or other of these zones.
Heat may produce the same effect as a mechanical excitement of the skin. Berger showed that he could produce hypnosis by holding his hot hands near the head of a person in a natural sleep; the heat disengaged from his hands produced this effect, for when he wore woollen gloves, or covered the sleeper's head, hypnotization did not occur. Berger also obtained like effects by placing metal plates, moderately heated, near the heads of his subjects.
An excitement which is not felt may have a hypnotizing effect, since consciousness is a super-added element, which is not essential. Thus the magnet, which acts as a peripheral excitement, may hypnotize a subject
without his perceiving the action exerted by this body on his organism. The influence of the magnet on hypnosis was first pointed out by Landouzy, in 1879, and the fact was afterwards verified by Chambard, and by the present writers.
Hypnotization by sensorial excitement, or by a physiological process, may be summed up as follows: —
1. By excitement of the sense of sight: (a) Strong and sudden excitement, by luminous rays, by solar or electric light, or by the sudden incandescence of a magnesium wire; (b) slight and prolonged excitement, by fixing the eyes on an object, brilliant or otherwise, ' which is placed near the eyes, and somewhat above their level.
2. By excitement of the sense of hearing: (a) Strong and sudden excitement, by a gong, by copper instruments, etc.; (b) slight and prolonged excitement, by the ticking of a watch, the vibrations of a tuning-fork, or any other monotonous sound.
3. By excitement of the senses of taste and smell.
4. By excitement of the sense of touch: (a) Strong and sudden excitement, by pressure on the hypnogenic zones; (b) slight and prolonged excitement, by passes, contact, action of heat or of the magnet.
These several physiological processes act very differently on different subjects. When used in combination, their effect may be greater or more rapid. Although, as Braid has shown, the operator's personality has not the importance which was formerly ascribed to it, yet it cannot be said to be altogether negative. It can easily be proved that some experimenters are more successful than others, at any rate with some subjects. This
elective phenomenon is not unimportant, and is perhaps partly due to the specific heat, smell, etc.
If this elective affinity exists in physiological processes, it is much more manifest in those processes which are psychical. In fact, hypnosis is not produced only by sensorial and peripheral excitement; it is also effected by central excitement, that is, by acting on the imagination. It may be asserted that, whenever the subject is warned that he is about to be hypnotized, his mind contributes to the success of the operation, and the sleep is partly due to psychical action.
The Abbé Faria, who induced sleep by intimation, has clearly shown that hypnosis may be effected by psychical action. His process consisted in desiring the subject, in an imperious voice, to go to sleep, and sometimes, without uttering a word, a commanding gesture was enough to effect his purpose. Faria's simple process is rarely employed, and insinuation is often substituted for intimation. Sleep may, for instance, be induced by telling the subject that he is sleepy or heavy, that his eyelids are closing, that he does not hear, nor see, etc., or — as we have ourselves observed — when the experimenter himself feigns to sleep. This gentle process is perfectly successful with subjects who have previously been hypnotized in other ways, and it succeeds at once with predisposed subjects, who have been under a course of treatment, and who feel confidence in the operator, and in the result of the operation. It is, in fact, only suggestion in the waking state.
This suggestion is often veiled by manoeuvres which formerly led to the belief that it was possible to magnetize from a distance. A susceptible subject could be put
to sleep by making passes through a door, if only the subject was aware that a magnetizer was present with that purpose in view. This experiment, intended to show that somnambulism is produced by a fluid which escapes from the magnetizer's body, and passes through opaque bodies, simply proves that the subject's fixed idea that he is being hypnotized is enough to put him to sleep, and this is a psychical impression. In this way it can be explained how a magnetizer in Paris can hypnotize one of his subjects in the country, when the latter is aware on what day and at what hour the operation is to begin; and, again, how some subjects are hypnotised by causing them to touch objects to which magnetic virtue has been openly ascribed. This likewise explains the action of magnetized water and magnetized trees. But the most striking experiment is the suggestion of sleep after a long interval of time. The subject is assured, with the necessary firmness and authority, that after so many days, at such an hour, he will spontaneously fall asleep. On the day appointed and at the given hour the suggestion is realized; the subject is overcome by sleep in the midst of his occupations, and in whatever place he may happen to be.
Several writers, who have observed the power of suggestion as an hypnogenic agent, have regarded it as universally present. Thus Braid asserts that the imagination of the subject is an indispensable element in the success of the experiment; he declares that the most expert hypnotizer will exert himself in vain, unless the subject is aware of what is passing and surrenders himself, body and soul. In our day, some authors have maintained that the expectant attitude was the cause of
all hypnotic phenomena, as well as of the phenomena of metallotherapeutics. Schneider and Berger consider that hypnosis is produced by a unilateral concentration of the attention. These assertions are too absolute. A whole series of purely physical agents exist, which prove that sleep can be induced without the aid of the subject's imagination, against his will, and without his knowledge.
We will mention, in conclusion, some of the experiments made by one of the present writers, * which confirm the idea already suggested by Braid, that hypnosis results from the exhaustion of the cerebral influx. An experimental proof can be given that all the sensorial excitements which induce hypnosis act by exhaustion, for the first effect of these excitements is an exaggeration of the motor phenomena. If the subject is made to hold a dynamograph in his right hand in such a way as to exert no pressure on it, and if he is then hypnotized, it can be ascertained that a motor discharge occurs in the interval between the excitement and the sleep. There is an intense pressure of the fingers on the dynamograph, and, indeed, the movement extends to all the muscles of the body. It is therefore probable that the hypnogenic excitement provokes an exhausting activity.
We are here met by the difficulty that the theory of exhaustion does not explain the sleep produced by suggestion. It has often been said that the psychical element in hypnosis vitiates all the attempts to give a physical explanation of this state. While admitting that the problem is difficult, we think it possible to
reconcile some psychical processes of hypnotization with processes due to exhaustion. All kinds of suggestion consist in making one idea predominant in the subject's mind; the suggestion of sleep is included in this category, and hypnotization is effected by the idea of sleep. Repeated experiments, which we shall afterwards mention in detail, show that every idea is an image, that every image recalls an anterior sensation. From this point of view, hypnotization by suggestion consists in hypnotization by physical excitements, not actually occurring, but remembered. In confirmation of this assertion, we give an example of an experiment communicated to us by Ballet. The suggestion was made to a subject, either in her waking state or in a previous sleep, of an electric lamp, shining from the comer of the room. The subject was awake and conversing tranquilly. When told to look in the corner where the imaginary lamp was placed, she was at once attacked by catalepsy, just as if the electric ray had shone upon her face. Hallucination, that is, the image of the luminous impression, produced the same effect as the actual impression, because it was recalled to her mind. So it seems probable that the suggestion of sleep only effects its purpose by inducing the recollection of certain impressions of fatigue which involve exhaustion in the same way as a physical excitement.
The awakening of the hypnotized subject, as well as his hypnotization, may be effected by two different processes — by a peripheral impression, or by a central and psychical impression. It is generally enough, in order to awaken the subject, to breathe lightly on his eyes or forehead. The wind from a pair of bellows may be substi-
tuted without inconvenience for breathing from the mouth, or a few drops of water may be sprinkled on the face. When these means fail, the subject's eyelids are opened, in order to breathe strongly on the corneae. And, in the case of hysterical patients, who do not. awake under this treatment, pressure is applied in the region of the ovarium. Pitres has also shown the existence of superficial zones in many hysterical subjects, which may be excited in order to awaken them. It is very probable that they might be awakened by addressing special senses, particularly those of sight and hearing. But nothing certain is known on these points. If the experimenter breathes on one half of the forehead, while sheltering the other half with a screen, only half of the body is awakened. The subject may also be awakened by a psychical impression. When the order to awake is repeated a certain number of times, the subject awakes, just as he goes to sleep when ordered to do so.
We see that there is a certain parallelism between the causes which produce hypnotism and those which remove it, and that in both cases it is done by excitement, whether of the surface of the skin, or of the special senses, or by a psychical excitement. This relation between the two processes is still more marked in some hysterical patients in whom there are found zones endowed with inverse properties, at once hypnogenic and the reverse. When the patients in question are awakened, an excitement of one of these zones, as for instance on the scalp, hypnotizes them, and an excitement of the same spot awakens them. In this case it may be said that the same cause has produced contrary effects, de- pending on the physical condition of the subject at the
moment of its action. But this is not a general rule. Some zones are exclusively hypnogenic; others are exclusively the reverse.
If there are numerous ways of producing hypnotism, their efficacy greatly depends upon the conditions. The first of these is habit. It has been justly observed that the first attempt to hypnotize a subject nearly always fails, and that it almost invariably succeeds when the experiment has been several times repeated. It is important to note this fact of hypnotic education. Although absolutely no effect may be obtained at the first séance, and the subject may declare that he experienced nothing, yet the attempt has impressed a permanent modification on his nervous system, which will render subsequent attempts more easy. At first the sleep is tardily produced, then it comes in a few minutes, next in a few moments, and finally almost instantaneously. After this, the subject is entirely in the magnetizer's power. It is interesting to observe that these facts are the expression of a general physiological law — the law of repetition. Numerous psychometrical experiments have shown; first, that when an act is frequently repeated, with sufficient intervals of repose, each series of repetition is accompanied by a shortening of the period of reaction; secondly, that this period becomes shorter in proportion to the increase in the number of repetitions; thirdly, that it is finally reduced to its lowest limit.
We now come to one of the questions most disputed at this time in the history of animal magnetism, namely, whether every individual is capable of hypnotization by the processes of which we have given a general account,
or if, in order to effect the result, a morbid predisposition must exist in the subject. Is there, to use Ladame's expression, an hypnotic neurosis, without which hypnotization is impossible, and are nervous diseases, and especially hysteria, to be regarded as the indispensable predisposition ?
We have already said that, as far as its production is concerned, artificial cannot be separated from natural sleep, and we will add that in its attenuated forms the one does not differ from the other in nature and character. We readily admit that artificial sleep may be produced in any subject by repeating, varying, and sufficiently prolonging the attempts, so as to induce fatigue. Before asserting that this result is impossible, these attempts should be made, and it logically rests with the sceptics to prove a negative. It is, however, certain that most nervous patients, and especially those suffering from hysteria, are distinctly predisposed to the hypnotic sleep, and that it differs from natural sleep by special physical characteristics.
It is precisely the addition of such characteristics which constitutes the most important part of the question, for these physical phenomena serve as the indication of the extremely complex psychical manifestations which accompany them.
Up to this time it has been asserted that physical phenomena, impressing a special character on the sleep, have only been observed in the hypnotism of hysterical patients, described by Charcot and Richer under the name of profound hypnotism. We admit that, in a great majority of cases, sufficient exhaustion to cause sleep may be artificially induced. But the following point remains
open to discussion: whether, because it is proved that an individual is artificially put to sleep, it necessarily follows that this is a special, not a natural sleep.
Even if this question should be decided in the affirmative, and it should be established that no one is absolutely refractory to hypnotism, we should feel justified in asserting that hypnotic phenomena consist in a disturbance of the regular functions of the organism. As Barth lately observed, it is possible to give every one a headache, but this does not prove that a headache is a physiological state. We do not therefore accept the opinion of those authors who treat hypnosis as a physiological state, and appear more anxious to separate it from other forms of neurosis, than to connect it with them. *
A second question is immediately connected with the former, namely, whether an individual susceptible to hypnotism can be hypnotized without his consent, and even against his will. Many persons are agitated by the idea that a stranger may influence and dispose of them as if they were mere automata. This is certainly dangerous to human liberty, and it is a danger which increases with the repetition of experiments. When a subject has been frequently hypnotized, he may be unconsciously hypnotized in several ways: first, during his natural sleep, by a slight pressure on the eyes; next, in the case of an hysterical patient, by surprising her when awake by some strong excitement, such as the sound of a gong, an electric spark, or even by a sudden gesture. Some curious anecdotes are told on this subject. An
hysterical patient became cataleptic on hearing the brass instruments of a military band; another was hypnotized by the barking of a dog; another, who had hypnogenic zones on her legs, fell asleep in the act of putting on her stockings. Even supposing that the subject knows that he is to be hypnotized, and desires to resist, this resistance will often be in vain, in spite of his urgent protestations, and he will soon submit to the authority which the experimenter has acquired over him. Sometimes, however, it has occurred to the subject that he will not sleep, and then the experimenter finds himself opposed by an idea which he is unable to modify; — neither the gong nor the electric light produces any effect, and pressure on the eyes, continued for hours, only brings on an attack of convulsions. If these fixed ideas are artificially developed, they form an almost complete obstacle to all attempts at hypnotization. Of this the patients are aware, and some- times, when they do not wish to be hypnotized by a given person, they cause their companions to hypnotize and suggest to them. Experimenters sometimes adopt similar expedients; and the caskets and talismans which have been given to patients, with the assurance that no one can hypnotize them while they carry these objects about, must be regarded as simply a mode of suggestion.
With respect to persons who have never been hypnotized, and to the question whether they can successfully resist the forcible attempt to put them to sleep, some authors have said that an individual can prevent any one from hypnotizing him, if he resists. The naivete of this assertion reminds us of those philosophers who say, " I am free to do thjs or that, if I wish it." Everything depends on whether the subject can exercise resistance
and use his will It must not be supposed that because moral resistance is a psychical function, it is found to an equal degree in all men. On the contrary, it varies with the individual, just as muscular force varies. The question does not therefore admit of a simple answer. In the case of a person who has never been hypnotized, and is not very susceptible to hypnotism, his consent, and even his good will are very necessary for the success of the operation, and without these he cannot be hypnotized. But some people are excessively susceptible, and in them the resistance is necessarily slight. They may be taken by surprise when naturally asleep and hypnotized by pressure on the eyes, and in the waking state they may be intimidated, taken by surprise, and may even receive dangerous suggestions without being put to sleep.* Such persons should guard themselves carefully, since the seriousness of the danger cannot be denied.