HYPNOTISM. 



573 



HYPNOTISM. 



By GEOKGE J. ROMANES. 



THE phenomena of " hypnotism," " mesmer- 

 ism," or "electro-biology," have of late 

 years excited so much popular interest — not to 

 say popular superstition — that their investiga- 

 tion by a competent man of science will appeal 

 to the sympathies of a wider public than the 

 purely scientific. My object, therefore, in writ- 

 ing the present article is to give a brief review 

 of a monograph on this subject, which has just 

 been published by the well-known physiologist, 

 W. Preyer, of Jena. 1 



In order to eliminate all possible effects of the 

 imagination, Preyer performed his experiments 

 only upon animals, and he begins his paper with 

 an historical sketch of previous investigations of 

 a similarly restricted nature. First we have the 

 " Experimentum mirabile " of the Jesuit Atha- 

 nasius Kircher, published by him in the year 

 1646. 2 This consists in taking a common fowl, 

 binding its feet together, and placing it on a floor. 

 As soon as it has ceased to struggle, a straight 

 line of chalk is drawn from the point of its bill 

 along the floor. If the legs are now untied the 

 fowl makes no endeavor to escape, but remains as 

 it were transfixed, and refuses to move even when 

 urged to do so. Preyer observes in passing that 

 the chalk-line constitutes no essential part of the 

 conditions, inasmuch as a fowl may be equally 

 well thrown into a state of hypnotism by simply 

 holding the animal for a short time upon the 

 ground so as forcibly to prevent struggling. 



After Kircher, no one seems to have investi- 

 gated the phenomena of hypnotism, or, as Prey- 

 er calls it, kataplexy, till the years 1872-'73, 

 when some articles on the subject were published 

 by Czermak. The most striking of his experi- 

 ments were those which he conducted on inver- 

 tebrated animals — crawfish, for instance, being 

 made to lie on their backs motionless, or even to 

 stand upright upon their heads. Czermak en- 

 deavored to account for the facts which he de- 

 scribed by supposing that in some way or other 



1 "Die Kataplexie und der thierische Hypnotis- 

 mus" (Gustav Fischer, Jena, 1878). 



a In a postscript Preyer states that he has found this 

 experiment to have been published ten years earlier, 

 by Daniel Schwenter, and the quotation which he 

 makes from Schwenter's book goes to prove that 

 Kircher probably derived his knowledge of the ex- 

 periment from that source. 



the act of fixing the eyes upon a certain object, 

 or of gazing into space, caused the animals to 

 become sleepy and stupefied. 1 So vague an ex- 

 planation could scarcely in any case be entitled 

 to rank as a physiological hypothesis, and Preyer 

 showed, in 1873, that the act of gazing had noth- 

 ing to do with inducing the state of kataplexy, 

 inasmuch as animals fell into exactly the same 

 state when their optic nerves were divided, or 

 their eyes covered with a hood — provided that 

 their bodies were at the same time held in some 

 unnatural position. Preyer therefore propounded 

 a theory of his own, which, as first published, was 

 that the state of fear into which the animal is 

 thrown by being held in some unusual attitude 

 serves to inhibit the power of volition and so of 

 spontaneity — the animal, therefore, when released 

 remaining statue-like in the position in which it 

 was placed. In order to sustain this theory, 

 Preyer pointed to other cases in which fear serves 

 to inhibit spontaneity — as, for instance, the mo- 

 tionless horror which some animals exhibit in the 

 presence of great danger, the fascination of birds 

 by snakes, etc. The theory as thus stated was 

 very justly criticised by Heubel, who, in 1876, 

 published a paper detailing his own researches 

 on the subject, and seeking to identify the state 

 of hypnotism with that of ordinary sleep. The 

 effect of this criticism was to make Preyer state 

 his theory with greater clearness, and, as we now 

 have it (1878), it seems to be as follows: Any 

 " sudden, strong, unexpected, and unusual stimu- 

 lation of centripetal nerves " produces an emo- 

 tion of fear, which in turn produces some inhibi- 



1 When we fix our eyes upon a certain object, and 

 then alter their adjustment for some more distant 

 point, so that the eyes endeavor, as it were, to look 

 through the object, there is no doubt that after a time 

 a somewhat sleepy feeliDg may be produced. Some 

 persons, I find, can perform this action more easily 

 than others, and it does not seem to consist altogether 

 in maladjustment. At least, I have observed t hat when 

 the action is performed by persons who can do it well 

 the pupils dilate prodigiously, and this even when the 

 eyes are fixed upon a bright light, such as the naked 

 flame of a moderator lamp. As the action is com- 

 pletely under the control of the will, one is thus able 

 to observe the curious spectacle of the inhibition by 

 the will of a reflex which under all other circumstances 

 is beyond the control of the will— the pupils dilating 

 or contracting instantly at word of command, and 

 quite irrespective of the stimulus supplied by light. 



