434 HEREDITY AND ENVIRONMENT 



of a great world movement and we cannot re- 

 verse the current, but we may to a certain ex- 

 tent direct that current into the more desirable 

 channels. 



There is a popular belief that hybrid races 

 are always inferior to pure bred ones, but this 

 is by no means the case. Some hybrids are 

 undoubtedly inferior to either of the parents 

 ' but on the other hand some are vastly supe- 

 rior; only experience can determine whether 

 a certain cross will yield inferior or superior 

 types. Society may well attempt to prevent 

 those crosses which produce inferior stock 

 while encouraging those which produce su- 

 perior types. 



It is race mixture which makes the problem 

 of immigration so serious. Generally immigra- 

 tion is regarded merely as an economic and 

 political problem, but these aspects of it are 

 temporary and insignificant as compared with 

 its biological consequences. In welcoming the 

 immigrant to our shores we not only share with 

 him our country but we take him into our 

 families and give to him our children or our 

 children's children in marriage. Whatever the 



