THE HUMAN PLANT 367 



This extreme example will serve to suggest the 

 extent to which the individual even of the very 

 best heredity is dependent upon environment for 

 the bringing out of his inherent potentialities. 



As another extreme example might be cited 

 the case of the child who becomes blind and deaf 

 in infancy through some accident or disease. 

 Exceptional cases like those of Laura Bridg- 

 man and Miss Helen Keller, in which, through 

 infinite effort, the other senses are made in part 

 to compensate for the loss of sight and hearing, 

 building up the brain through vicarious channels, 

 serve to give further emphasis to the fact under 

 consideration the all-importance of the environ- 

 ing influences that we commonly speak of as 

 "educational" in completing the work which 

 heredity carries only to the nascent state of 

 development. 



THE COMBINATION OF RACES 



Yet another respect in which the problems of 

 producing a better human race in our day run 

 parallel to the problems of the plant developer is 

 with reference to the foreign materials that make 

 up the stock for the propagation of future 

 generations. 



It is easy to draw the inference from the r 

 casual glimpses into the past history of our race 



