BASIS OF INVESTIGATION. 



no appearance of use-inheritance applied to brain power unless the 

 parent has lived many years before reproducing. 



The dependence and relationship of acquired functional capac- 

 ity of the brain upon time is recognized and may be illustrated in 

 many ways. In common law the individual is not supposed to know 

 enough to take care of himself before twenty-one. The Consti- 

 tution of the United States says he is not eligible to become a Rep- 



*s* 



SL3 , i, J* 



AGES. W 4.X <W *& <* 3 j*> 



PIG. 2. GALTON'S DIAGRAM (EXPANDED) OF BRAIN GROWTH. 



resentative before twenty-five, is not competent to be a Senator until 

 thirty, and not wise enough to be President until thirty-five. 



HYPOTHETICAL COMMUNITY. 



Let us assume a mining camp with one hundred men whose ages 

 vary from twenty to thirty, the majority of whom have more than 

 ordinary native intelligence, and many of whom have had the bene- 

 fits of a college education; let us assume, also, that there comes to 

 this community a man of fair intelligence, who is fifty years of age, 

 who had in his youth only limited opportunities for education, but 

 who has had a wide experience in many parts of the world under 



