390 MAURY ON SLEEP AND DREAMS. 



force and persistency ol natural functions. This topic 

 has hardly yet received all the attention it deserves as 

 a branch of animal physiology. It might merit a trea- 

 tise in itself. 



We have hitherto been speaking chiefly of what 

 may be considered as the natural form of sleep. But. 

 there are many anomalous aspects of this great function 

 which we are equally bound to notice some of them 

 depending on casual and not always obvious causes 

 others on artificial means used to produce sleep or 

 those states akin to it in which there is a suspended 

 action, more or less, of the senses connecting us with 

 the outer world. Some of these states, which may well 

 be called waking dreams, are of deep interest in the 

 mental and moral, as well as physical relations they 

 disclose to us ; involving the intellectual faculties, and 

 even the emotions, as well as the simple functions of 

 the senses. 



Somnambulism, though we may class it among the 

 anomalous aspects of sleep, is probably not more than 

 an exaggerated form of phenomena of ordinary occur- 

 rence. The retention of a certain voluntary power, 

 while the senses are more or less wrapt up in slumber, 

 and this unequal slumber of the senses themselves, are 

 well known to us in the common case of talking in 

 sleep, and other bodily motions associated with dreams. 

 Somnambulism is doubtless always thus associated. 

 Why in certain persons this connexion is so strikingly 

 attested it would be hard to say ; but still it is only a 

 gradation of state, and not a detached phenomenon. 



