Robert Bennett Bean ~ 371 
and more readily visualized on the charts than would be the case with 
averages or curves. Horizontal lines are drawn on the charts to represent 
the means of the radii of the anterior association centers (ordinates), 
vertical lines are drawn to represent the means of the radii of the pos- 
terior association centers (abscisse), and lines are drawn at 45° from 
these to represent their combined means. In Chart I the Caucasian or- 
dinate mean is 69.5, the Negro ordinate mean is 65.5, 1. e., the Caucasian 
brains have a mean radius to the right anterior association center of 69.5 
mm., while the mean radius to this center in the Negro brains is only 
65 mm long. The Caucasian and Negro abscissa means are the same, 
72.5 mm., therefore the mean radius to the right posterior association 
center is the same in the two races. A comparison of the means of the 
two sides taken from Charts IT and II is found in the following table: 
TABLE IIc. 
MEANS OF THE ASSOCIATION CENTERS. 
Left Side. Right Side. 
Ca 2 = —_ 
Bo 68 #2 68 
2 Em Difference of the a8 Ha Difference of the 
oO Qs combined means. on ge combined means. 
ee oe i, iS 
<5 a << <5 <4 
Caucasian ... 69 (als 71.25 — 70 =.1.25 69.5 TS 72.5 — 70 =2.5 
ING2ZTOP cas sis es 65 zed 76.5 —70—6.50 65.5 UAE ih. ——10'==7,0 
The ordinate means are slightly larger on the right side than on the 
left side in the two races, hence the mean anterior association center is 
larger on the right than on the left. It is demonstrated (Table II*) that 
the averages of the anterior association centers are slightly larger on the 
right side than on the left in the females of the two races, but the relative 
difference is in favor of the left side in both male and female. This is evi- 
dent from the index of the association centers (Table II *) and from the 
differences of the combined means (Table II¢). The differences of the 
two sides are slight and may be negligible in the means and the averages. 
On the other hand the extremes (Table IL”) present a marked racial dif- 
ference in relation to the two sides of the brain, the left anterior associa- 
tion center being large in the Negro extremes and small in the Caucasian 
extremes. The conclusion is that the extremes affect both the means and 
the averages, explaining the apparent contradiction in each. The abscissa 
means are the same for all, except on the left side of the Caucasian which 
is 1 mm. less than the others. This indicates a smaller posterior associa- 
tion center on the left side of the Caucasian. The differences of the com- 
