OF A CERTAIN PENNSYLVANIA FAMILY. 



89 



Table 5. 



'Still reproducing. 



4. Comparative Survival. 



The increase in the defective classes due to their high fecundity is 

 generally counterbalanced, it is said, by the relatively high infant and 

 child mortality of this class. The analysis of our data lends some sup- 

 port to this view. The proportion of those surviving to the age of 20 

 in each generation was determined for the Lines A, C, D, E. This 

 was done by calculating the average number surviving and dividing 

 this by the average number born for the same generation and line. 

 Table 6 gives the corresponding survivals for the average number of 

 births shown in table 5 while table 7 gives a comparison of survival 

 ratios obtained in each case. 



The survival ratios for successive generations increase in the socially 

 efficient Lines A, C, while they show marked decrease in the defective 

 Lines D, E. The small survival ratio of the defective lines taken in 

 conjunction with the low birth-rate is illustrative of Nature's method 

 of eliminating the unfit. Since these communities lack many of the 

 agencies which nowadays bolster up the inadequate, it is probable 

 that this method is in more effective operation here than among the 

 defective and delinquent classes of other social groups. 



5. Differential Migration. 



The behavior of the five lines of the Rufer network with regard to 

 their migration to another section of the State or country may next 

 be considered. Taking A, B, C together, that is, the lines which show 

 a decreasing proportion of socially unfit, we find only 3 of the whole 

 number at the original place of settlement of the family ; 42 are settled 

 within a radius of 15 miles of this place, while the remainder, numbering 

 nearly 200, are widely scattered, many having migrated as far as North 

 Dakota, Idaho, Alberta, and California. 



Turning now to D, E, those lines showing an increasing proportion 

 of the socially inadequate, we find that exactly the opposite is taking 



