ANATOMY, PHYSIOLOGY, OF NERVOUS SYSTEM. 465 



right and left side are perfectly natural, but it can be easily 

 seen that coherent speech is a unity which could not easily 

 result from the actions of two separate sources or agencies. 



CONSCIOUSNESS. 



The question is repeatedly asked in what sense conscious- 

 ness is a physiological property. This whole point may 

 be dismissed as far as its physiology is concerned by the 

 statement that of its real nature we know scientifically ab- 

 solutely nothing. Held by some to be merely a high form 

 of mechanical or chemical changes in certain cells, the 

 phenomena of consciousness have been reduced to merely 

 physical phenomena and so robbed of what we know as their 

 free will . Such investigators to be consistent deny that there 

 is such a thing as free will, but that all the multiplied inter- 

 changes of sensation and volition are just so many neces- 

 sary causes and effects. On the other hand, other observers, 

 usually without much scientific training, at one blow divorce 

 consciousness from all forms of brain activity and hold it to 

 be perfectly aloof and independent from changes which 

 occur in nervous cells. To such individuals the brain is a 

 secondary organ and its function somewhat questionable. 

 Possibly the true ground lies somewhere between the two. 

 It is the simplest every-day observation that states of con- 

 sciousness are, so far as we know, indissolubly locked with 

 states of brain. On the other hand, it seems in violation of 

 all knowledge that consciousness is but a necessary physical 

 result from the clash of nervous molecules. From the 

 standpoint of physiology it is, however, well to remember 

 that with this question, interesting as it may seem, we have 

 in this field at present nothing to do. 



SLEEP. 



The lower centers of the brain, the mid-brain and spinal 

 cord, and of course the sympathetic system, are in con- 

 tinued physiological activity. At no time during the normal 

 existence of the individual are the physiological functions 



