Naturally, I do 1 not contend that a hypnotic cannot find a paper in such a case better than a waking man. I only wish to point out that although this experiment is often used to demonstrate the presence of hyperesthesia, the latter is not generally necessary for its success. I have seen men of science show astonishment when a hypnotic distinguished apparently identical sheets of paper. They did not understand that there were essential differences in the sheets, which suffice for distinguishing them even without hypnosis. The experiment is to be explained thus: - The minute but recognizable differences (points de repere) presented to the hypnotic at the moment when the idea of the photograph was suggested to him, recall the suggested image directly he sees them again. The points are so closely associated with the image that they readily call it up. Binet and Fere have rightly pointed out that the image only occurs when the points de repere are recalled to the memory; they must first be seen. Consequently, if the paper is held at a distance from the subject's eyes, the image will not be recognized, for the points de repere are not visible.

Some of Binet and Fere's experiments are interesting. They have caused photographic impressions to be made of white papers on which a portrait had been created by means of suggestion. It was shown that the hypnotic always took the copies for the original, because the photographed point de repere aroused the same image in his imagination. Jendrassik has observed the same sort of thing; if a "d" is drawn with the finger on a sheet of white paper, and if it is suggested that the "d" is real, the subject sees the "d." If the paper is turned upside down he sees "p," and in the looking-glass "q." This is because certain points on the paper were remembered by the subject, and when the paper was placed in different positions the points appeared in different positions also.

In addition to increase and decrease of sense-perception, it is possible to induce all kinds of sense-delusions. The images produced are so remarkable that any one who sees them for the first time is justified in doubting whether the phenomena are real or not. We have accustomed ourselves to depend so completely on our organs of sense, to think them such trustworthy witnesses in all cases, that we are astonished to find that a word suffices to place a hypnotic among utterly different surroundings.

Sense-delusions are divided into hallucinations and illusions. The first is the perception of an object where there is really nothing; the second is the false interpretation of an existing external object. If, for example, a book is taken for a cat, or a blow on the table for the firing of a cannon, we talk of an illusion; but if a cat is seen where there is nothing, we call it a hallucination. We have thus to do with a hallucination when an external object causes a perception by means of association. A chair on which a particular person has often sat may by association call up an image of that person; this is a hallucination called up by an external object.

We observe numerous hallucinations and illusions in hypnosis. We have seen in Case IV. (p. 35) that it suffices to assert that a dog is present, and a dog will apparently be seen by the hypnotic. A handkerchief was in this case taken for a dog, consequently this was an illusion. An illusion is more easily induced than a hallucination; in the absence of an external object, such as the handkerchief, the suggestion very often fails. When I do not offer some such object the hypnotic often finds it for himself. Hallucinations of sight are more easily caused when the eyes are closed; the subjects then see objects and persons with their eyes shut, as in dreams. They think at the same time that their eyes are open, just as we are unaware in dreams that our eyes are shut. If we wish to cause a delusion of the sense of sight at the moment of opening the eyes, it is necessary to make the suggestion quickly, lest the act of opening the eyes should awaken the subject. I advise the use of fixed attention while the suggestion is being made (cf, Exp. IV., p. 35), so that the patient may not awaken himself by looking about. The other organs of sense may also be deluded.

I knock on the table and give the idea that cannon are being fired; I blow with the bellows and make the suggestion that an engine is steaming up. A hallucination of hearing something - e.g., the piano, is induced without the aid of any external stimulus. In the same way smell, taste, and touch may be deceived It is well known that hypnotics will drink water or even ink for wine, will eat onions for pears, will smell ammonia for Eau-de-Cologne, etc. In these cases the expression of the face induced by the suggested perception corresponds so perfectly to it that a better effect would scarcely be produced if the real article were used. Tell a person he has taken snuff, he sneezes. All varieties of the senses of touch, of pressure, of temperature, of pain can be influenced. I tell a person that he is standing on ice. He feels cold at once. He trembles, his teeth chatter, he wraps himself in his coat. Even "goose-skin" can be produced by the suggestion of a cold bath (Krafft-Ebing). In like manner, itching and so forth can be induced. I say to a gentleman, "To-morrow at three o'clock your forehead will itch." The post-hypnotic suggestion proves true; the forehead itches so much that the subject rubs it continually.

I find that the senses of taste and touch are more easily influenced than the others. The suggestion of a bitter taste, or of increased sensitiveness to temperature on the part of the skin, takes effect much sooner than the suggestion of a delusion of sight or hearing. Certainly we do know that even without hypnosis the senses of taste and temperature are more readily affected by suggestion than those of sight and hearing. Similarly, delusions of the senses of taste and temperature appear in the first stage of hypnosis (just as they do in the waking state), whereas conspicuous delusions of sight and hearing are only observed in deep hypnosis. Moreover, it sometimes happens, especially in cases of light hypnosis, that a subject tastes the bitterness or feels the warmth suggested, although he is perfectly aware of the delusion. On one occasion a gentleman said to me: "I know there is nothing bitter in my mouth, and yet I have a bitter taste in it."