LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 561 
In the left hemisphere, at the posterior extremity of the inferior occipital sulcus, 
there was a sinus, the entrance of the cautery which became visible superficially 
immediately external to the posterior extremity of the calcarine fissure, and then 
became lost to view. The under surface of the occipital lobe was somewhat blackened 
by the caustic. The course of the cautery remained concealed as far as the inner 
aspect of the uncus gyri hippocampi, where a small orifice was seen. Here the cautery 
emerged and grazed the optic tract, which was almost completely severed half way 
between the chiasma and the corpora geniculata. The crus cerebri was quite free 
from lesion. The right optic nerve was in sectional area only half the size of the left. 
In the right hemisphere there was an incision from the lower border of the inferior 
occipital convolution along the first or superior temporo-sphenoidal sulcus, and another 
at right angles to this, extending inwards to near the inner margin of the gyrus 
hippocampi. By these two incisions the greater portion of the middle and inferior 
temporo-sphenoidal convolutions with the hippocampal region were separated from the 
rest of the hemisphere, but remained in situ (fig. 173). 
The crura cerebri, corpora quadrigemina, corpora geniculata, and rest of the brain 
with the cranial nerves were uninjured. 
Sections of the brain, parallel to the fissure of Rolando (Plate 36, figs. 174-181), 
showed that in the left hemisphere the cautery had with the utmost precision pene¬ 
trated the centre of the cornu ammonis and broken it up from end to end without 
destroying the medullary fibres or cortex of the gyrus hippocampi. In many of the 
sections the cornu ammonis was merely a mass of blackened debris which fell out on 
handling. The left optic tract (figs. 178, 179, ISO) is seen to have been severed 
between the chiasma and the corpora geniculata. 
In the right hemisphere the sections show an extensive breaking up of the middle 
and inferior temporo-sphenoidal convolutions, and an almost complete severance of the 
medullary fibres of the hippocampal region, the destruction being most complete near 
the anterior extremity of the temporo-sphenoidal lobe, where only a small portion of 
the inner aspect of the tip of the gyrus hippocampi remained intact. The central 
ganglia and crura cerebri were uninjured throughout. 
Remarks. —In this case the lesion in the left hemisphere was limited with unusual 
precision to the cornu ammonis itself, which was thoroughly disorganised, without 
lesion of the medullary fibres or of the gyrus hippocampi. Tactile anaesthesia occurred 
on the opposite side of the body, both cutaneous and mucous, and the condition of 
the limbs was indicative of loss of the so-called muscular sense. The symptoms were, 
however, not of long duration, and already on the fourth day they were no longer 
discoverable. The right hemiopia proved, as had been diagnosed during life, to be 
due to lesion of the left optic tract. 
Apart from the right hemiopia, there was no other perceptible symptom beyond the 
loss of sensibility on the opposite side. 
The subsequent lesion of the right hemisphere, in which, along with the middle and 
mdccclxxxiv. 4 c 
