Freiburger historische Bestände - digital

240

Cunningham Memoirs.

with the straight line which passed through the hinder pin-head (the
" intraparietal angle "), was produced on the varnished sheet of glass, and
could be easily measured. The following are the results which were
obtained by this method:—

Intraparietal Angle.



Male.

Female.



Number
of Hemispheres
.

Average
Angle.

Number
of Hemispheres
.

Average
Angle.

Adult human brain, ......

Foetal brains (from eighth month to full-time),

23
11

20°-3
l7°-2

11

16

l7°-9
13°-4

It will be apparent that the greater this angle is, the greater must be
the obliquity of the sagittal part of the intraparietal sulcus. Such being
the case, it is interesting to observe that it is not the female (as Eudinger
has said) which has the most oblique fissure, but the male, and this is seen
both in the foetus and the adult. Further, it is important to note that the
foetal brain exhibits less obliquity in the direction of the sagittal part of the
intraparietal sulcus than the adult.

As for the anthropoid brains I found only one chimpanzee hemisphere
in which the hinder end of the sulcus was nearer to the mesial
border than the anterior end. The intraparietal angle in this specimen
was 20° (fig. 36, p. 204, right hemisphere). In four orang hemispheres,
and in one chimpanzee hemisphere, the sulcus ran parallel to the mesial
border, whilst in two chimpanzee hemispheres the hinder end of the sulcus
was further distant from the mesial border than the anterior end. If,
therefore, in the brains of the distinguished men referred to by Eudinger
the direction of the sagittal part of the intraparietal sulcus is such as he
describes, it must be regarded not as high character but as an approximation
to the anthropoid and infantile types.