HYPNOTISM : WHAT IT IS AND WHAT IT IS NOT. 765 



whicli migM readily be committed spontaneously, the subject 

 makes no comment upon it. If, however, he has been told to do 

 something ridiculous, he is usually a little ashamed of his act, and 

 looks silly and embarrassed ; or, if asked why he did such a fool- 

 ish thing, he invents a justification of some kind, and these ex- 

 cuses are often exceedingly amusing. 



It is possible, moreover, to give rise to post-hypnotic illusions 

 and hallucinations of the various senses. Hallucinations of sight 

 are perhaps more readily provoked than any other kind. A per- 

 son may be made to see a rose, a bright light, a cat, or a devil. 

 In short, in some persons almost every imaginable visual halluci- 

 nation may be provoked. Binet and Fdrd have tried to demon- 

 strate the peripheral character of visual hallucinations, by show- 

 ing that such hallucinations are doubled when the patient looks 

 through a prism. If, for example, a person has an hallucination 

 of a rose, he sees two roses on looking through a prism. Bern- 

 heim has shown conclusively that this discovery of Binet and 

 Fdrd is the result of an imperfection in their manner of experi- 

 menting, and that in reality a prism produces no effect whatever 

 on the hallucination. In experimenting on hysterical patients, 

 however, it is very easy to be deceived with reference to this 

 point, for when the prism is placed before their eyes they see at 

 once that everything looked at through it appears double, and 

 conclude, with hysterical shrewdness, that the hallucination ought 

 to be doubled likewise. In other words, they either consciously 

 or unconsciously apply their newly derived knowledge of the 

 effect of a prism to the hallucination. 



This assertion is supported by the following facts : If an hal- 

 lucination be called forth by suggestion in a hysterical patient, in 

 a room which is sufficiently dark to make the objects it contains 

 nearly or quite invisible, the hallucination is not doubled in look- 

 ing through a prism for the first time, for the subject is uncon- 

 scious of the fact that the glass through which he is looking has 

 the property of doubling the image of a real object. Repeat the 

 experiment in a light room, and the patient will state that she 

 sees the hallucination double. If the subject of the trial be an 

 unsophisticated child, and not an hysterical woman, the hallucina- 

 tion is in every instance single. 



The duration of post-hypnotic hallucinations varies considera- 

 bly in different cases, but is usually not greater than a few min- 

 utes. Instances are, however, recorded where they have lasted 

 hours, and even days. It must be remembered that post-hypnotic 

 hallucinations can only be induced in a moderate proportion of 

 somnambulists. 



I can not omit a few words about the state of the circulation 

 and respiration during hypnotic sleep. Braid noticed that, when 



