M. G. Schlapp 273 
It is very likely that the phylogenetic secondary sight centers (cor- 
tex) of the dog and cat have not relieved the phylogenetic primary sight 
centers (Thalamus and corpora quadrigemina) of their functions (in 
the sense of Steiner) to such a degree as in the brain of the monkey 
and man; hence the lack of development of the cortex and lateral genic- 
ulate bodies in dog and cat. It is possible that Goltz was not entirely 
wrong when he said that after the destruction of the entire cortex of the 
dog he could still see to some extent. 
If this cortex, which presents such a characteristic structure in the 
monkey, and which is so sharply and so plainly differentiated from the 
adjoining parietal cortex, alone represents the visual cortex in the 
monkey, why should it not likewise alone represent the visual cortex in 
man? We may assume, with fair certainty, this to be the case. As the 
visual region can be sharply defined by its structure, its localization also 
ought to be definitely fixed. It has been demonstrated that the visual 
region nowhere passes over the margin of the longitudinal fissure onto 
the convex surface of the hemisphere, and that in the cases examined 
by myself, it assumes a pyramidal shape. The point of the pyramid 
lay in the anterior extremity of the calearine fissure, the base posteriorly 
at the margin of the longitudinal fissure. The upper side of the pyra- 
mid projected as far as above the middle of the cuneus, the lower side 
down to the gyrus fusiformis and partly into it. 
It is possible that the visual region varies in different brains. This 
variation may be due to the calcarine. fissure, the course and extent of 
which is variable in different brains. 
GENERAL. 
In conclusion, a few general remarks on the arrangement of the cells 
of the cerebral cortex seem desirable. é 
In the human cortex, the seven-layer structure seems to coincide, 
according to its situation, with the association centers of Flechsig. He 
Says: 
“The plainly evident differences in the structure of the cortex of the 
central gyri, the calearine fissure, the hippocampal gyrus, etc., have already 
been known for a long time, though strange to say they have not been 
sufficiently appreciated. On the other hand, it requires subtle research to 
demonstrate, for instance, differences between the cortex of the second 
frontal gyrus of the inferior parietal gyrus, of the second temporal gyrus, 
etc. If we measure the ganglion cells for their largest sizes, we obtain 
differences which can be expressed in figures, to be sure, but the type, 
as a rule, remains the same. We must, however, not overlook the fact that 
the border regions of sensory and association centers present occasionally 
