406 Some Racial Peculiarities of the Negro Brain 
is slightly altered by shifting the axis up and down, the relations to dif- 
ferent points remain the same. Shifting the position of the brain center 
forwards or backwards indicates altered relations of the anterior or pos- 
terior extremities of the brain outlines and is something to be desired as 
an indication of existing conditions. The brain center, then, is a com- 
paratively constant point and is a good one to use as a basis for all meas- 
urements of the brain. By means of the brain axis and the brain center, 
racial and sexual differences are demonstrated in the size and shape of 
the corpus callosum; in the position of the fissure of Rolando; in the 
amount of brain substance anterior and posterior to this fissure; in the 
relations of the foramen of Munro to the whole brain, to the whole cor- 
pus callosum, to the genu and the splenium, and the relation of these 
parts to one another and to other parts of the brain; and by means of the » 
brain axis and the brain center a system of notation is devised whereby 
any point anywhere about the brain may be located definitely and accu- 
rately. This may be done by representing the brain as a sphere, and us- 
ing degrees of latitude and longitude, in this way bringing everything to 
the brain center as a basis. The degrees of longitude may be represented 
by semicircles connecting the extremitis of the brain axis and extending 
over the surface of the brain in the direction of its long diameter. De- 
grees of latitude may be represented by lines joining the terminal points 
of radii drawn from the brain center to these semicircles. The anterior 
end of the brain axis represents the north pole, and the posterior end the 
south pole. The equator is represented by the outline of a vertical plane 
passing through the vertex of the brain and through the brain center at 
right angles to the brain axis, supposing the brain to be in its normal po- 
sition with the body standing erect in all this description. The brain 
axis will be horizontal under such conditions. A horizontal plane passing 
through the axis and the right hemisphere will cut a semicircle around the 
side of this hemisphere and this semicircle represents 0° longitude, which 
will be called L. 0°. Revolve this plane to the left and upward through 
a distance of 360° to its original position, and as it traverses the circle 
its different positions in the course of its transit will vary from 0° to 
360°, any one of which may be located on the brain surface. Thus the 
mesial surface of each hemisphere above the axis will be L. 90°, the 
mesial surface below the axis will be L. 270°, the horizontal plane of the 
left hemisphere opposite L. 0° and similar to it will be L. 180°, and in- 
termediate planes likewise according to position. Jn like manner the planes 
of the outlines represented in Table IT will be L. 45° for the right hemi- 
sphere and L. 135° for the left. The degrees of latitude as radii from 
the brain center begin at the north pole and pass towards the vertex of 
