4 BIOLOGY AND SOCIAL PROBLEMS 



personality is, strictly speaking, a property of 

 the nervous system and is in no true sense the 

 direct result of any other system of organs. 

 The nervous system, to be sure, is embedded 

 among other organs of the body, and the 

 environment thus provided influences pro- 

 foundly its condition and action; but what is 

 meant by individual personality, acuteness or 

 dullness of sense, quickness or slowness of 

 action, temperamental traits, such as a gloomy 

 or bright disposition, incapacity, shiftless- 

 ness, honesty, thrif tiness, or sweetness, are all, 

 strictly speaking, functions of the nervous 

 system. All these traits, then, that count for 

 so much in making the individual an effec- 

 tive or ineffective member of society, are the 

 direct product of his nervous system, a system 

 which is equaled in its importance in social 

 problems only by the reproductive system. 



How the nervous system subserves person- 

 ality, and how in man it has come to be the 

 seat of that general function, are questions 

 whose solutions are to be sought in the condi- 

 tions of our nervous organs to-day and in the 

 course which their evolution has taken. 



The body of man, like that of other higher 

 animals, is composed of an immense aggre- 



