SOME PHYSIOLOGICAL ASPECTS OF HYPNOTISM. 523 



prominent owing to the cessation of the inhibitory in- 

 fluences. In popular language, the reins by means of which 

 inhibitory restraint was possible having been cut, the 

 influence of the whip has full play. In the case of the 

 somnambulist, the resultant augmentation of nervous centres 

 may be so pronounced as to outlast the state of hypnotic 

 unconsciousness and obvious will-paralysis, so that the 

 subject may show the increased susceptibility to respond to 

 sensory stimuli, even when other evidence of the actual 

 condition of hypnotisation has disappeared. The following 

 experimental data are illustrations of this feature. 



Acuteness of Hearing, as tested by Beaunis,^ was found 

 in several instances to be twice as great in the somnam- 

 bulistic stage and, in some cases, to remain greater after 

 recovery. The rapidity with which a prearranged move- 

 ment could be accomplished, in response to a definite 

 sensory stimulus, what is known as central reaction time, 

 was found to be accelerated from o'3 to o'2 of a second for 

 hearing and from o'ly sec. to o"i4 sec. for touch. 



I now pass to the final and most subtle aspect of hypnotic 

 phenomena, the part taken in the production of all these 

 phenomena by the train of mental changes known as sugges- 

 tion. This is in the main a subject which must be dealt 

 with on the psychological side, but its physiological aspects 

 may be conceived along the following lines. We are aware 

 that one idea suggests another and that volitional move- 

 ments are the outcome of such suggested ideation. The 

 physiological basis for this is decidedly obscure, but modern 

 neurology has comparatively recently brought into promin- 

 ence one feature which is pertinent to the present inquiry. 

 Functional activity is undoubtedly associated with structural 

 growth, functional inactivity with actual dwindling or 

 atrophy. It is only in the last few years that this has been 

 extended to the processes of the central nervous system. 

 The passage of nervous impulses across gaps is the 

 functional activity of the terminal nerve-hbre branches ; 

 if persistently repeated these branches may be conceived 

 as being brought into conditions favourable for their growth, 

 ^ Beaunis, Ze Soiiniatnlmlisme. 



