108 
In the further development there should originate out of this part 
lying at the back, out of its upper portion, an outgrowth, directed 
frontalwards, which grows towards the back ridge of the upper 
parietal-convolution. This frontalwards growing piece will come in 
contact with a part of the upper parietal convolution, which is 
growing backwards, therefore towards the occipital pole. When a 
union is accomplished by these two parts which are growing towards 
each other and which belong respectively to the lobus parietalis and 
occipitalis, then the 1st pli de passage is formed. 
As the above said shows the way in which ZvekKeRKANDL thinks 
the origin of the 1s* pli de passage to be, yet on the other hand 
he joins the other investigators, who are of opinion that the 1st and 
24 Jateral pli de passage are lying primarily in de depth and only 
secondarily come to the surface. Thus be writes on page 289, on 
which he divides the Ist pli de passage into three forms: “Bei der 
“dritten Form ist die | Uebergangswindung wie bei den Anthro- 
“poiden an die Oberfläche der convexen Hemisphärenfläche ge- 
treten”. 
From this it is distinctly proved that he assumes that these plis 
de passage ought to be lying in the depth, but in a few cases can 
come to the surface. 
It is to the merit of Konrsrveer, who first distinctly announced 
the probability, that the conception prevailing up to the present 
day was wrong. 
On p. 242 he writes: “Ich nehme an, dass die Uebergangswin- 
dung bei allen Affenembryonen erst oberflächlich liegt, etwa wie 
die Insula Reilii (ber Embryonen) und erst später durch Entwicklung 
der angrenzenden Teile in die Tiefe versenkt wird”. 
His communication did not receive the attention which it 
deserved. 
The cause of this has to be looked for in different directions. 
In first instance, the view of the plis de passage which primarily 
are lying on the surface, is totally in contradiction with what was 
accepted till now. The hypothesis of ZvCRERKANDIL, which I previ- 
ously described in short, and which appeared in the same year as 
the communication of KOHLBRUGGE, points to it. 
As the latter moreover only possessed full-termed material, he 
could not deliver the evidence to his conception. 
These two facts in themselves made already improbable that much 
attention should be drawn to his communication. 
Add to it moreover, that he does not always consistently work 
out his view, as he e.g. writes on page 220: “CunnincHam hat die 
