% 
504 FRETS, THE. INDEX CEPHALICUS. 
material must be diminished with 2 or 3 units (p. 492), it appears 
that the index of the Swedish material is about one unit lower 
than that of the Dutch (p 017). 
To get an insight into the movement of growth of the head it 
is necessary to observe children several years consecutively. The 
data that I have gathered on this subject are laid down in table 
10 (p. 500-3). From the 82 boys of tab. 10 that | have measured with 
about one year interval I have calculated the mean index of the 
two successive ages!) I found M; = 81.23 and Mo = 81.14. For 
53 girls I found M; = 81.06 and M: = 80.76. Of boys as well as 
of girls the index has gone back a little in the course of about one 
year. Calculating from this material of children (tab. 10) the mean 
growth pro year for succeeding ages, I find a rather regular movement 
of growth. If the material were larger it would be possible to decide 
in this way, if there are periods of stronger growth. (Kaup, 1922). 
Tab. 11 (p.505) gives the indices of some families of which I 
took three measurements in about 3 years. Remarkable is fam. 3d of 
14 children of 13—0.5 years. We see from it that there are in this 
family little plus differences as well as little minus differences 
(f.i. plus differences of the 9th and the 10th child with indices of 
84 and 85). The mean index of the first measurements of these 14 
children is 81.86 and of the 3rd measurements 81.99. With young 
children irregularities are sometimes found. So in fam. 34c a 
child of 4 months has an index 85.2; at the age of one year the 
index is 81.5 and at the age of 3 years 79.3. A brother of this child 
had at the age of 4 months an index of 85 and now 2 years of 
age it has an index of 88. We have to do here with modifications 
at early ages (WaLCHER). These children are very weak, had 
rachitis. I suppose that the first of these children has got succes- 
sively the index that belongs to it according to its hereditary 
constitution. 
From our inquiry of the headindex of children we may conclude. 
that the index changes little during the growth. The index of adult 
men and women is a little lower than that of boys and of girls. The 
index of a number of boys and of girls at different ages was also 
with a second measurement slightly lower than a year before. 

1) The boys and girls of tab. 10 and 11 that I measured twice or thrice 
are of course only once inserted in tab. 13 and 14. 

