EVOLUTION OF NERVOUS SYSTEM 99 



reformer. Thus the hormones, to return to our original thesis, 

 illustrate how profoundly the nervous system is under the in- 

 fluence of its immediate organic environment. 



THE NERVOUS SYSTEM AND ORGANIZATION 



If, now, we picture to ourselves the evolution of the nervous 

 system of man, we must imagine the formation of the chemi- 

 cal elements from the electrons of the stellar laboratories, the 

 combination of certain of these elements into organic aggre- 

 gates and the formation of unicellular organisms, the develop- 

 ment of multicellular types in whose organization muscles ap- 

 pear, then receptors, and finally adjusters or central nervous 

 organs culminating in the brain of man. 



Such a series forms, superficially, a seemingly natural and 

 smooth sequence and yet when it is examined closely, it proves 

 to be a succession of breaks and contradictions. The carbon, 

 hydrogen, oxygen, nitrogen, and other elements of our bodies 

 act in a radically different way in the hands of the chemist 

 from what they do as an organized part of our nervous proto- 

 plasm. The invariable nature of the chemical reaction is in 

 strong contrast with the fluctuating uncertainty of volitional 

 activity. True, on repeating what are intended to be exactly 

 the same processes, the chemist never gets exactly the same 

 results, but he knows that the slight differences he meets with in 

 his work are errors of manipulation and observation and not 

 evidences of wilfulness or disobedience on the part of the 

 material he deals with. Yet the activities of these same chemi- 

 cal elements when organized into the children of his family 

 are regarded in a very different light and under the head of 

 personality he subjects them to censure and approval with the 

 view of lasting change and improvement. How profoundly 

 different is the conception of the activities of the isolated ele- 

 ments of our bodies and of these same elements organized into 



