156 BIOLOGY: GENERAL AND MEDICAL 



foundation as the thought. Each is a cell memory. A 

 cell or group or cells, having been once impressed, recalls 

 the same impression and passes it around in the same 

 manner, producing definite impressions upon group after 

 group. The act of walking is not simple; the move- 

 ments of the limbs in balancing the heavy body as its 

 centre of gravity is alternately disturbed and recovered, 

 is extremely complicated, and necessitates the combined 

 efforts of many muscles brought into action singly or in 

 combination in orderly sequence. Yet this can be 

 achieved without conscious thought, because through 

 long practice the cells remember the lessons they have 

 learned and carry them through without a mistake. 

 How complicated is the performance of a fine pianist! 

 Does he know each note struck? Not at all; the whole 

 is a series of wonderfully well-coordinated, highly com- 

 plex, automatic acts resulting from the precise activity of 

 well-trained nerve cells whose memories do not fail. 

 How difficult to learn the piano where the eye reading 

 the notes and signs and the fingers interpreting them 

 must work in harmony! With what tears and pains 

 does the child learn to drum some simple composition! 



Thus, a consideration of the functions of the nervous 

 system inevitably brings us to psychology, and we are 

 tempted to inquire whether there is any essential differ- 

 ence between such motor automatism with its coordi- 

 nated movements and the psychic movements we know 

 as thoughts. The answer should be no. There are no 

 differences other than may be accounted for by the 

 materials and the mechanism. Thought seems to be a 

 succession of nerve transmissions following one another 

 in endless number and in orderly sequence, having their 

 source in an external impression. Once set in motion, 

 the stimulus passes on and on, the memory of each cell 

 reviving some other related memory in another cell. 

 Experience shows that these memories arise simulta- 

 neously in many cells, though the more lively are usually 

 developed to the exclusion of the others. Each thought 



