Freiburger historische Bestände - digital

228

Cunningham Memoirs.

sulcus transversus occipitalis of Ecker. The whole arrangement is very
similar to what we have seen in the chimpanzee and the aberrant hemisphere
of Cehus albifrons. I have already referred to this cerebral hemisphere
(p. 68), so I need not enter into the condition it presents in further
detail. I may mention, however, that I have seen the same condition
present on one or two occasions in the adult human brain. I am therefore
very far from denying that the " Affenspalte " is invariably absent
in man. I only contend that it is not identical with the sulcus transversus
of Ecker.

Fig. 49.—Right hemisphere of new-born child. r., fissure of Rolando; p.c, postcentral sulcus;

e.h., ramus horizontalis of the intraparietal fissure; r.o., ramus occipitalis; s.t., sulcus
transversus occipitalis of Ecker ; a.s., "Affenspalte"; p.o., parieto-occipital fissure.

As we have noted, the occipital part of the intraparietal sulcus in the
human brain is either continuous with the main part of the fissure, or else
it has a separate origin in the superior parietal lobule. As it passes backwards
it sends a branch in front of the first annectant gyrus, and in its
typical condition divides in the occipital lobe beyond that gyrus into two
terminal branches. These are so widely spread out that they deviate from
each other very nearly in the same straight line, and constitute the sulcus
transversus. The lower limb of the bifurcation owes its origin undoubtedly
to the intraparietal sulcus ; it corresponds to the lower part of the short
descending limb in the apes which is brought into view when the operculum
is removed. The upper limb bounds the first annectant gyrus
posteriorly, and it is more difficult to decide upon its nature. In the
baboon the first annectant gyrus is bounded behind by the upper part of