1 64 SCIENCE FROM AN EASY CHAIR 



straint and works incessantly like an independent existence. 

 The disturbance of the nervous system set up by irritation 

 of the digestive organs, whether accompanied by pain or 

 not, is an independent cause of sleeplessness which often 

 co-operates with the first, and is (through the mechanism 

 of the nerves) often set going (though it may arise inde- 

 pendently) by an unhealthy excess in the excitement of 

 the brain's activity. There is no panacea for sleepless- 

 ness; the only thing to do is to consult a first-rate 

 physician, and strictly follow his advice. 



There are many irregularities and abnormal mani- 

 festations of sleep. There is the sleep which is induced 

 by drugs such as opium, chloral, and alcohol, and that 

 induced by chloroform, ether, and nitric gas. There is 

 the heavy sleep accompanied by stertorous breathing, 

 and there is the unconscious condition called "coma." 

 Then there is the prolonged sleeping called " trance," of 

 which that of the Sleeping Beauty, only to be broken by 

 a kiss, is an example. It is not possible, in the present 

 state of knowledge, to give an adequate account and 

 explanation of the condition of the brain in these different 

 forms of sleep, nor of the causes which induce that 

 condition. One of the most interesting forms of sleep is 

 the condition called " somnambulism," or sleep-walking, 

 in which part only of the brain is asleep, and other parts 

 connected with various degrees of mental activity are in 

 waking order. Sleep-walking is a condition which occurs 

 spontaneously. On the other hand, " hypnotism " is the 

 name for a peculiar kind of sleep produced intentionally 

 by an operator on a patient by certain treatment and 

 direction. In one of the stages of artificially induced hyp- 

 notic or " mesmeric " sleep called the somnambulic stage 

 only so much of the brain is asleep as is concerned 

 with conscious memory. The brain receives stimulation 

 through the sense-organs, and the patient has the eyes 



