CHAPTER XVII. 



MENTAL AND PHYSICAL RESULTS. 



SECONDARY SEXUAL CHARACTERS AND INTELLIGENCE. 



There is a general impression that each individual starts out 

 in life destined to follow a prescribed path in its development, and 

 that this path is practically identical with that followed by its 

 parents. Because the son of a beardless youth in due time develops 

 a beard of his own, it is assumed that this same son should also 

 develop the same mental powers and characteristics which his father 

 developed, and at the same periods of his life. 



There are in this assumption two sources of error; first, it pre- 

 sumes a relationship between a functionless organ and the func- 

 tional condition of a very different organ ; and second, it presumes 

 that because the son of a beardless youth produces a beard of his 

 own, hence, a successive series of sons of beardless youths will 

 continue to produce beards to the same extent that sons of bearded 

 men would. 



Functional power, in the brain or in any other functioning 

 organ, is a condition into which the organ is placed as the result 

 of long continued use. In youth this functional power is at a low 

 stage because the greater portion of the energy of growth is con- 

 sumed in adding bulk and little can be spared for placing the in- 

 creased material into a functional condition. 



ORGANS DURING EMBRYONIC STAGE. 



The cells from which a new being grows are built up of mate- 

 rial having the functional condition of the parents at the time of 



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