PROFESSORS D. FERRIER AND G. F. YEO ON THE EFFECTS OF 
53 4 
the right hemisphere of XVIII., showing the point at which the cautery entered the 
extremity of the occipital lobe, and the groove which it made immediately internal to 
the collateral fissure; and the frontal aspect of the same portion of the brain, show¬ 
ing the track of the cautery in the lower and inner temporo-sphenoidal region. Figs. 
97-102 are a series of frontal sections of the hemisphere from the occipital to the 
anterior portion of the temporo-sphenoidal region. In figs. 97 and 98 the walls of the 
calcarine fissure are seen to be completely broken up. Figs. 99 and 100 show total 
disorganisation of the medullary fibres of the lower temporo-sphenoidal region and 
complete disappearance of the cornu ammonis. The gyrus hippocampi is l’epresented 
by only a thin shell of cortex possessing no medullary connexions. 
Figs. 101 and 102 were stained with logwood, and therefore do not show so well as 
prints. In these sections there are still remnants of the hippocampus, and some of the 
medullary fibres of the superior temporo-sphenoidal convolution are involved in the 
lesion. But with the exception of some lesion of the base of the lenticular nucleus, 
seen in fig. 102, the area of destruction was entirely clear of the central ganglia and 
internal capsule. The crus cerebri was absolutely uninjured. 
It will thus be seen that there are no grounds for attributing the tactile ansesthesia 
observed in these two experiments to destructive lesion of any other part of the 
hemisphere than the cortex and medullary fibres of the hippocampal and lower 
temporo-sphenoidal region. The profoundness of the ansesthesia exhibited in these two 
cases was indicated by the almost total absence of any sign of sensation to thermal 
stimulation of the severest form on the side opposite the lesion. 
Tn Experiment XVII., in which the track of the cautery swerved away from the 
hippocampus, anaesthesia was not observed until by the secondary softening the 
hippocampal region, as shown in the sections, became involved. In this it was noted 
that there were some indications of basilar meningitis, but there was no softening or 
destructive lesion of any part of the brain except that of the hippocampal and lower 
temporo-sphenoidal region described and figured. 
These experiments were made without antiseptic precautions, and therefore the 
exact limitation of the primary lesions could not be ensured, owing to secondary 
inflammation which invariably set in. And this is a fact which must always be 
reckoned with in estimating the effects of cerebral lesions made without antiseptics. 
It is altogether impossible to reach and destroy the hippocampal region without 
causing injury to some other parts of the brain, and it is necessary to eliminate the 
effects attributable to these by previous experiments. 
In the experiments about to be related the hippocampal region was injured or 
destroyed as in former experiments by heated wires or other cauteries, pushed through 
the occipital lobe downwards and forwards along the hippocampal region, or guided 
along this region by a director inserted between the under surface of the occipital 
lobe and the tentorium cerebelli ; or by means of incisions from the convex aspect of 
the temporo-sphenoidal lobe so calculated as to direction and depth as to sever the 
