All these details of the procedure - the enforced rest, relaxation of the muscles, the closing of the eyes, the monotonous tapping of the induction hammer, but more particularly the deep inspirations are intended to induce hypnotic sleep without the aid of suggestion. As far as the deep inspirations are concerned, Hartenberg considers that they set up a certain amount of hypersemia of the thoracic viscera with concomitant cerebral anaemia, which latter promotes the onset of sleep. Although Hartenberg avoids using the words sleep and hypnosis, the action of suggestion is not excluded from his procedure, as will be seen from the considerations given below.

The classification of hypnogenetic expedients into psychical and physical is merely theoretical (Forel, Levillain), and that for two reasons. In the first place, we cannot regard body and mind as two factors which are independent of one another.

Sense-stimuli, which affect the body, nearly always exercise a certain influence on the mind; the mind, on the other hand, can act upon nothing that has not previously entered it by means of the organs of sense. In the second place, in practice several hypnosigenetic processes are used at the same time. This will become perfectly clear if the hypnotized person is watched; let him be told that he must concentrate his whole attention on the idea of sleep, and he will then, in order to obey the command, look steadily at some point, or at once shut his eyes, in order as much as possible to prevent distraction of thought.

Thus Bernheim occasionally uses fixed attention in addition to the mental methods. Braid, again, who made use of fixation almost entirely, considered a particular mental activity also necessary. This is to be particularly noticed, because some people nowadays believe that they are using the method of Braid when they tell the subject to look steadily at something. In reality, Braid considered a steady attention as well as a steady gaze indispensable if hypnosis were to be attained; the subject must think steadily of the thing he was looking at, and must not allow himself to be diverted from it. According to Braid, one can hypnotize even in the dark.

But even theoretically we cannot always keep these things apart. Closing of the eyes, with perhaps slight pressure upon them, often leads, as Lasegue showed, to hypnotic states. How these come about, whether through the cessation of the sense-stimulation or through the idea of sleep, which the closing of the eyes certainly easily calls up, cannot be decided.

After these details, the much discussed and disputed question must be answered, whether a person can be hypnotized without his knowledge; whether any one can be thrown into the hypnotic state merely by sense-stimuli, without these arousing an image of the hypnosis. For a long time such an occurrence was held to be possible, until the Nancy school demonstrated an important source of error - viz., the possibility that suggestion may be used quite inadvertently. At all events I know of no well-authenticated case in which sense-stimulation has produced hypnosis by a purely physiological action, Most people upon whom such experiments are made know that an attempt is being made to hypnotize them; they have been already hypnotized, and the stimuli arouse conscious or unconscious mental images of the hypnosis; or they have seen the same experiments with others, or have heard of them. Even when this is not the case, the objection raised by Bernheim and Forel remains to be considered - that the sense-stimuli induce a feeling of fatigue, and through this induce the hypnosis.

Which of the above methods, or which combination of them is the best for practical use, is a question the answer to which cannot readily be supplied. When we find that Richet thinks he can throw nearly everybody into the hypnotic state by means of mesmeric passes, that Liebeault, Bernheim, and Forel hypnotize nearly all their patients by the Nancy process, Vogt by his fractional method, and that Braid hypnotized ten out of fourteen by means of fixation, we see that different methods bring about nearly identical results. From this it follows that the success or failure of an experiment does not depend solely on the external influences which may be brought into play. The mental susceptibilities of the individual to be experimented on are of far greater importance, and consequently in each individual case that method should be selected which is most suited to the mental condition of the subject, for some persons appear refractory to one method while another succeeds. I have found persons insusceptible to the use of fixed attention, or to the method of Nancy, while I obtained results by mesmeric passes. Evidently this proves nothing against mental action, for many persons believe they can only be influenced by some particular process.

On the other hand, I have seen that intense fixity of gaze sometimes induces hypnosis when other methods are useless, perhaps because the subjective expectation of the hypnosis is sooner aroused by the long, intense stare than by verbal orders.

Chambard reckons chloroform, ether, etc., among hyp-nosigenic agents. Certainly many phenomena analogous to those of hypnosis have been observed in the sleep induced by these agents; but F. Myers, however, considers it better to distinguish the conditions thus produced from hypnosis. Attempts have recently been made, more particularly by Wetterstrand and Schrenck-Notzing, to study these phenomena. They conclude that by chemical substances like chloroform, morphine, haschisch, hypnosis can be attained in persons who are insensitive to other methods. Farez advocates the use of somnoform - a mixture of ethyl chloride, methyl chloride, and methyl bromide - for the purpose of inducing narcosis, during which suggestion may be used. Bernard, Feuillade, and Wiazemsky report good results from the use of somnoform. It would, however, be necessary to distinguish between cases in which deep sleep is first obtained by the use of drugs, and hypnosis from this condition, as Coste de Lagrave advises, and those cases in which the hypnotic phenomena are primary.