86 HEREDITY AND SOCIAL FITNESS 



XIV. STATISTICS. 

 1. The Population Considered. 



The total number of individuals considered in the investigation is 

 1,822. The number appearing on the two charts and including the 

 direct descendants of the Rufers and Riels, their consorts, and in a few 

 cases the product of other matings of these consorts, is 912. The 

 remainder, numbering 910, have been studied in connection with the 

 strains into which out-marriages have occurred. 



2. Comparative Efficiency of the Several Lines. 



In the foregoing description we have dwelt on differences in the 

 social efficiency of the several lines. These differences may be sum- 

 marized in the following manner: Confining our attention to the direct 

 lines of descent, we have tabulated, first, the proportion of the socially 

 fit to the socially unfit in successive generations. These classes are 

 necessarily only roughly delimited, regard having been paid to the 

 totality of the relationships sustained by the individual to his family 

 and the community at large. If it is known that he received occasional 

 help from relatives, but in general was able to "pull his own weight," 

 he is classed with the socially fit. If he was often the recipient of 

 public or private aid for the care of himself or his family, or if he was 

 clearly an institutional case but held his place in the family and the 

 community through the forbearance of relatives and friends, he is 

 classed with the socially unfit. The classes also exclude those who 

 died before their mental condition could be determined or who are 

 still too young for determination. 



Figure 1 shows the proportion of socially fit to the socially unfit of 

 successive generations in the five lines of the Rufer network. The 

 proportion of the socially fit is represented by the part of the square 

 left blank; the unfit by the heavily shaded portion. It has been 

 thought best, in several instances where the individual was on the 

 border-line of efficiency, to make a third class represented by the 

 lightly shaded areas. 



This scheme illustrates strikingly the concentration of social effi- 

 ciency in Lines A, B, and C, while the inefficiency has concentrated in 

 Lines D and E. Furthermore, the small proportion of the socially 

 inefficient suffers a decrease in the three superior Lines. In Line A 

 it is 2 to 15 in the third generation, as against 1 to 38 in the fourth, and 

 2 to 61 in the fifth generation. It is interesting to note that this slight 

 persistence of defect is due to the marriage of one defective in genera- 

 tion 4 to a defective member of Line D. 



In Line B, members of all generations following the first are socially 

 fit, while in Line C there are in the third generation 14 socially fit 



