THE CHEMISTRY OF SLEEP. 237 



like slumber of the body while the mind remains awake. The 

 sleep from the action of excessive cold, which precedes death, is 

 due, of course, to general retardation of the circulation, which in 

 due time affects the brain, but probably has but a partial analogy 

 with natural sleep. It has not been sufficiently examined to de- 

 termine whether dreams accompany it at any stage. The de- 

 lusions from the abuse of opiates and those of delirium tremens 

 are of the class of waking dreams. Death by drowning is asserted 

 to be preceded by extraordinary waking dreams, sometimes rather 

 pleasurable than otherwise. 



The most important of all species of sleep for our present pur- 

 poses of comparison are those produced by anaesthetic agents. The 

 general use of these is now but about half a century old, though 

 it has been shown that the principle of anaesthesia and its use in 

 surgery, etc., is about as old as the Christian era. Dioscorides 

 describes the use of the mandragora root, steeped in wine, as an 

 anaesthetic drink to produce a sleep in which painless amputations 

 and other surgical operations could be effected, Pliny and Apu- 

 leius (author of the famous Golden Ass) each make similar state- 

 ments. Sir B. W. Richardson announced, in 1875, that he had 

 experimented with mandragora, and had largely confirmed the 

 ancient stories about it. The moderns have a great number of 

 anaesthetic agents, some of which are permanent gases, others 

 volatile liquids, which are mostly administered by inhalation; 

 but we yet know very little, in exact scientific detail, about most 

 of them. Some, when given in properly graduated doses, furnish 

 us with conditions approaching closely to those of natural sleep, 

 generally of a dreamless kind ; but others, if given in small doses, 

 furnish us examples of sleep of the will power and reasoning 

 functions, accompanied by emotional dreams and hallucinations. 

 In the case of nitrous oxide (laughing gas), especially when given 

 in moderate doses, mixed with air ox oxygen, emotional excite- 

 ments of the most remarkable kind result. The subject will often 

 fly into an energetic rage, manifesting a violent and ludicrous 

 pugnacity toward those about him. Others will declaim in an 

 oratorical manner, sometimes sensibly and coherently. Of such 

 occurrences the subject often retains vague memories, like those 

 of natural dreams. Thus memory persists during the action of 

 this agent, as in true sleep ; and, as in sleep, the will-control is 

 wanting. The natural instincts, no longer restrained, rise up and 

 assert themselves. " In vino Veritas." Ordinary alcoholic intoxi- 

 cation, indeed, is but one kind of anaesthesia, and passes in its 

 progress through the same characteristic stages or phases that 

 have been previously defined. 



The generalization remaining to be brought forward is as fol- 

 lows : It has already been indicated that of all the known arti- 



