504 L. BOLK 
cence of the occipital and mastoid bones on the contrary does 
not cause a striking deformation of the skull or the head. In 
some cases of a premature union of these two bones I met with a 
somewhat peculiar form of the occipital region of the skull. 
But this peculiarity can scarcely be observed during life because 
the greater part of this region of the skull is covered by the 
muscles of the neck. Now on the contrary, the deformity be- 
comes more visible when obliteration of the sagittal suture 
occurs in early life. The effect of this process is clearly visible 
and an extensive literature in all the principal languages has 
treated of this subject. We may distinguish two schools of 
method in this literature, the purely descriptive and the etio- 
logical. The investigations of the former simply reported the 
description of the scaphocephalic skulls, without referring to the 
origin of the deformity. 
The naturalists of the latter school did not limit their subject 
to a simple description, but they went more to the bottom 
of the problem and tried to point out the genetical cause of the 
deformity. The opinions of this group were directed in that 
way principally by a work of Virchow. In it the author dem- 
onstrates that the anatomical details characteristic of the 
scaphocephalic skull, were due to the coalescence of the two 
parietal bones in an early stage of development. Before Vir- 
chow this hypothesis had been defended by von Baer, but the 
correlation between cause and effect was clearly demonstrated 
for the first time by Virchow. 
However, though I intend to write about the genetical rela- 
tion between skull deformation and premature obliteration of 
sutures in a following paper, still I wish to lay stress here upon 
the justness of an observation already made by Huxley, and 
which was confirmed by my investigation. This famous natur- 
alist demonstrated infantile skulls, absolutely normal in shape 
and size, although the sagittal suture was entirely obliterated. 
One might observe that in such cases the individual died shortly 
after the synostosis of the suture and that the skull had there- 
fore no time to deform. To this supposition I will reply that 
the number of skulls with premature obliteration and without- 
