182 HEREDITY IN RELATION TO EUGENICS 



multiply itself into many individuals either all of one sex 

 or of both sexes, as the ease may be; and these individuals, 

 moving apart, would form new prohferating centres. In 

 the multipUcation of negative and positive traits we would 

 see this plain difference — that negative traits multiply most 

 in long established and stable communities where much 

 inbreeding occurs, while positive traits are increased by 

 emigration, as a fire is spread by the wind that scatters fire- 

 brands. If, on the other hand, the negative traits be scat- 

 tered the chance of mating with the same defect is diminished 

 and the trait is not reproduced. Conversely, a country 

 characterized by much inbreeding will have a population 

 that is affected prevailingly by negative traits with a slight 

 tendency for positive traits to increase; while a country that 

 is settled by a restless people will show a small percentage 

 of negative traits and a high percentage of positive ones. 



That the picture of the dissemination of traits that I 

 have drawn is not exaggerated but corresponds to the em- 

 pirical facts is proved by the evidence of many studies. 

 Thus Alexander Graham Bell (1889) finds that not only 

 the deaf mutes of Martha's Vineyard but ''groups of deaf 

 mutes who have never been near Martha's Vineyard, trace 

 up to " the blood of James Skiff. A genealogist with un- 

 usual inteUigence and breadth of interest has traced a 

 "bleeding" tendency from a Hannant who came from 

 Norfolk, England, and whose progeny settled in Sullivan 

 County, Pennsylvania, and created there a colony of 

 bleeders; and by emigration has started new colonies in 

 Minnesota, South Dakota, and California. Students of 

 Huntington's chorea find many of their widely scattered 

 cases tracing back through Delaware County, New York, 

 to the sources of its early population at East Hampton, 

 Long Island, or to that sister settlement of the New Haven 

 Colony, Fairfield County, Connecticut. Even students of 



