Raymond Pearl 27 
TABLE IV. 
Probable Brain- 
weight of a group 
of Hessians of 
the same sex, 
age and stature 
as the 
Mean Brain- 
weight 
obsei'ved 
(Bavarian or 
Bohemian) 
Difference 
expressed as 
in excess or 
defect of 
Hessian 
values 
Difference 
as per cent, 
of observed 
mean 
(Bavarian or 
Bohemian) 
Equation 
on which 
Hessian 
estimate is 
based 
Bavarian (J ^, Total 
? ? , Total 
„ S 6, Young 
??, Young 
Bohemian ^ ^ , Total 
??, Total 
„ S 6, Young 
„ ? ?, Young 
1388-984 
1265-137 
1397-157* 
1277- 317* 
1394-570 + 
1259-310 + 
1399-5271 
1278- 935j 
1363-185 
1220-356 
1369-110 
1235-504 
1454-839 
1310-914 
1460-150 
1313-910 
-25-799 
-44-781 
-28-047 
-41-813 
+ 60-269 
+ 51-604 
+ 60-623 
+ 34-975 
-1-9 7. 
-3-7 % 
-2-0 7 
-3-4 7„ 
+ 4-1 7„ 
+ 3-9 7„ 
+ 4-2 7„ 
+ 2-7 7„ 
No. 23, p. 63 
)) 25, „ 
» 24, „ 
„ 26, „ 
23, „ 
)) 25, ,, 
„ 24, „ 
„ 26, „ 
This table brings out several points of considerable interest. In the first 
instance is to be noted the general effect of reducing the Hessians to the same 
" stature-age base " as the other races, upon the interracial differences in mean 
brain-weight. In the case of the Bavarians the deviations from the Hessian 
means are reduced slightly in both male series, and the "young " female series, 
when stature and age differences are eliminated. In the " total " female series the 
difference is increased over the original gross difference. The explanation for this 
discrepancy in the female " total " series is to be found in a peculiar abnormality 
which this series shows in its elemental frequency distribution, and which will be 
discussed later (p. 40). In the case of the Bohemians we get the somewhat remark- 
able result that a reduction to a common " stature-age base " actually increases 
the differences of this racial group in brain-weight as compared with the Hessians. 
Or in other words, in the samples with which we are dealing the stature and age 
differences act in a compensatory way and bring the mean brain-weights closer 
together than they would be if we dealt with selected samples of the populations, 
each sample having the same mean age and stature. The fact already noted 
(p. 18) that the mean brain-weights deduced from Matiegka's tables for the 
Bohemians are somewhat too large, may now be examined in detail. This 
Bohemian material was published by Matiegka in the form of correlation tables 
with unduly large units of grouping (cf Tables 25 to 28, Appendix). The base 
unit for brain-weight was 100 gr. Now in calculating the general population 
mean from these tables one assumes that the individuals in each elemental 
frequency group centre in brain-weight at the mid-point of that group. Thus, the 
individuals recorded as having a brain-weight of between 1300 and 1400 grams 
are assumed to centre at 1350 gr. But evidently this assumption will not be true 
except at the middle of the whole range. For example, the brain-weights recorded 
* This assumes that the mean stature of the Bavarians would be the same in the " young " group as 
it is in the " total " group. The error introduced by this procedure is practically negligible. 
+ Here again, on account of lack of data, the mean stature is assumed to be the same in "total" 
and "young " groups. 
t See footnote on p. 24. 
4—2 
