196 HEREDITY IN RELATION TO EUGENICS 



tions five marriages of first cousins and two of second 

 cousins. In these marriages insanity (manic-depressive?) and 

 apoplexy were common. 



Passing south the peninsulas projecting into Chesapeake 

 Bay often offer extremely isolated situations. A physician 

 of one of the extreme points of Dorchester County, seven- 

 teen miles from the railroad, writes me that most of the 

 marriages of that locality — '4n fact I may say all, were 

 between relatives and usually of the same name, and with 

 the usual result, dwarfed stature or born crippled, blunted 

 intellect or born idiots." This statement seems to me 

 probably exaggerated — ^what is meant doubtless is that an 

 exceptional proportion were thus affected. 



Finally at Carteret County, North Carolina, we have 

 another example of peninsular conditions which have led 

 to an extreme frequency of consanguineous marriages. Per- 

 haps three-fourths of the inhabitants of the county bear one 

 of four names, and mental deficiency is found in many of 

 the children. 



There are other points on our coast which I have not had 

 time to inquire into. It is safe to assume that, in the absence 

 of peculiar, disturbing conditions, all small, inhabited is- 

 lands off the coast and most of the more isolated peninsulas 

 will show numerous consanguineous marriages and a large 

 proportion of some one of a variety of defects. You can 

 pick out such locaUties by looking on the map. 



b. Barrier of Topography. — A most important barrier 

 is a height of land. How important it is is clear to 

 anyone who has lived in a valley and noted the free- 

 dom with which movements of the population take place 

 along the valley as contrasted with movements up the 

 hills to an elevation of even 200 to 500 feet. The valley 

 forms a social center and acquaintances are made and 

 marriages arranged there. Hemmed in by the barriers 



