418 HEREDITY AND ENVIRONMENT 



Whether we want it or not hybridization of 

 human races is going on and will increase. 

 Partition walls between classes and races are 

 being broken down; complete isolation is no 

 longer possible, and a gradual intermixture of 

 human races is inevitable. We are in the grip 

 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 this fact which makes the problem of 

 immigration so serious. In general immigra- 

 tion is regarded merely as an economic and 

 political problem, but these aspects of it are 



