1908.| Cell Lanunation of Cerebral Cortex of the Lemur. 505 
REFERENCES. 
1. Elliot Smith, ‘Catalogue of the Museum of the Royal College of Surgeons,’ Physio- 
logical Series, vol. 2. 
2. Campbell, ‘ Histological Studies on the Localisation of Cerebral Functions.’ 
3. Bolton, “The Exact Histological Localisation of the Visual Area of the Human 
Cerebral Cortex,” ‘Phil. Trans.,’ B, vol. 193, 1900. 
4. Brodmann, “ Beitriige zur histologischen Lokalisation der Grosshirnrinde,” Mitteilung 
M5, Bl: 
5. Ramon y Cajal, ‘Studien iiber die Hirnrinde des Menschen,’ part 4: “ Die Riechrinde 
beim Menschen und Saugetier,’ Leipzig, 1903. 
Addendum. 
_ All these drawings and sections were shown at the Physiological Society 
on January 25th, 1907; but we have delayed publication until the 
experiments performed by one of us, in conjunction with Professor 
Halliburton, had enabled us to map out the motor area. or we were 
uncertain of its extent in those regions where the giganto-pyramids are not 
found—namely, in the lower part of the motor area. Moreover, we found 
great difficulty in deciding upon the exact localisation of the visual area, for 
there is an undoubted difference in the structure of the cortex lying within 
the calcarine fissure and the circumjacent cortex on the mesial and external 
surface; which, although it shows by the fibre method a band which seems 
to be a definite line of Gennari, yet differs considerably in cell-structure 
from that within the calcarine fissure. The cortex within the fissure is less 
deep, and the pyramids and granules are more closely crowded together. 
This may quite probably be due to mechanical pressure within the fissure. 
But a more important difference is found in the fact that the solitary cells 
of Meynert lying within the fissure are more numerous, larger, and more 
typical in shape. In the surrounding region the cells, which are found in a 
corresponding position, form a more scattered line, are smaller, and are 
more pyramidal in shape. There is also a suggestion within the fissure of a 
pallid zone above the granules, and of a duplicated line of granules above this 
zone (vide fig. 10). This cannot be distinguished in the surrounding cortex. 
These observations find support in the fact that no movements were obtained 
by stimulation of the posterior pole. This experiment showed a marked 
contrast to the effects of stimulation of the pole in the ape. It may possibly 
be explained by the fact that the stimulus did not reach the solitary cells 
within the calcarine fissure. We have termed the cortex within the fissure 
“Visual A,” and the surrounding area “ Visual B.” While on the one hand 
the line of Gennari seems to stretch over the whole of the area we have 
mapped out as “visual,” on the other hand, for the reasons given above, we 
