THE NERVOUS SYSTEM ITS HIGHER WORK 257 



ferent side of nervous action. We have said that reflex 

 elements can be found in almost any elaborate movement. 

 In walking, for example, the assumption of a given 

 position by the body insures the return to the centers of 

 impulses which cause the next appropriate change. We 

 do not consciously resolve to take each step. The very 

 idea is painful. One step accomplished makes the taking 

 of another the natural sequel. Turning to our analogy, 

 we readily see that when the grand advance is under way 

 the continuance of the march will probably be intrusted 

 to the direction of lower officers. Difficulties encountered 

 they will report to the general if this seems necessary; 

 minor obstacles they will meet upon their own responsi- 

 bility. Thus when we walk we may be aware of gutters 

 to be crossed, but we do not notice at all the incessant 

 slight adjustments which are made for the lesser inequal- 

 ities of the path. 



The human brain contains at birth connections which 

 make possible the execution of a moderate number of 

 useful reflexes. Among these are sucking, winking, cough- 

 ing, sneezing, and vomiting. Of course, there are also the 

 requisite mechanisms for the government of breathing, 

 the circulation, and the digestive tract. Such a brain 

 appears to differ from that of one of the lower animals 

 chiefly in its capacity for continued development. Loeb 

 has shown that all that is acquired in the experiences which 

 come to the child may be covered by the term "associative 

 memory." The expression as used by him does not refer 

 to the power to review past experience as a conscious 

 process, but only to the power to acquire new reactions to 

 environmental conditions. An early gain in this direction 

 is the attainment of the ability to reach after and grasp an 

 object which has stimulated the visual department of the 

 nervous system. This seems to signify the opening of a 

 pathway in the brain from the region receiving impulses 

 from the retina to the region from which impulses go out to 

 the muscles controlling the hand. 



In similar fashion we can picture the acquirement of one 



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