294 Heredity and Eugenics 



warning that a defect is in the blood of some of the strains 

 that in time will affect the entire sect who remain in that 

 part of the country. 



MIGRATIONS AND THEIR EUGENIC SIGNIFICANCE 



The human species has come to occupy the entire 

 habitable globe. This fact is mute testimony of man's 

 migratory capacity and tendencies. Just as the Norwegian 

 lemming has been observed, in consequence of several 

 years of favorable conditions for breeding in its mountain 

 home, to spread over the surrounding territory in great 

 bands, seeking less crowded breeding grounds; even as the 

 army worm and the grasshopper swarm from their native 

 territory; so man, also, under the pressure of crowded 

 conditions, poverty, and oppression, or lured by brighter 

 prospects elsewhere, may move in hordes to other lands 

 that seem to offer better opportunities. Thus Asia seems 

 to have debouched her surplus population upon Europe 

 in the shape of the Huns during the fourth and fifth cen- 

 turies of our era and the Turks during the fourteenth and 

 fifteenth centuries. So the Anglo-Saxons and the Normans 

 successively swarmed upon England. So, among savages, 

 the Masai of Africa moved upon the neighboring tribes and 

 established themselves over much of southeastern Africa. 

 So in the last three centuries the Americas and Australia 

 have witnessed the greatest migrations that the world has 

 ever seen, hundreds of thousands annually coming from 

 overcrowded Europe, and Asia to the "New World." 



For us in America the phenomena of migration should 

 have a special interest. Excepting for the few scores of 

 thousands of Indians there was a continent devoid of a 

 population — a clean slate upon which history was to be 



