Freiburger historische Bestände - digital

68

Cunningham Memoirs.

representative of the latter.* I have on a previous occasion j- endeavoured
to show that the sulcus transversus of Ecker cannot (in its entirety at least)
be regarded as equivalent to the " Affenspalte," and this being assumed,
the fact of the early disappearance of Bischoff's fissura perpendicularis
externa cannot be quoted as evidence against its being the transitory
representative in the human foetus of the " Affenspalte." Lately I have
obtained the brain of a newly-born male child (fig. 23) which shows a
condition bearing very closely upon this question. The sulcus transversus
of Ecker (s.t.) is present, but behind it there is another and larger transverse
sulcus, which communicates below with the former, and which I
am strongly inclined to believe represents a persistent condition of the
fissura perpendicularis externa, or, in other words, of the " Affenspalte."

Fig. 23.—Eight hemisphere of new-born child, n., fissure of Rolando ; p.c, post-central
sulcus; k.h., ramus horizontals of the intraparietal fissure; r.o., ramus
occipitalis; s.t. sulcus transversus occipitalis, of Ecker; a.s. "Affenspalte."

But in addition to all this it can be easily proved that the " Affenspalte
" in the ape is a complete fissure. If the inner wall and hippocampus
minor of the posterior horn of the lateral ventricle be carefully removed,
so as to exhibit the deep surface of the outer wall, a smooth vertical
elevation will be seen upon it which corresponds to the bottom of the
" Affenspalte " (PI. iv., fig. 2, e.).

* In a former paper upon the "Intraparietal Sulcus " (Journ. Anat. and Phys., Jan., 1890),
I expressed a different opinion, but I am now satisfied that in this I was wrong,
f Journ. Anat. and Phys., Jan., 1890.