ON" THE FUNCTIONS OF THE CEREBRAL CORTEX. 
19 
lesion.* In one or two of these instances there has occurred softening of the 
occipital lobe, at least of its lower part, probably in consequence of derangement of 
its vascular supply. 
Conclusions and remarks. — Our experiments upon the occipital region, although 
few in number, seem to link together the conclusions arrived at by Munk, and by 
Ferrier and Yeo, as the result of their experiments. They indicate that both the 
occipital lobes and angular gyri are concerned with visual perceptions in such a 
manner that each occipital region is connected with the corresponding lateral half 
of each retina, and that a part only of the cortex of the region in question is able 
to take on in great measure, how completely cannot be determined in animals, the 
functions of the whole. This is in conformity also with the results of LuciANi. So 
far as the occipital lobe alone is concerned, our observations confirm the statement 
of Munk that the effect of this lesion is to produce a hemiopic disturbance of visual 
consciousness. But the imperfect vision which remains after removal of both occipital 
lobes (see Cases 25 and 26) suggests that the area which is concerned with visual 
consciousness is not confined to those lobes, as was inferred by Munk, but extends 
over into the angular gyrus, permanent hemiopia being produced by the subsequent 
removal of that convolution. It will, however, be necessary that further experiments 
should be undertaken in order to determine more precisely, not only the extent, but 
also the relative importance of the anterior, posterior, and mesial portions of the 
visual area of the cortex.t 
IV. — Results op Experiments upon the Temporo-sphenoidal Lobe and on 
THE Limbic Lobe. 
We have in several instances effected the removal of the greater part of the 
temporo-sphenoidal lobe. Our object in most of these experiments was to get at the 
hippocampal region in order to remove or destroy the hippocampus and uncinate g5^rus, 
a lesion which had only been performed hitherto by Ferrier, partly in conjunction 
with Yeo, and which in the hands of those observers was followed by hemiansesthesia 
* LuciANi (" On the Sensorial Localisations in the Cortex Cerebri," ' Brain,' vol. 7) appears disposed 
to regard these cases as being due to injury of an extension of the visual region into the temporal lobe. 
But, since the main centre for vision (in the occipital lobe) is intact, one would scarcely expect hemiopia 
to result from the removal of an outlying part ! 
f A further investigation upon this region and into the parts of the cortex which are connected with 
other special sense functions is, in fact, now being carried on by one of us, in the hope of succeeding 
in clearing up some of the discrepancies in the evidence of previous observers. We may perhaps here 
most conveniently notice a statement which has been made by Dr. Fereiee in the second edition of his 
•Functions of the Brain,' to the effect that we had removed tbe occipital lobes on one or both sides 
" without the slightest appreciable impairment of vision." It will be seen from the text, and from our 
Record of Cases, that this is a mistake. It appears to have arisen solely from a misunderstanding, for, 
whereas we informed Dr. Feeeier that we had not been able to determine that this lesion produced any 
'permanent impairment of vision, he understood, it would seem, that we had not obtained any effect 
whatever, 
D 2 
