Raymond Pearl T6 
TABLE XVIII. 
Variation in the Weight of the Cerehrum. English Males. 
Boyd-Marshall Data. 
Character 
Mean 
S. D. 
C. of V. 
No. 
Table 
Weight of cerebrum 
Stature 
Age 
308 
308 
308 
1184-940 -l-4-8.'39gr. 
171-602+ -268 cm. 
49-481+ -645 yr. 
45 
45 
46 
126-438 + 3-436 gr. 
6-976+ •190 cm. 
16-770+ -456 yr. 
10-670+ -293 
4-065 ± -111 
For the correlation of weight of cerebrum with age I find from Table 46 
r = - -1412 ± 0377, 
and for the correlation of the weight of cerebrum with stature from Table 45 
?■ = -1202 ±-0379. 
These values bring out the following points. The cerebral hemispheres are 
markedly more variable in weight as judged by the coefficient of variation than 
is the entire encephalon. This greater variation may denote a really greater 
variability of this part of the brain, or it may be due to the variable element 
which enters as a result of the separating of these organs from the rest of the 
brain. It seems to me likely that it is in part at least real, for the following 
reasons : first, the cerebral hemispheres have attained relatively enormous develop- 
ment late in their phylogenetic history ; and again from the functional standpoint 
the cerebrum is the most variable part of the brain. 
The correlations of the weight of the cerebrum with age and stature are both 
somewhat lower than the corresponding values for the other series of males falling 
within the ages 20 to 80. The ditfei-ences can hardly be considered as significant 
however in view of the probable errors. 
For the coefficient of regression of brain-weight on age I find bi = — l-06o, and 
on stature 6i = 2-178. By comparing these with the regression coefficients for the 
entire encephalon on the same characters in the series previously discussed it 
becomes evident at once to wh-at a great extent changes in the total brain-weight 
are due to changes in the weight of the cerebrum. Unfortunately it is not 
possible to get relative figures here on account of lack of knowledge of the 
regression of the total brain-weight on stature and age for the English series. 
Of course the weight of the cerebrum forms a large part (ca. 87 per cent, for the 
English series) of the total brain-weight. The problem here is to determine 
whether the changes in the weight of the cerebrum cause less or more than 
their proportional part (say 87 per cent.) of the changes in total brain-weight 
due to stature and age changes. I have tried a number of approximate methods 
10^2 
