536 
PROFESSORS D. FERRIER AND G. F. YEO OX THE EFFECTS OF 
On the eighth day the difference, if any, was very doubtful, and examination at 
various times subsequently did not indicate any perceptible difference as to the signs 
of sensation on the right and left side to various forms of tactile stimuli. The 
animal, which continued hemiplegic on the left side, was killed with chloroform 
considerably over a year after the above-mentioned operation. 
Post-mortem examination .-—The condition of the right hemisphere has been already 
described and figured. 
In the left hemisphere an orifice, slightly torn, existed at the posterior extremity of 
the occipital lobe, indicating the point of entrance of the cautery. This led into a 
shallow groove passing along the upper two-thirds of the gyrus hippocampi (lingual 
lobule), exactly confined between the calcarine and collateral fissures, and ending at a 
point one centimetre posterior to the uncus, where the cautery. appeared to have 
entered and buried itself (fig. 103). 
The grey matter of the posterior three-fourths of the gyrus hippocampi appeared to 
have been peeled or shelled off, exposing the medullary fibres and outline of the cornu 
ammonis. The cortex of the anterior extremity of the gyrus hippocampi and uncus 
was uninjured superficially. 
The base of the brain otherwise-the crura cerebri, optic tracts, and cranial nerves 
—was intact. 
A series of sections, cut obliquely downwards and forwards parallel to the fissure 
of Rolando, of which sun-prints are given in figs. 104-109, showed that the cortex of 
the gyrus hippocampi had been for the most part sheared off down to the medullary 
fibres of the cornu ammonis. 
This was exposed, but not separated from its medullary connexions, so that it pro¬ 
jected in the sections like a crozier. Towards the lower or anterior portion of the 
gyrus there still remained a portion of the cortex, adjoining the collateral fissure, 
while that immediately supporting the hippocampus was removed (figs. 106-108). 
In the sections which cut the anterior third of this region it was seen that 
the cautery had penetrated the anterior portion of the hippocampus and nucleus 
amygdalae, causing a hole in this region, as seen in tranverse section (fig. 109). The 
convex aspect of the gyrus hippocampi was at this point intact. 
Remarks .—This experiment shows that destructive lesion implicating the cortex of 
the gyrus hippocampi, and perhaps to some extent the medullary fibres of the hippo¬ 
campus or cornu ammonis, causes some degree of impairment of tactile sensibility, at 
first well marked, but becoming less distinct, and not perceptible to ordinary tests a 
week after the operation. 
The case was instructive in the comparison (for which the double experiment was 
devised) which it allowed between the effects of lesion of the motor region and of the 
hippocampal region. Though the left limbs were greatly impaired as to motor power, 
no defect could be discovered in their sensibility throughout; while the right limbs 
