RESEARCHES INTO ANTHROPOLOGICAL HEREDITY 



199 



Any individual with an index higher or lower than those here 

 mentioned must be considered either a + variant or a — variant, 

 whose offspring, as a matter of course, would revert to the average 

 index of the type. But that this is not the case becomes very soon 

 apparent when the anthropological data collected in the two districts 

 are considered. It is then seen very plainly that there are at least two 

 types in each of the districts. One is common to both districts. It 

 is the northern fair nucleus, which in Selbu amounts to 78 % of the 

 population, in Tj^dalen to about 66 %. The index of this nucleus is 

 about 77,5. Beside this fair nucleus there is found in Selbu a dark 

 brachycephalic type with the index about 83. 



A brachycephalic type is also found in Tydalen but only in a small 

 proportion. There is also found a dark dolichocephalic type with 

 an index about 73. Anthropologically it is, however, difficult to cal- 

 culate the exact cephalindices of these types, but the data point in 

 the direction mentioned. 



TABLE 1. 

 Index cephaliciis in adult man and woman in Selbu and Tydalen. 



Index ceph. 



64 65 



6667 



68 69 70 71 



72 73 



741757677 



78179 



8081 



82 



83 84 85 86 



87 



88 



89 



Selbu 



cf ... 



Tydalen s 



^ 19 ... 



1 

 1 

 2 2 



— 2 



31 5 

 61 



2 4 



10 



8:i3 



14|l5 

 811 



QlSll 



14 10 1Ö 



3' 9 7 



S' 5 4 



9,11 



2 — 



G 



5-3 



1 3 41 7,11 19 



21 



31 



40|47t34|37|37,25 20|l4| 2 



- 21 



Before entering upon the subject itself I had to ascertain to what 

 a degree index cephalicus changes with years, and to what a degree 

 it differs in the two sexes. It did not seem impossible that a low 

 index in childhood might develop into a high index in the grown up 

 • individual, or the reverse. I have settled the question by measuring 

 children of all ages and from both districts. It appears from this study 

 that index cephalicus passes through only small changes during 

 growth. In children from the age of 5 till the age of 10 the index 

 is 1 à 1 ^/a higher than in grown up people. It decreases regularly 

 from the age of 5 till it is stabilized at the age of 16. 



Although it does not complicate the subject in any degree worth 

 mentioning it has, of course, to be taken into consideration. 



In grown up women in Selbu I found that index cephalicus was 



Heredilas I. 14 



