ANATOMY, PHYSIOLOGY, OF NERVOUS SYSTEM. 467 



impulses, and so produce sleep, and that waking would 

 consist in the moving together of these dendrons and so 

 re-establishing the natural flow of impulses. 



During sleep the entire range of conscious centers may 

 not be affected. Sometimes certain centers or portions of 

 certain centers seem to remain awake, and then these cen- 

 ters, relieved from the controlling influences of neighboring 

 centers run riot and give rise to the production of dreams. 

 When the centers so awake happen to be motor centers 

 there may be produced forms of sleep in which more or less 

 extended movements occur familiar to us under the name of 

 somnambulism . 



That sleep is not due to the lack of blood in the brain, 

 and so be a phenomenon like fainting, is easily disproved 

 by experiments which show that the blood supply in the 

 brain while asleep sinks very little below the normal. 



HYPNOTIC PHENOMENA. 



Hypnotism is by many looked upon as an abnormal 

 variety of somnambulism. There is, however, connected 

 with this subject of hypnotism so much that is questionable 

 and suspicious along with the little that is real and scientific, 

 that it is exceedingly difficult to come to definite scientific 

 conclusions. It is explained by some as a peculiar sleep, 

 and looked upon by others as a mere form of embarrassment 

 and frightened imagination. 



TIME RELATIONS IN PSYCHIC PHENOMENA. 



That mental processes take a certain amount of time is 

 an e very-day observation. The exact measurement of simple 

 and definite psychical acts was first made as a result of the 

 observation that astronomers of equal care and precision 

 did not record the passage of a star across the hairs of 

 their observing telescopes at the same instant. This differ- 

 ence in time was at first attributed to a greater or less care- 

 lessness in the observer. Repeated experiments soon showed 

 that there was a difference in time even when both observers 



