558 POPULAR SCIENCE MONTHLY 



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SPECIAL BOOKS. 



In its multiplicity of anecdotes this study of sleep* resembles the early 

 works of Ribot, and the author chats about each in an equally charming 

 and irresponsible fashion. She is not chary, however, of generalizations, 

 and a very limited number of examples suffices for wide inductions. In the 

 regions of physiology and hygiene she gives a careful account of the phe- 

 nomena of sleep, supple meriting these with valuable suggestions of her 

 own. It is only when she enters upon the pathology and psychology of 

 her subject that she betrays herself as one of that school, mostly French 

 and Italian, which may be called the romancers of science. 



She laments that we understand so little about sleep, which absorbs one 

 third of our lives. The extensive bibliography added to each chapter would 

 seem to disprove a want of scientific attention. The circulation in the 

 brain during sleep has been observed in animals by substituting a watch 

 glass for a portion of the bone of the skull. Experiments have shown also 

 that a withdrawal of blood from the brain precedes sleep, and all condi- 

 tions tending to this result produce sleep. Heat or excessive cold, which 

 draws the blood to the skin, is followed by drowsiness, and this is likewise 

 the consequence of digestion which summons the blood to the large abdomi- 

 nal vessels. Debility and great loss of blood also cause cerebral anasinia 

 and somnolence. 



If it be inquired what is asleep within us, we find that it is only a part 

 of the brain. It is possible for all the organs of the body to be active dur- 

 ing sleep excepting partially the nervous system. The voluntary muscles 

 are awake, also the sensory nerves and the cerebral centers controlling 

 each. Only because the different nervous channels are sensitive is it pos- 

 sible to arouse a sleeping person. The author considers that the fact of 

 being able to awake at a given time proves that the attention and will pre- 

 serve their activity. After investigating the many hypotheses in regard to 

 the causation of sleep, the conclusion is reached that sleep is the resting 

 time of consciousness. 



The pathological modifications of sleep embrace weakened and excessive 

 activity. Complete insomnia is found only among the insane or extremely 

 anaemic. Intermittent sleep is injurious, since there is not time in the fugi- 

 tive rest obtained for adequate nutrition of the tissues, Partial insomnia 

 is met with in persons who are liable to a flow of blood to the brain and 

 those with unbalanced and irritable nervous systems. It is also the result 

 of mental overstrain or extreme physical fatigue. On the other hand, ex- 

 cessive sleep has its attendant evils — the gradual weakening of conscious- 

 ness and the mental faculties, and the production of serious physical disor- 

 ders. Among rarer forms of pathological sleep the author discusses nar- 

 colepsy, latah, hypnosis, and somnambulism. 



The hygiene of the subject brings up interesting questions. How much 

 time should be given to sleep ? What should be the light, temperature, and 

 ventilation of the bedroom ? Should habit control us ? It is contended 



* Sleep: Its Physiology, Pathology, Hygiene, and Psychology. By Marie de Manaceine. New 

 York: Imported by Charles Scribner's Sons. Pp. 341. Price, £1.25. 



