Freiburger historische Bestände - digital

224

Cunningham Memoirs.

either extremely feeble or entirely absent. The " Affenspalte," therefore,
is seen even on superficial inspection to lie well behind the parieto-occipital
fissure, whilst the whole length of the intraparietal sulcus is exposed on the
surface (fig. 46, p. 223). Further, the connexion of the intraparietal sulcus
and parieto-occipital fissure is very evident. In some cases this confluence
is perfectly free and unbroken; in other instances it is partially interrupted
by a low-lying feeble, deep annectant gyrus. In one hemisphere, which
I shall have to take special notice of later on, this deep gyrus has risen
to the surface,' and presents an appearance very similar to the condition
present in man (fig. 46, left hemisphere).

a.

. . Sylvian fissure.

9-

b.

. . Parallel sulcus.



e.

. . Intraparietal sulcus.

h.

d.

. . Fissure of Kolando.

i.

e.

. . Sulcus postcentrals superior.

k.

/■

. . Branch from intraparietal sulcus in front of
the first annectant gyrus.



Fig. 47.—Posterior part of the right cerebral hemisphere of the Chacma baboon looked at from above.

The occipital operculum has been removed.

. The upper end of the internal perpendicular

fissure.
. First annectant gyrus.
. . " Affenspalte."

. . Cut surface of the occipital operculum.

In carrying out our comparison between the intraparietal sulcus in man
and the corresponding sulcus in the apes, it is very evident, therefore, that
where an operculum exists in the latter, it is necessary, in the first instance,
to remove this structure, or at least to throw it well backwards.

The baboon will serve for our next stage (fig. 47). In the brain of this
form there is a deeply placed annectant gyrus (h.) (the first bridging convolution
) which partially cuts off the parieto-occipital fissure(g.) from the