470 WILLIAM WASHINGTON GRAVES 



Explanation of tables 1 and 2 



These tabulations represent 42,413 white persons. They show the results of scapular 

 classification derived by applying "The Age-Incidence Principle" to so-called "normal" 

 and to known to be sick groups in several age periods. Table 1, "normal" groups in age 

 periods 3 mos.-80+ years: in table 2, "normal" groups 6-40 years, and "sick" groups 

 5-44 years are shown. It will be noted that the results of classification are tabulated 

 in 5 "sick" groups, viz., Tuberculous, 1, 2, 3, 4, 5 and 6; Feeble-minded, 7 and 8; Prison, 

 9, 11 and 12; Sex-delinquent females, 10 and 15 and Insane, 13 and 14. On comparing 

 the percentages of convex types in these groups with the "normal" groups, in similar age 

 periods, it will be noted that there are approximately from If to 2\ times as many convex 

 types in the "normal" as in the "sick" groups. 



The results of investigations are queried in Groups 1, 2, 3 and 4, Table 1 and in Groups 

 A, 13 and 15, Table 2, because classification in these groups was made prior to the devel- 

 opment of dependable methods. Moreover, mixed scaphoid types (Cv + St, St + Cc 

 and Cv + Cc) were not noted by examiners of Groups 2 and 3, Table 1. "Normal" 

 Group 9, Table 1 and "normal" Groups A, B, D, F, G and O and sick Groups 1, 13 and 

 15, Table 2 are queried, because of the disturbed type ratios. Regardless of the error in 

 classification in Tables 1 and 2, the age incidence is clearly demonstrated even in all 

 groups showing 2 or more successive age periods. Mixed scaphoid types in the columns 

 headed: Cv + St, St -f- Cc and Cv + Cc in Groups 1, 4, 5 and 15, Table 1 and in Groups 

 A, B, C, D, E, 13, 14 and 15, Table 2 were apportioned among, and combined with, the 

 pure types (Cv + Cv, St + St, Cc + Cc) as suggested in reference numbers 9 and 10). 

 While recent personal investigations on material of known age show that mixed 

 scaphoid types (Cv + St, St + Cc and Cv -f- Cc), like pure scaphoid types 

 (St -f- St and Cc -f- Cc), decrease in frequence in successive age periods, it is, neverthe- 

 less, here suggested that in all future work pure and mixed scaphoid types be tabulated 

 separately, as for example in Groups 6 and 18, table 1, for the reason that many more 

 data on mixed scaphoid types are desired. Moreover, regardless of the nature of the 

 material (excellently, well or poorly adaptable) when adequate numbers are examined, 

 the variable ratios of scapular types become dependable controls of accuracy in classi- 

 fication. If classification be reasonably accurate, one seldom, if ever, finds as many 

 Cc + Cc as St + St; never as many St -+- Cc as Cv + St and never as many Cv + Cc 

 as St + Cc types. Finding such disturbance in the ratios, as in some of the groups 

 queried, serves as a reliable control on one's accuracy in classification, and I have used 

 this check in querying the accuracy in classification in some of the groups in tables 1 and 

 2. To determine the relative fitness values of one group in comparison with another in 

 similar age periods, when classification has been reasonably accurate in both groups, it 

 is only necessary to know the percentages of convex types in both groups. That group 

 which shows the largest percentage of convex types has the highest fitness value, as meas- 

 ured by scapular classification. 



Crum (45), Pearl (46) and others in studying the possible relation of heredity 

 to longevity in man and the investigations of Hyde (47) and of Pearl (48) 

 (49) and others in Drosophila, have demonstrated beyond question a definite 

 relation of heredity to longevity. 

 By the application of the age-incidence principle to statistical studies of 



