98 WONDERS OF ORGANIC LIFE. 



lectual faculties and voluntary movements ; 

 ■while the organic processes (namely, the action 

 of the heart, digestion, the peristaltic action of 

 the abdominal viscera, and various secretions) 

 continue. Nevertheless, although the above 

 may be taken as a general definition of sleep, 

 it is not strictly accurate ; for in some persons, 

 during health, and in most, during any trifling 

 or more serious disturbance of the system, the 

 mind will be occupied in dreams, in which a 

 long train of occurrences seem to take place, 

 varied according to some previous mental im- 

 pression, the condition of the nerves, the state 

 of the stomach, or the nature of the transactions 

 in which the person dreaming has actually been 

 engaged. In these dreams, we walk, we run, 

 we ride, we converse, we sing or listen to music, 

 we engage in conflicts, or are in dread of danger. 

 Often these dreams, the acting out of which 

 appears to be so long, are but momentary, and 

 produced by some impulse upon one or more 

 of the organs of the senses ; for not unfrequently 

 real sensations are felt during sleep which do 

 not awaken the sleeper, but give rise to a dream, 

 in which he is either a visionary sufferer or 

 actor. A sudden sound, as we have experi- 

 enced, maybe the cause of a dream, the conclu- 

 sion of which is wound up by an imaginary 

 clap of thunder, or the firing of cannon. Pain 

 suffered during sleep, yet not to such a de- 

 gree as to rouse the patient, will throw the 

 sleeper into an imaginary position, giving him 

 a false reason for the sensation endured. Dr. 



