THE HUMAN PLANT 375 



The modifications wrought by the environ- 

 ment are matters of detail; the fundamentals 

 of heredity, built up by thousands of genera- 

 tions of past environments, are fixed beyond 

 immediate change. 



Nor can we doubt that the same thing is true 

 of the fundamental physical, mental, and moral 

 traits of the alien races that make up the great 

 army of immigrants that come to our ports in 

 such numbers as to make their migration, in all 

 probability, by far the largest and most rapid 

 migration of human races that ever took place 

 in the history of the world. 



The total number of immigrants that have 

 come to America since 1880 within the com- 

 pass, therefore, of a single generation is more 

 than twenty-three million. 



This is a number in excess of the total 

 population of America at any census prior 

 to 1850. 



Such an influx must of necessity change in 

 very large measure the aggregate heredity of 

 the population of America. Whatever the 

 American race was in the middle of the nine- 

 teenth century, it is something far different 

 to-day. That at least is axiomatic, regardless 

 of our estimate as to whether the change has 

 been an improvement or otherwise. 



