Freiburger historische Bestände - digital

Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 159

anterior perforated spot on the base of the brain. An almost continuous
rissural system, therefore, marks out the limits of the frontal portion
of the cerebrum.

14. The temporal pole is formed entirely by the forward growth of the
fore-part of the temporal operculum.

15. In the adult brain the insula is relatively longer in the male than
in the female. At all periods of growth it would seem that the insula is
relatively longer on the left side than on the right side. In the negro brain it
would appear that the insula is relatively shorter than in the European brain.

16. In the anthropoid ape the so-called anterior limb of the Sylvian
fissure is not homologous with either of the anterior limbs in man.

17. In the chimpanzee and orang there are only two opercula, viz.
the fronto-parietal and the temporal. The frontal and the orbital
opercula of the human brain are entirely absent in the anthropoid
cerebrum.

18. Restricting the term insula to that part of the hemisphere surface
which is concealed from view by opercula, the extent of this area in the ape
is very much less than in man. The central index is 18'2 in the chimpanzee
and 21*5 in the orang; in man the central index is 29'6. In the
lower apes the central index is higher than in the anthropoids.

19. In man the field of the insula shows marked changes with reference
to the cranial wall during intra-uterine life. More and more of its area
come to lie under cover of the parietal bone, and relatively less under cover
of the frontal bone, as development proceeds. In the adult the coronal line
cuts the insula in such a manner that 13 per cent, of its length lies in front
of it, and 87 per cent, behind it.

20. In the chimpanzee and the low apes no part of the insula lies in
front of the coronal line ; in the orang the upper and anterior corner of the
insula projects slightly in front of this line.

21. In the human infant and young child, as well as in the ape, the
point at which the stem of the Sylvian fissure reaches the outer surface of
the hemisphere is situated relatively further back than in the human adult.

22. The Sylvian fissure is relatively longer in the left hemisphere than
in the right, and in the ape than in man.