522 SCIENCE PROGRESS. 



passage of impulses and the phenomena grouped under the 

 term fatigue. In man the strained and persistent gaze of 

 the subject may result in the production of such fatigue 

 changes in those nerv^e-endings gaps, the forcing of which 

 is a necessary concomitant of the mental mood of volitional 

 attention ; if these become paralysed the volitional power 

 will be in abeyance, and the sleep of Hypnotism ensues. In 

 animals a similar condition is brought about by the forced 

 inactivity and persistent state of constraint. It is this phase 

 of the physiological conditions which Preyer has laid stress 

 upon. The rationale of the changes as described above may 

 be considered fanciful by psychologists, but it appears, at 

 any rate, that the resultant effect on the remaining portions 

 of the nervous system is tolerably definite. The particular 

 co-ordination of nervous processes which underlie volition 

 have normally resulted in a varied discharge along nerve- 

 paths to lower centres playing- upon gaps, and on the 

 cessation or diminution of such discharoes, such reo-ions 

 are released from the inhibitory restraint thus imposed. 

 The other nervous centres are now in a condition to re- 

 spond with greater ease to the arrival of nervous impulses 

 started in peripheral sense organs ; in other words, the 

 gaps are capable of being forceci by inipulses which would 

 be inadequate were the voluntary power in full develop- 

 ment. Such appears to be the condition of the nervous 

 system in the somnambulistic state of hypnotisation with 

 its unconsciousness, will -paralysis, and yet augmented 

 capacity to respond to stimulation of the sense organs. 



I am inclined to believe that the increased activity of 

 all nervous processes, except those underlying volition, 

 may be attributed to the diminished resistance of what are 

 here termed the gaps. This itself may be produced, not 

 only by the cessation of the inhibitory influences just 

 described, but by the unrestrained and unmodified flow of 

 such impulses as, by their play, directly diminish the gap- 

 resistance, and thus augment the activity of lower centres. 

 The cataleptic reflexes obtained in the monkey, etc., after 

 removal of the cerebral hemispheres, are probably largely 

 due to the operation of this second factor, which becomes 



