140 Drs. F. W. Mott and W. D. Halliburton. [Nov. 14, 
auditory centre, which analogy would teach us to place on the opposite side 
of the Sylvian fissure. This, however, did not obtain in all cases, and in one 
experiment the area passed upwards so as to slightly overlap the lateral 
fissure. 
As already noted in the protocols, repeated attempts to evoke eye move- 
ments from the occipital pole led to entirely negative results. It is quite 
certain that this region is, as in other animals, the visual area, for histo- 
logical examination of this part of the brain shows it to possess a well- 
marked line of Gennari, and the other structural features of the visual 
cortex. It is quite possible that if we had been able to stimulate in the 
depth of the calcarine fissure, where the solitary cells of Meynert are more 
abundant, we might have obtained eye movemeuts. 
The Histology of the Excitable Area. 
It is a comparatively easy matter to map out the area containing the 
large Betz cells; moreover, although, as in the primates, the region of cortex 
behind the motor area contains large pyramidal cells with Nissl granules, 
yet this can be differentiated from-the motor area proper by the existence of 
a granular layer, a sure sign of sensory function. Fig. 1, Plate 4, shows the 
type of cortex with the giant Betz cells; fig. 2, on the same plate, shows the 
type of cortex with the smaller Betz cells. The accompanying drawings in 
the text indicate the extent and boundaries cof these two types, the size 
of the Betz cells being roughly shown by the size of the dots. 
Diagrams A, B, and C are drawings of the outer and mesial surfaces of one hemisphere 
(A and C), and a drawing of the cerebrum as seen from above (B). The dotted area is 
the portion characterised by the possession of Betz cells, the size of which is roughly 
indicated by the size of the dots. 
The first type of cortex (with large Betz cells) covers that part of the 
outer and mesial surface which lies between the posterior end of the sulcus 
rectus, the anterior end of the sulcus lateralis, and the intercalary sulcus. 
It is continued further forward within the sulcus rectus than can be indicated 
